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OpenGL OpenGLBook.com sample - I'm not getting it to work!

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Hello fellows!

So, i've been updating my OpenGL knowledge and managed to get stuck. I've followed the guides over at OpenGLBook.com and all was going well, untill i hit Chapter 4.
The code i've written is next to identical to their sample code, yet their code works and mine doesn't. I have even copy pasted my code into theirs, replacing every function with mine, and that still works. But my code alone is not up to the task sadly. There must be something i'm missing. Please, help me out!

My code


/*
* Free Glut test.
*/
#include "utils.h"

/* === DEFINITIONS === */
#define WINDOW_TITLE "Chapter 4: 3D"
#define SHADER_PROGRAM 0
#define SHADER_FRAGMENT 1
#define SHADER_VERTEX 2
#define BUFFER_VAO 0
#define BUFFER_VBO 1
#define BUFFER_IBO 2

/* === GLOBAL VARIABLES === */
GLuint projMatUniLoc, viewMatUniLoc, modelMatUniLoc;
GLuint bufferIds[3] = {0}, shaderIds[3] = {0};
int windowWidth, windowHeight, windowHandle;
float cubeRotation;
clock_t lastTime;
unsigned frames;

/* === MATRIXES === */
Matrix projectionMatrix, viewMatrix, modelMatrix;

/* === FUNCTION PROTOTYPES === */
void init(int, char **);
void initWindow(int, char **);
void resize(int, int);
void render(void);
void timer(int);
void idle(void);
void createCube(void);
void destroyCube(void);
void drawCube(void);

/*
* main():
* Main entry point of the application.
*/
int main(int argc, char **argv) {
/* Initialize everything we need */
init(argc, argv);

/* Start the glut loop */
glutMainLoop();

exit(EXIT_SUCCESS);
}

/*
* init(argc, argv):
* Initializes everything we need to start running.
*/
void init(int argc, char **argv) {
GLenum ret;
/* Create our openGL window */
windowWidth = 1024;
windowHeight = 768;
initWindow(argc, argv);

/* Initialize glew */
ret = glewInit();
if (GLEW_OK != ret) {
fprintf(stderr, "ERROR: %s\n", glewGetErrorString(ret));
exit(EXIT_FAILURE);
}

/* Get the running openGL version */
fprintf(stdout, "INFO: OpenGL Version: %s\n", glGetString(GL_VERSION));

/* Empty potential errors */
glGetError();

/* Clear the screen */
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

/* Enable depth test */
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LESS);
ExitOnGLError("ERROR: Could not set OpenGL depth testing");

/* Enable culling of faces */
glEnable(GL_CULL_FACE);
glCullFace(GL_BACK);
glFrontFace(GL_CCW);
ExitOnGLError("Error: Could not set OpenGL culling");

/* Setup out default matrices */
modelMatrix = IDENTITY_MATRIX;
projectionMatrix = IDENTITY_MATRIX;
viewMatrix = IDENTITY_MATRIX;
TranslateMatrix(&viewMatrix, 0, 0, -2);

/* Create our initial cube */
createCube();
}

/*
* initWindow(argc, argv):
* Create the openGL window for us.
*/
void initWindow(int argc, char **argv) {
/* Initialize glut */
glutInit(&argc, argv);
glutInitContextVersion(4, 0);
glutInitContextFlags(GLUT_FORWARD_COMPATIBLE);
glutInitContextProfile(GLUT_CORE_PROFILE);
glutSetOption(GLUT_ACTION_ON_WINDOW_CLOSE, GLUT_ACTION_GLUTMAINLOOP_RETURNS);
glutInitWindowSize(windowWidth, windowHeight);
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);

/* Create the window */
windowHandle = glutCreateWindow(WINDOW_TITLE);
if (windowHandle < 1) {
fprintf(stderr, "ERROR: Could not create window.\n");
exit(EXIT_FAILURE);
}

/* Set glut callback functions */
glutReshapeFunc(resize);
glutDisplayFunc(render);
glutIdleFunc(idle);
glutTimerFunc(0, timer, 0);
glutCloseFunc(destroyCube);
}

/*
* rezie(width, height):
* Resize the openGL window.
*/
void resize(int width, int height) {
/* Save dimensions */
windowWidth = width;
windowHeight = height;

/* Set viewport */
glViewport(0, 0, width, height);

/* Change our projection matrix */
projectionMatrix = CreateProjectionMatrix(60,
(float)windowWidth / windowHeight, 1.0f, 100.0f);
glUseProgram(shaderIds[0]);
glUniformMatrix4fv(projMatUniLoc, 1, GL_FALSE, projectionMatrix.m);
glUseProgram(0);
}

/*
* render()
* Render our openGL scene.
*/
void render(void) {
++frames;

/* Clear screen */
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

/* Draw our cube */
drawCube();

/* Swap buffers and update display */
glutSwapBuffers();
glutPostRedisplay();
}

/*
* idle():
* Logic function.
*/
void idle(void) {
glutPostRedisplay();
}

/*
* timer(val):
* Timer to count FPS.
*/
void timer(int val) {
char fpsString[512];

if (val != 0) {
/* Allocate memory and copy string */
sprintf(fpsString, "%s: %d FPS @ %d x %d", WINDOW_TITLE,
frames * 4, windowWidth, windowHeight);

/* Set it as title */
glutSetWindowTitle(fpsString);
}

frames = 0;
glutTimerFunc(250, timer, 1);
}

/*
* createCube():
* Setup the cube.
*/
void createCube(void) {
const Vertex vertices[8] = {
{{-0.5f, -0.5f, 0.5f, 1}, {0, 0, 1, 1}},
{{-0.5f, 0.5f, 0.5f, 1}, {1, 0, 0, 1}},
{{0.5f, 0.5f, 0.5f, 1}, {0, 1, 0, 1}},
{{0.5f, -0.5f, 0.5f, 1}, {1, 1, 0, 1}},
{{-0.5f, -0.5f, -0.5f, 1}, {1, 1, 1, 1}},
{{-0.5f, 0.5f, -0.5f, 1}, {1, 0, 0, 1}},
{{0.5f, 0.5f, -0.5f, 1}, {1, 0, 1, 1}},
{{0.5f, -0.5f, -0.5f, 1}, {0, 0, 1, 1}}
};
const GLuint indices[36] = {
0, 2, 1, 0, 3, 2, 4, 3, 0, 4, 7, 3,
4, 1, 5, 4, 0, 1, 3, 6, 2, 3, 7, 6,
1, 6, 5, 1, 2, 6, 7, 5, 6, 7, 4, 5
};

/* Generate the shader program */
shaderIds[SHADER_PROGRAM] = glCreateProgram();
ExitOnGLError("ERROR: Could not create shader program");

/* Load and attach shaders */
shaderIds[SHADER_FRAGMENT] = LoadShader("fragment.glsl", GL_FRAGMENT_SHADER);
shaderIds[SHADER_VERTEX] = LoadShader("vertex.glsl", GL_VERTEX_SHADER);
glAttachShader(shaderIds[SHADER_PROGRAM], shaderIds[SHADER_FRAGMENT]);
glAttachShader(shaderIds[SHADER_PROGRAM], shaderIds[SHADER_VERTEX]);

/* Link shader program */
glLinkProgram(shaderIds[SHADER_PROGRAM]);
ExitOnGLError("ERROR: Could not link shader program");

/* Retrive shader uniforms */
modelMatUniLoc = glGetUniformLocation(shaderIds[SHADER_PROGRAM], "modelMatrix");
viewMatUniLoc = glGetUniformLocation(shaderIds[SHADER_PROGRAM], "viewMatrix");
projMatUniLoc = glGetUniformLocation(shaderIds[SHADER_PROGRAM], "projectionMatrix");
ExitOnGLError("ERROR: Could not get shader uniform locations");

/* Generate and bind our vertex array object */
glGenVertexArrays(1, &bufferIds[BUFFER_VAO]);
ExitOnGLError("ERROR: Could not generate VAO");
glBindVertexArray(bufferIds[BUFFER_VAO]);
ExitOnGLError("ERROR: Could not bind VAO");
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
ExitOnGLError("ERROR: Could not enable vertex attributes");

/* Bind VBO and send data */
glGenBuffers(2, &bufferIds[BUFFER_VBO]);
glBindBuffer(GL_ARRAY_BUFFER, bufferIds[BUFFER_VBO]);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
ExitOnGLError("ERROR: Could not bind VBO to VAO");

/* Set the attributes for our VAO */
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, sizeof(vertices[0]), (GLvoid *)0);
glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, sizeof(vertices[0]),
(GLvoid *)sizeof(vertices[0].Position));
ExitOnGLError("ERROR: Could not set VAO attributes");

/* Bind IBO and send data */
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, bufferIds[BUFFER_IBO]);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
ExitOnGLError("ERROR: Could not bind IBO to VAO");
glBindVertexArray(0);
}

/*
* destroyCube():
* Destroy out little cubie.
*/
void destroyCube(void) {
/* Detach and delete shaders */
glDetachShader(shaderIds[SHADER_PROGRAM], shaderIds[SHADER_FRAGMENT]);
glDetachShader(shaderIds[SHADER_PROGRAM], shaderIds[SHADER_VERTEX]);
glDeleteShader(shaderIds[SHADER_FRAGMENT]);
glDeleteShader(shaderIds[SHADER_VERTEX]);
glDeleteProgram(shaderIds[SHADER_PROGRAM]);
ExitOnGLError("ERROR: Could not destroy shaders");

/* Delete and destroy buffers */
glDeleteBuffers(2, &bufferIds[BUFFER_VBO]);
glDeleteVertexArrays(1, &bufferIds[BUFFER_VAO]);
ExitOnGLError("ERROR: Could not destroy buffer objects");
}

/*
* drawCube():
* Draw the cube.
*/
void drawCube(void) {
float cubeAngle;
clock_t now;

/* Current time */
now = clock();
if (lastTime == 0)
lastTime = now;

/* Adjust rotation */
cubeRotation += 45.0f * ((float)(now - lastTime) / CLOCKS_PER_SEC);
cubeAngle = DegreesToRadians(cubeRotation);
lastTime = now;

/* Rotate the matrix */
modelMatrix = IDENTITY_MATRIX;
RotateAboutY(&modelMatrix, cubeAngle);
RotateAboutX(&modelMatrix, cubeAngle);

/* Use the shader program so we can manipluate */
glUseProgram(shaderIds[SHADER_PROGRAM]);

/* Adjust matrix uniform locations */
glUniformMatrix4fv(modelMatUniLoc, 1, GL_FALSE, modelMatrix.m);
glUniformMatrix4fv(viewMatUniLoc, 1, GL_FALSE, viewMatrix.m);
ExitOnGLError("ERROR: Could not set the shader uniforms");

/* Bind and draw the VAO */
glBindVertexArray(bufferIds[BUFFER_VAO]);
ExitOnGLError("ERROR: Could not bind VAO for drawing");
glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, (GLvoid *)0);
ExitOnGLError("ERROR: Could not draw the cube");

/* Done manipulating */
glBindVertexArray(0);
glUseProgram(0);
}




Their code


/* Copyright (C) 2011 by Eddy Luten

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

#include "Utils.h"
#define WINDOW_TITLE_PREFIX "Chapter 4"

int CurrentWidth = 800,
CurrentHeight = 600,
WindowHandle = 0;

unsigned FrameCount = 0;

GLuint
ProjectionMatrixUniformLocation,
ViewMatrixUniformLocation,
ModelMatrixUniformLocation,
BufferIds[3] = { 0 },
ShaderIds[3] = { 0 };

Matrix
ProjectionMatrix,
ViewMatrix,
ModelMatrix;

float CubeRotation = 0;
clock_t LastTime = 0;

void Initialize(int, char*[]);
void InitWindow(int, char*[]);
void ResizeFunction(int, int);
void RenderFunction(void);
void TimerFunction(int);
void IdleFunction(void);
void CreateCube(void);
void DestroyCube(void);
void DrawCube(void);

int main(int argc, char* argv[])
{
Initialize(argc, argv);

glutMainLoop();

exit(EXIT_SUCCESS);
}

void Initialize(int argc, char* argv[])
{
GLenum GlewInitResult;

InitWindow(argc, argv);

glewExperimental = GL_TRUE;
GlewInitResult = glewInit();

if (GLEW_OK != GlewInitResult) {
fprintf(
stderr,
"ERROR: %s\n",
glewGetErrorString(GlewInitResult)
);
exit(EXIT_FAILURE);
}

fprintf(
stdout,
"INFO: OpenGL Version: %s\n",
glGetString(GL_VERSION)
);

glGetError();
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LESS);
ExitOnGLError("ERROR: Could not set OpenGL depth testing options");

glEnable(GL_CULL_FACE);
glCullFace(GL_BACK);
glFrontFace(GL_CCW);
ExitOnGLError("ERROR: Could not set OpenGL culling options");

ModelMatrix = IDENTITY_MATRIX;
ProjectionMatrix = IDENTITY_MATRIX;
ViewMatrix = IDENTITY_MATRIX;
TranslateMatrix(&ViewMatrix, 0, 0, -2);

CreateCube();
}

void InitWindow(int argc, char* argv[])
{
glutInit(&argc, argv);

glutInitContextVersion(4, 0);
glutInitContextFlags(GLUT_FORWARD_COMPATIBLE);
glutInitContextProfile(GLUT_CORE_PROFILE);

glutSetOption(
GLUT_ACTION_ON_WINDOW_CLOSE,
GLUT_ACTION_GLUTMAINLOOP_RETURNS
);

glutInitWindowSize(CurrentWidth, CurrentHeight);

glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);

WindowHandle = glutCreateWindow(WINDOW_TITLE_PREFIX);

if(WindowHandle < 1) {
fprintf(
stderr,
"ERROR: Could not create a new rendering window.\n"
);
exit(EXIT_FAILURE);
}

glutReshapeFunc(ResizeFunction);
glutDisplayFunc(RenderFunction);
glutIdleFunc(IdleFunction);
glutTimerFunc(0, TimerFunction, 0);
glutCloseFunc(DestroyCube);
}

void ResizeFunction(int Width, int Height)
{
CurrentWidth = Width;
CurrentHeight = Height;
glViewport(0, 0, CurrentWidth, CurrentHeight);
ProjectionMatrix =
CreateProjectionMatrix(
60,
(float)CurrentWidth / CurrentHeight,
1.0f,
100.0f
);

glUseProgram(ShaderIds[0]);
glUniformMatrix4fv(ProjectionMatrixUniformLocation, 1, GL_FALSE, ProjectionMatrix.m);
glUseProgram(0);
}

void RenderFunction(void)
{
++FrameCount;

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

DrawCube();

glutSwapBuffers();
glutPostRedisplay();
}

void IdleFunction(void)
{
glutPostRedisplay();
}

void TimerFunction(int Value)
{
if (0 != Value) {
char* TempString = (char*)
malloc(512 + strlen(WINDOW_TITLE_PREFIX));

sprintf(
TempString,
"%s: %d Frames Per Second @ %d x %d",
WINDOW_TITLE_PREFIX,
FrameCount * 4,
CurrentWidth,
CurrentHeight
);

glutSetWindowTitle(TempString);
free(TempString);
}

FrameCount = 0;
glutTimerFunc(250, TimerFunction, 1);
}

void CreateCube()
{
const Vertex VERTICES[8] =
{
{ { -.5f, -.5f, .5f, 1 }, { 0, 0, 1, 1 } },
{ { -.5f, .5f, .5f, 1 }, { 1, 0, 0, 1 } },
{ { .5f, .5f, .5f, 1 }, { 0, 1, 0, 1 } },
{ { .5f, -.5f, .5f, 1 }, { 1, 1, 0, 1 } },
{ { -.5f, -.5f, -.5f, 1 }, { 1, 1, 1, 1 } },
{ { -.5f, .5f, -.5f, 1 }, { 1, 0, 0, 1 } },
{ { .5f, .5f, -.5f, 1 }, { 1, 0, 1, 1 } },
{ { .5f, -.5f, -.5f, 1 }, { 0, 0, 1, 1 } }
};

const GLuint INDICES[36] =
{
0,2,1, 0,3,2,
4,3,0, 4,7,3,
4,1,5, 4,0,1,
3,6,2, 3,7,6,
1,6,5, 1,2,6,
7,5,6, 7,4,5
};

ShaderIds[0] = glCreateProgram();
ExitOnGLError("ERROR: Could not create the shader program");
{
ShaderIds[1] = LoadShader("SimpleShader.fragment.glsl", GL_FRAGMENT_SHADER);
ShaderIds[2] = LoadShader("SimpleShader.vertex.glsl", GL_VERTEX_SHADER);
glAttachShader(ShaderIds[0], ShaderIds[1]);
glAttachShader(ShaderIds[0], ShaderIds[2]);
}
glLinkProgram(ShaderIds[0]);
ExitOnGLError("ERROR: Could not link the shader program");

ModelMatrixUniformLocation = glGetUniformLocation(ShaderIds[0], "ModelMatrix");
ViewMatrixUniformLocation = glGetUniformLocation(ShaderIds[0], "ViewMatrix");
ProjectionMatrixUniformLocation = glGetUniformLocation(ShaderIds[0], "ProjectionMatrix");
ExitOnGLError("ERROR: Could not get shader uniform locations");

glGenVertexArrays(1, &BufferIds[0]);
ExitOnGLError("ERROR: Could not generate the VAO");
glBindVertexArray(BufferIds[0]);
ExitOnGLError("ERROR: Could not bind the VAO");

glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
ExitOnGLError("ERROR: Could not enable vertex attributes");

glGenBuffers(2, &BufferIds[1]);
ExitOnGLError("ERROR: Could not generate the buffer objects");

glBindBuffer(GL_ARRAY_BUFFER, BufferIds[1]);
glBufferData(GL_ARRAY_BUFFER, sizeof(VERTICES), VERTICES, GL_STATIC_DRAW);
ExitOnGLError("ERROR: Could not bind the VBO to the VAO");

glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, sizeof(VERTICES[0]), (GLvoid*)0);
glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, sizeof(VERTICES[0]), (GLvoid*)sizeof(VERTICES[0].Position));
ExitOnGLError("ERROR: Could not set VAO attributes");

glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, BufferIds[2]);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(INDICES), INDICES, GL_STATIC_DRAW);
ExitOnGLError("ERROR: Could not bind the IBO to the VAO");

glBindVertexArray(0);
}

void DestroyCube()
{
glDetachShader(ShaderIds[0], ShaderIds[1]);
glDetachShader(ShaderIds[0], ShaderIds[2]);
glDeleteShader(ShaderIds[1]);
glDeleteShader(ShaderIds[2]);
glDeleteProgram(ShaderIds[0]);
ExitOnGLError("ERROR: Could not destroy the shaders");

glDeleteBuffers(2, &BufferIds[1]);
glDeleteVertexArrays(1, &BufferIds[0]);
ExitOnGLError("ERROR: Could not destroy the buffer objects");
}

void DrawCube(void)
{
float CubeAngle;
clock_t Now = clock();

if (LastTime == 0)
LastTime = Now;

CubeRotation += 45.0f * ((float)(Now - LastTime) / CLOCKS_PER_SEC);
CubeAngle = DegreesToRadians(CubeRotation);
LastTime = Now;

ModelMatrix = IDENTITY_MATRIX;
RotateAboutY(&ModelMatrix, CubeAngle);
RotateAboutX(&ModelMatrix, CubeAngle);

glUseProgram(ShaderIds[0]);
ExitOnGLError("ERROR: Could not use the shader program");

glUniformMatrix4fv(ModelMatrixUniformLocation, 1, GL_FALSE, ModelMatrix.m);
glUniformMatrix4fv(ViewMatrixUniformLocation, 1, GL_FALSE, ViewMatrix.m);
ExitOnGLError("ERROR: Could not set the shader uniforms");

glBindVertexArray(BufferIds[0]);
ExitOnGLError("ERROR: Could not bind the VAO for drawing purposes");

glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, (GLvoid*)0);
ExitOnGLError("ERROR: Could not draw the cube");

glBindVertexArray(0);
glUseProgram(0);
}

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What is happening? What "won't work"? Compile error? Crash? Black Screen? Any debug info?

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Hi Zomgbie,

What exactly doesn't work? You could provide some more specific information besides simply pasting the code from the samples:

Do you get any errors, black screens, can you tell me anything about the output? What platform are you on? What hardware are you using? Are you checking glGetError along the way?



The more info you can provide, the better.


Eddy


Hello fellows!

So, i've been updating my OpenGL knowledge and managed to get stuck. I've followed the guides over at OpenGLBook.com and all was going well, untill i hit Chapter 4.
The code i've written is next to identical to their sample code, yet their code works and mine doesn't. I have even copy pasted my code into theirs, replacing every function with mine, and that still works. But my code alone is not up to the task sadly. There must be something i'm missing. Please, help me out!

My code


/*
* Free Glut test.
*/
#include "utils.h"

/* === DEFINITIONS === */
#define WINDOW_TITLE "Chapter 4: 3D"
#define SHADER_PROGRAM 0
#define SHADER_FRAGMENT 1
#define SHADER_VERTEX 2
#define BUFFER_VAO 0
#define BUFFER_VBO 1
#define BUFFER_IBO 2

/* === GLOBAL VARIABLES === */
GLuint projMatUniLoc, viewMatUniLoc, modelMatUniLoc;
GLuint bufferIds[3] = {0}, shaderIds[3] = {0};
int windowWidth, windowHeight, windowHandle;
float cubeRotation;
clock_t lastTime;
unsigned frames;

/* === MATRIXES === */
Matrix projectionMatrix, viewMatrix, modelMatrix;

/* === FUNCTION PROTOTYPES === */
void init(int, char **);
void initWindow(int, char **);
void resize(int, int);
void render(void);
void timer(int);
void idle(void);
void createCube(void);
void destroyCube(void);
void drawCube(void);

/*
* main():
* Main entry point of the application.
*/
int main(int argc, char **argv) {
/* Initialize everything we need */
init(argc, argv);

/* Start the glut loop */
glutMainLoop();

exit(EXIT_SUCCESS);
}

/*
* init(argc, argv):
* Initializes everything we need to start running.
*/
void init(int argc, char **argv) {
GLenum ret;
/* Create our openGL window */
windowWidth = 1024;
windowHeight = 768;
initWindow(argc, argv);

/* Initialize glew */
ret = glewInit();
if (GLEW_OK != ret) {
fprintf(stderr, "ERROR: %s\n", glewGetErrorString(ret));
exit(EXIT_FAILURE);
}

/* Get the running openGL version */
fprintf(stdout, "INFO: OpenGL Version: %s\n", glGetString(GL_VERSION));

/* Empty potential errors */
glGetError();

/* Clear the screen */
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

/* Enable depth test */
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LESS);
ExitOnGLError("ERROR: Could not set OpenGL depth testing");

/* Enable culling of faces */
glEnable(GL_CULL_FACE);
glCullFace(GL_BACK);
glFrontFace(GL_CCW);
ExitOnGLError("Error: Could not set OpenGL culling");

/* Setup out default matrices */
modelMatrix = IDENTITY_MATRIX;
projectionMatrix = IDENTITY_MATRIX;
viewMatrix = IDENTITY_MATRIX;
TranslateMatrix(&viewMatrix, 0, 0, -2);

/* Create our initial cube */
createCube();
}

/*
* initWindow(argc, argv):
* Create the openGL window for us.
*/
void initWindow(int argc, char **argv) {
/* Initialize glut */
glutInit(&argc, argv);
glutInitContextVersion(4, 0);
glutInitContextFlags(GLUT_FORWARD_COMPATIBLE);
glutInitContextProfile(GLUT_CORE_PROFILE);
glutSetOption(GLUT_ACTION_ON_WINDOW_CLOSE, GLUT_ACTION_GLUTMAINLOOP_RETURNS);
glutInitWindowSize(windowWidth, windowHeight);
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);

/* Create the window */
windowHandle = glutCreateWindow(WINDOW_TITLE);
if (windowHandle < 1) {
fprintf(stderr, "ERROR: Could not create window.\n");
exit(EXIT_FAILURE);
}

/* Set glut callback functions */
glutReshapeFunc(resize);
glutDisplayFunc(render);
glutIdleFunc(idle);
glutTimerFunc(0, timer, 0);
glutCloseFunc(destroyCube);
}

/*
* rezie(width, height):
* Resize the openGL window.
*/
void resize(int width, int height) {
/* Save dimensions */
windowWidth = width;
windowHeight = height;

/* Set viewport */
glViewport(0, 0, width, height);

/* Change our projection matrix */
projectionMatrix = CreateProjectionMatrix(60,
(float)windowWidth / windowHeight, 1.0f, 100.0f);
glUseProgram(shaderIds[0]);
glUniformMatrix4fv(projMatUniLoc, 1, GL_FALSE, projectionMatrix.m);
glUseProgram(0);
}

/*
* render()
* Render our openGL scene.
*/
void render(void) {
++frames;

/* Clear screen */
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

/* Draw our cube */
drawCube();

/* Swap buffers and update display */
glutSwapBuffers();
glutPostRedisplay();
}

/*
* idle():
* Logic function.
*/
void idle(void) {
glutPostRedisplay();
}

/*
* timer(val):
* Timer to count FPS.
*/
void timer(int val) {
char fpsString[512];

if (val != 0) {
/* Allocate memory and copy string */
sprintf(fpsString, "%s: %d FPS @ %d x %d", WINDOW_TITLE,
frames * 4, windowWidth, windowHeight);

/* Set it as title */
glutSetWindowTitle(fpsString);
}

frames = 0;
glutTimerFunc(250, timer, 1);
}

/*
* createCube():
* Setup the cube.
*/
void createCube(void) {
const Vertex vertices[8] = {
{{-0.5f, -0.5f, 0.5f, 1}, {0, 0, 1, 1}},
{{-0.5f, 0.5f, 0.5f, 1}, {1, 0, 0, 1}},
{{0.5f, 0.5f, 0.5f, 1}, {0, 1, 0, 1}},
{{0.5f, -0.5f, 0.5f, 1}, {1, 1, 0, 1}},
{{-0.5f, -0.5f, -0.5f, 1}, {1, 1, 1, 1}},
{{-0.5f, 0.5f, -0.5f, 1}, {1, 0, 0, 1}},
{{0.5f, 0.5f, -0.5f, 1}, {1, 0, 1, 1}},
{{0.5f, -0.5f, -0.5f, 1}, {0, 0, 1, 1}}
};
const GLuint indices[36] = {
0, 2, 1, 0, 3, 2, 4, 3, 0, 4, 7, 3,
4, 1, 5, 4, 0, 1, 3, 6, 2, 3, 7, 6,
1, 6, 5, 1, 2, 6, 7, 5, 6, 7, 4, 5
};

/* Generate the shader program */
shaderIds[SHADER_PROGRAM] = glCreateProgram();
ExitOnGLError("ERROR: Could not create shader program");

/* Load and attach shaders */
shaderIds[SHADER_FRAGMENT] = LoadShader("fragment.glsl", GL_FRAGMENT_SHADER);
shaderIds[SHADER_VERTEX] = LoadShader("vertex.glsl", GL_VERTEX_SHADER);
glAttachShader(shaderIds[SHADER_PROGRAM], shaderIds[SHADER_FRAGMENT]);
glAttachShader(shaderIds[SHADER_PROGRAM], shaderIds[SHADER_VERTEX]);

/* Link shader program */
glLinkProgram(shaderIds[SHADER_PROGRAM]);
ExitOnGLError("ERROR: Could not link shader program");

/* Retrive shader uniforms */
modelMatUniLoc = glGetUniformLocation(shaderIds[SHADER_PROGRAM], "modelMatrix");
viewMatUniLoc = glGetUniformLocation(shaderIds[SHADER_PROGRAM], "viewMatrix");
projMatUniLoc = glGetUniformLocation(shaderIds[SHADER_PROGRAM], "projectionMatrix");
ExitOnGLError("ERROR: Could not get shader uniform locations");

/* Generate and bind our vertex array object */
glGenVertexArrays(1, &bufferIds[BUFFER_VAO]);
ExitOnGLError("ERROR: Could not generate VAO");
glBindVertexArray(bufferIds[BUFFER_VAO]);
ExitOnGLError("ERROR: Could not bind VAO");
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
ExitOnGLError("ERROR: Could not enable vertex attributes");

/* Bind VBO and send data */
glGenBuffers(2, &bufferIds[BUFFER_VBO]);
glBindBuffer(GL_ARRAY_BUFFER, bufferIds[BUFFER_VBO]);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
ExitOnGLError("ERROR: Could not bind VBO to VAO");

/* Set the attributes for our VAO */
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, sizeof(vertices[0]), (GLvoid *)0);
glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, sizeof(vertices[0]),
(GLvoid *)sizeof(vertices[0].Position));
ExitOnGLError("ERROR: Could not set VAO attributes");

/* Bind IBO and send data */
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, bufferIds[BUFFER_IBO]);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
ExitOnGLError("ERROR: Could not bind IBO to VAO");
glBindVertexArray(0);
}

/*
* destroyCube():
* Destroy out little cubie.
*/
void destroyCube(void) {
/* Detach and delete shaders */
glDetachShader(shaderIds[SHADER_PROGRAM], shaderIds[SHADER_FRAGMENT]);
glDetachShader(shaderIds[SHADER_PROGRAM], shaderIds[SHADER_VERTEX]);
glDeleteShader(shaderIds[SHADER_FRAGMENT]);
glDeleteShader(shaderIds[SHADER_VERTEX]);
glDeleteProgram(shaderIds[SHADER_PROGRAM]);
ExitOnGLError("ERROR: Could not destroy shaders");

/* Delete and destroy buffers */
glDeleteBuffers(2, &bufferIds[BUFFER_VBO]);
glDeleteVertexArrays(1, &bufferIds[BUFFER_VAO]);
ExitOnGLError("ERROR: Could not destroy buffer objects");
}

/*
* drawCube():
* Draw the cube.
*/
void drawCube(void) {
float cubeAngle;
clock_t now;

/* Current time */
now = clock();
if (lastTime == 0)
lastTime = now;

/* Adjust rotation */
cubeRotation += 45.0f * ((float)(now - lastTime) / CLOCKS_PER_SEC);
cubeAngle = DegreesToRadians(cubeRotation);
lastTime = now;

/* Rotate the matrix */
modelMatrix = IDENTITY_MATRIX;
RotateAboutY(&modelMatrix, cubeAngle);
RotateAboutX(&modelMatrix, cubeAngle);

/* Use the shader program so we can manipluate */
glUseProgram(shaderIds[SHADER_PROGRAM]);

/* Adjust matrix uniform locations */
glUniformMatrix4fv(modelMatUniLoc, 1, GL_FALSE, modelMatrix.m);
glUniformMatrix4fv(viewMatUniLoc, 1, GL_FALSE, viewMatrix.m);
ExitOnGLError("ERROR: Could not set the shader uniforms");

/* Bind and draw the VAO */
glBindVertexArray(bufferIds[BUFFER_VAO]);
ExitOnGLError("ERROR: Could not bind VAO for drawing");
glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, (GLvoid *)0);
ExitOnGLError("ERROR: Could not draw the cube");

/* Done manipulating */
glBindVertexArray(0);
glUseProgram(0);
}




Their code


/* Copyright (C) 2011 by Eddy Luten

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

#include "Utils.h"
#define WINDOW_TITLE_PREFIX "Chapter 4"

int CurrentWidth = 800,
CurrentHeight = 600,
WindowHandle = 0;

unsigned FrameCount = 0;

GLuint
ProjectionMatrixUniformLocation,
ViewMatrixUniformLocation,
ModelMatrixUniformLocation,
BufferIds[3] = { 0 },
ShaderIds[3] = { 0 };

Matrix
ProjectionMatrix,
ViewMatrix,
ModelMatrix;

float CubeRotation = 0;
clock_t LastTime = 0;

void Initialize(int, char*[]);
void InitWindow(int, char*[]);
void ResizeFunction(int, int);
void RenderFunction(void);
void TimerFunction(int);
void IdleFunction(void);
void CreateCube(void);
void DestroyCube(void);
void DrawCube(void);

int main(int argc, char* argv[])
{
Initialize(argc, argv);

glutMainLoop();

exit(EXIT_SUCCESS);
}

void Initialize(int argc, char* argv[])
{
GLenum GlewInitResult;

InitWindow(argc, argv);

glewExperimental = GL_TRUE;
GlewInitResult = glewInit();

if (GLEW_OK != GlewInitResult) {
fprintf(
stderr,
"ERROR: %s\n",
glewGetErrorString(GlewInitResult)
);
exit(EXIT_FAILURE);
}

fprintf(
stdout,
"INFO: OpenGL Version: %s\n",
glGetString(GL_VERSION)
);

glGetError();
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LESS);
ExitOnGLError("ERROR: Could not set OpenGL depth testing options");

glEnable(GL_CULL_FACE);
glCullFace(GL_BACK);
glFrontFace(GL_CCW);
ExitOnGLError("ERROR: Could not set OpenGL culling options");

ModelMatrix = IDENTITY_MATRIX;
ProjectionMatrix = IDENTITY_MATRIX;
ViewMatrix = IDENTITY_MATRIX;
TranslateMatrix(&ViewMatrix, 0, 0, -2);

CreateCube();
}

void InitWindow(int argc, char* argv[])
{
glutInit(&argc, argv);

glutInitContextVersion(4, 0);
glutInitContextFlags(GLUT_FORWARD_COMPATIBLE);
glutInitContextProfile(GLUT_CORE_PROFILE);

glutSetOption(
GLUT_ACTION_ON_WINDOW_CLOSE,
GLUT_ACTION_GLUTMAINLOOP_RETURNS
);

glutInitWindowSize(CurrentWidth, CurrentHeight);

glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);

WindowHandle = glutCreateWindow(WINDOW_TITLE_PREFIX);

if(WindowHandle < 1) {
fprintf(
stderr,
"ERROR: Could not create a new rendering window.\n"
);
exit(EXIT_FAILURE);
}

glutReshapeFunc(ResizeFunction);
glutDisplayFunc(RenderFunction);
glutIdleFunc(IdleFunction);
glutTimerFunc(0, TimerFunction, 0);
glutCloseFunc(DestroyCube);
}

void ResizeFunction(int Width, int Height)
{
CurrentWidth = Width;
CurrentHeight = Height;
glViewport(0, 0, CurrentWidth, CurrentHeight);
ProjectionMatrix =
CreateProjectionMatrix(
60,
(float)CurrentWidth / CurrentHeight,
1.0f,
100.0f
);

glUseProgram(ShaderIds[0]);
glUniformMatrix4fv(ProjectionMatrixUniformLocation, 1, GL_FALSE, ProjectionMatrix.m);
glUseProgram(0);
}

void RenderFunction(void)
{
++FrameCount;

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

DrawCube();

glutSwapBuffers();
glutPostRedisplay();
}

void IdleFunction(void)
{
glutPostRedisplay();
}

void TimerFunction(int Value)
{
if (0 != Value) {
char* TempString = (char*)
malloc(512 + strlen(WINDOW_TITLE_PREFIX));

sprintf(
TempString,
"%s: %d Frames Per Second @ %d x %d",
WINDOW_TITLE_PREFIX,
FrameCount * 4,
CurrentWidth,
CurrentHeight
);

glutSetWindowTitle(TempString);
free(TempString);
}

FrameCount = 0;
glutTimerFunc(250, TimerFunction, 1);
}

void CreateCube()
{
const Vertex VERTICES[8] =
{
{ { -.5f, -.5f, .5f, 1 }, { 0, 0, 1, 1 } },
{ { -.5f, .5f, .5f, 1 }, { 1, 0, 0, 1 } },
{ { .5f, .5f, .5f, 1 }, { 0, 1, 0, 1 } },
{ { .5f, -.5f, .5f, 1 }, { 1, 1, 0, 1 } },
{ { -.5f, -.5f, -.5f, 1 }, { 1, 1, 1, 1 } },
{ { -.5f, .5f, -.5f, 1 }, { 1, 0, 0, 1 } },
{ { .5f, .5f, -.5f, 1 }, { 1, 0, 1, 1 } },
{ { .5f, -.5f, -.5f, 1 }, { 0, 0, 1, 1 } }
};

const GLuint INDICES[36] =
{
0,2,1, 0,3,2,
4,3,0, 4,7,3,
4,1,5, 4,0,1,
3,6,2, 3,7,6,
1,6,5, 1,2,6,
7,5,6, 7,4,5
};

ShaderIds[0] = glCreateProgram();
ExitOnGLError("ERROR: Could not create the shader program");
{
ShaderIds[1] = LoadShader("SimpleShader.fragment.glsl", GL_FRAGMENT_SHADER);
ShaderIds[2] = LoadShader("SimpleShader.vertex.glsl", GL_VERTEX_SHADER);
glAttachShader(ShaderIds[0], ShaderIds[1]);
glAttachShader(ShaderIds[0], ShaderIds[2]);
}
glLinkProgram(ShaderIds[0]);
ExitOnGLError("ERROR: Could not link the shader program");

ModelMatrixUniformLocation = glGetUniformLocation(ShaderIds[0], "ModelMatrix");
ViewMatrixUniformLocation = glGetUniformLocation(ShaderIds[0], "ViewMatrix");
ProjectionMatrixUniformLocation = glGetUniformLocation(ShaderIds[0], "ProjectionMatrix");
ExitOnGLError("ERROR: Could not get shader uniform locations");

glGenVertexArrays(1, &BufferIds[0]);
ExitOnGLError("ERROR: Could not generate the VAO");
glBindVertexArray(BufferIds[0]);
ExitOnGLError("ERROR: Could not bind the VAO");

glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
ExitOnGLError("ERROR: Could not enable vertex attributes");

glGenBuffers(2, &BufferIds[1]);
ExitOnGLError("ERROR: Could not generate the buffer objects");

glBindBuffer(GL_ARRAY_BUFFER, BufferIds[1]);
glBufferData(GL_ARRAY_BUFFER, sizeof(VERTICES), VERTICES, GL_STATIC_DRAW);
ExitOnGLError("ERROR: Could not bind the VBO to the VAO");

glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, sizeof(VERTICES[0]), (GLvoid*)0);
glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, sizeof(VERTICES[0]), (GLvoid*)sizeof(VERTICES[0].Position));
ExitOnGLError("ERROR: Could not set VAO attributes");

glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, BufferIds[2]);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(INDICES), INDICES, GL_STATIC_DRAW);
ExitOnGLError("ERROR: Could not bind the IBO to the VAO");

glBindVertexArray(0);
}

void DestroyCube()
{
glDetachShader(ShaderIds[0], ShaderIds[1]);
glDetachShader(ShaderIds[0], ShaderIds[2]);
glDeleteShader(ShaderIds[1]);
glDeleteShader(ShaderIds[2]);
glDeleteProgram(ShaderIds[0]);
ExitOnGLError("ERROR: Could not destroy the shaders");

glDeleteBuffers(2, &BufferIds[1]);
glDeleteVertexArrays(1, &BufferIds[0]);
ExitOnGLError("ERROR: Could not destroy the buffer objects");
}

void DrawCube(void)
{
float CubeAngle;
clock_t Now = clock();

if (LastTime == 0)
LastTime = Now;

CubeRotation += 45.0f * ((float)(Now - LastTime) / CLOCKS_PER_SEC);
CubeAngle = DegreesToRadians(CubeRotation);
LastTime = Now;

ModelMatrix = IDENTITY_MATRIX;
RotateAboutY(&ModelMatrix, CubeAngle);
RotateAboutX(&ModelMatrix, CubeAngle);

glUseProgram(ShaderIds[0]);
ExitOnGLError("ERROR: Could not use the shader program");

glUniformMatrix4fv(ModelMatrixUniformLocation, 1, GL_FALSE, ModelMatrix.m);
glUniformMatrix4fv(ViewMatrixUniformLocation, 1, GL_FALSE, ViewMatrix.m);
ExitOnGLError("ERROR: Could not set the shader uniforms");

glBindVertexArray(BufferIds[0]);
ExitOnGLError("ERROR: Could not bind the VAO for drawing purposes");

glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, (GLvoid*)0);
ExitOnGLError("ERROR: Could not draw the cube");

glBindVertexArray(0);
glUseProgram(0);
}

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Hello again folks, thank you for the fast answers!

I'm not getting any error outputs at all. The thing that "doesn't work" is that the screen is entierly black. The nice little cube is missing.

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Can you post your shaders as well? For one thing its not good to use hardcoded indexes (0/1) for your attribs. You should query the attribute indexes for your shader inputs via glGetAttribLocation, then use the returned value to index it.

I'm not sure you can just assume you can always assign 0 to vertex position unless you're using deprecated shader builtin variables, which I don't know if you are or not.

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I'm using the same shaders as the example that works:

Vertex:


#version 400

layout(location=0) in vec4 in_Position;
layout(location=1) in vec4 in_Color;
out vec4 ex_Color;

uniform mat4 ModelMatrix;
uniform mat4 ViewMatrix;
uniform mat4 ProjectionMatrix;

void main(void)
{
gl_Position = (ProjectionMatrix * ViewMatrix * ModelMatrix) * in_Position;
ex_Color = in_Color;
}


Fragment:


#version 400

in vec4 ex_Color;
out vec4 out_Color;

void main(void)
{
out_Color = ex_Color;
}

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You changed the casing in your call to glGetUniformLocation to lower camel case ([color=#660066][font=CourierNew, monospace][size=2]modelMatrix[/font]), while the names of the uniforms in the shaders remain upper camel case ([color=#660066][font=CourierNew, monospace][size=2]ModelMatrix[/font]), that may be why it's not working. Let me know.

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Thank you, that was the problem!

I'd also like to thank you for those awesome guides. They are very helpfull and well written <3

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I even didn't know that such website exists.
Will there be more than 4 chapters?

Or that's all?
Big .com website for only 4 chapters is pretty expensive.


But if you're going to expand it, then it's good.

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The OpenGLBook.com website is awesome. I've gotten a much better understanding of shaders in general thanks to the help i've gotten from it.

I'd love to see more chapters! :)

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[font="arial, verdana, tahoma, sans-serif"]More chapters are under way, just not sure when I'll be releasing them yet. I've been busy with other projects lately and haven't had much time for this or other hobbies. I'm sorry to have kept you and others waiting, I hope to be getting back on track one day soon.

Big .com website for only 4 chapters is pretty expensive.

[color="#1C2837"]"Expensive" is a relative term, and I would like to point out that IMHO the length and breadth of the chapters is a bit more than your regular OpenGL"triangle" tutorial. I could split the 4 chapters up into 8 or more smaller tutorials if that justifies the existence of the site more in your eyes. ;)[/font][color="#1c2837"]

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      As it was mentioned earlier, Diligent Engine follows next-gen APIs to configure the graphics/compute pipeline. One big Pipelines State Object (PSO) encompasses all required states (all shader stages, input layout description, depth stencil, rasterizer and blend state descriptions etc.). This approach maps directly to Direct3D12/Vulkan, but is also beneficial for older APIs as it eliminates pipeline misconfiguration errors. With many individual calls tweaking various GPU pipeline settings it is very easy to forget to set one of the states or assume the stage is already properly configured when in fact it is not. Using pipeline state object helps avoid these problems as all stages are configured at once.
      Creating Shaders
      While in earlier APIs shaders were bound separately, in the next-generation APIs as well as in Diligent Engine shaders are part of the pipeline state object. The biggest challenge when authoring shaders is that Direct3D and OpenGL/Vulkan use different shader languages (while Apple uses yet another language in their Metal API). Maintaining two versions of every shader is not an option for real applications and Diligent Engine implements shader source code converter that allows shaders authored in HLSL to be translated to GLSL. To create a shader, one needs to populate ShaderCreationAttribs structure. SourceLanguage member of this structure tells the system which language the shader is authored in:
      SHADER_SOURCE_LANGUAGE_DEFAULT - The shader source language matches the underlying graphics API: HLSL for Direct3D11/Direct3D12 mode, and GLSL for OpenGL and OpenGLES modes. SHADER_SOURCE_LANGUAGE_HLSL - The shader source is in HLSL. For OpenGL and OpenGLES modes, the source code will be converted to GLSL. SHADER_SOURCE_LANGUAGE_GLSL - The shader source is in GLSL. There is currently no GLSL to HLSL converter, so this value should only be used for OpenGL and OpenGLES modes. There are two ways to provide the shader source code. The first way is to use Source member. The second way is to provide a file path in FilePath member. Since the engine is entirely decoupled from the platform and the host file system is platform-dependent, the structure exposes pShaderSourceStreamFactory member that is intended to provide the engine access to the file system. If FilePath is provided, shader source factory must also be provided. If the shader source contains any #include directives, the source stream factory will also be used to load these files. The engine provides default implementation for every supported platform that should be sufficient in most cases. Custom implementation can be provided when needed.
      When sampling a texture in a shader, the texture sampler was traditionally specified as separate object that was bound to the pipeline at run time or set as part of the texture object itself. However, in most cases it is known beforehand what kind of sampler will be used in the shader. Next-generation APIs expose new type of sampler called static sampler that can be initialized directly in the pipeline state. Diligent Engine exposes this functionality: when creating a shader, textures can be assigned static samplers. If static sampler is assigned, it will always be used instead of the one initialized in the texture shader resource view. To initialize static samplers, prepare an array of StaticSamplerDesc structures and initialize StaticSamplers and NumStaticSamplers members. Static samplers are more efficient and it is highly recommended to use them whenever possible. On older APIs, static samplers are emulated via generic sampler objects.
      The following is an example of shader initialization:
      ShaderCreationAttribs Attrs; Attrs.Desc.Name = "MyPixelShader"; Attrs.FilePath = "MyShaderFile.fx"; Attrs.SearchDirectories = "shaders;shaders\\inc;"; Attrs.EntryPoint = "MyPixelShader"; Attrs.Desc.ShaderType = SHADER_TYPE_PIXEL; Attrs.SourceLanguage = SHADER_SOURCE_LANGUAGE_HLSL; BasicShaderSourceStreamFactory BasicSSSFactory(Attrs.SearchDirectories); Attrs.pShaderSourceStreamFactory = &BasicSSSFactory; ShaderVariableDesc ShaderVars[] = {     {"g_StaticTexture", SHADER_VARIABLE_TYPE_STATIC},     {"g_MutableTexture", SHADER_VARIABLE_TYPE_MUTABLE},     {"g_DynamicTexture", SHADER_VARIABLE_TYPE_DYNAMIC} }; Attrs.Desc.VariableDesc = ShaderVars; Attrs.Desc.NumVariables = _countof(ShaderVars); Attrs.Desc.DefaultVariableType = SHADER_VARIABLE_TYPE_STATIC; StaticSamplerDesc StaticSampler; StaticSampler.Desc.MinFilter = FILTER_TYPE_LINEAR; StaticSampler.Desc.MagFilter = FILTER_TYPE_LINEAR; StaticSampler.Desc.MipFilter = FILTER_TYPE_LINEAR; StaticSampler.TextureName = "g_MutableTexture"; Attrs.Desc.NumStaticSamplers = 1; Attrs.Desc.StaticSamplers = &StaticSampler; ShaderMacroHelper Macros; Macros.AddShaderMacro("USE_SHADOWS", 1); Macros.AddShaderMacro("NUM_SHADOW_SAMPLES", 4); Macros.Finalize(); Attrs.Macros = Macros; RefCntAutoPtr<IShader> pShader; m_pDevice->CreateShader( Attrs, &pShader );
      Creating the Pipeline State Object
      After all required shaders are created, the rest of the fields of the PipelineStateDesc structure provide depth-stencil, rasterizer, and blend state descriptions, the number and format of render targets, input layout format, etc. For instance, rasterizer state can be described as follows:
      PipelineStateDesc PSODesc; RasterizerStateDesc &RasterizerDesc = PSODesc.GraphicsPipeline.RasterizerDesc; RasterizerDesc.FillMode = FILL_MODE_SOLID; RasterizerDesc.CullMode = CULL_MODE_NONE; RasterizerDesc.FrontCounterClockwise = True; RasterizerDesc.ScissorEnable = True; RasterizerDesc.AntialiasedLineEnable = False; Depth-stencil and blend states are defined in a similar fashion.
      Another important thing that pipeline state object encompasses is the input layout description that defines how inputs to the vertex shader, which is the very first shader stage, should be read from the memory. Input layout may define several vertex streams that contain values of different formats and sizes:
      // Define input layout InputLayoutDesc &Layout = PSODesc.GraphicsPipeline.InputLayout; LayoutElement TextLayoutElems[] = {     LayoutElement( 0, 0, 3, VT_FLOAT32, False ),     LayoutElement( 1, 0, 4, VT_UINT8, True ),     LayoutElement( 2, 0, 2, VT_FLOAT32, False ), }; Layout.LayoutElements = TextLayoutElems; Layout.NumElements = _countof( TextLayoutElems ); Finally, pipeline state defines primitive topology type. When all required members are initialized, a pipeline state object can be created by IRenderDevice::CreatePipelineState() method:
      // Define shader and primitive topology PSODesc.GraphicsPipeline.PrimitiveTopologyType = PRIMITIVE_TOPOLOGY_TYPE_TRIANGLE; PSODesc.GraphicsPipeline.pVS = pVertexShader; PSODesc.GraphicsPipeline.pPS = pPixelShader; PSODesc.Name = "My pipeline state"; m_pDev->CreatePipelineState(PSODesc, &m_pPSO); When PSO object is bound to the pipeline, the engine invokes all API-specific commands to set all states specified by the object. In case of Direct3D12 this maps directly to setting the D3D12 PSO object. In case of Direct3D11, this involves setting individual state objects (such as rasterizer and blend states), shaders, input layout etc. In case of OpenGL, this requires a number of fine-grain state tweaking calls. Diligent Engine keeps track of currently bound states and only calls functions to update these states that have actually changed.
      Binding Shader Resources
      Direct3D11 and OpenGL utilize fine-grain resource binding models, where an application binds individual buffers and textures to certain shader or program resource binding slots. Direct3D12 uses a very different approach, where resource descriptors are grouped into tables, and an application can bind all resources in the table at once by setting the table in the command list. Resource binding model in Diligent Engine is designed to leverage this new method. It introduces a new object called shader resource binding that encapsulates all resource bindings required for all shaders in a certain pipeline state. It also introduces the classification of shader variables based on the frequency of expected change that helps the engine group them into tables under the hood:
      Static variables (SHADER_VARIABLE_TYPE_STATIC) are variables that are expected to be set only once. They may not be changed once a resource is bound to the variable. Such variables are intended to hold global constants such as camera attributes or global light attributes constant buffers. Mutable variables (SHADER_VARIABLE_TYPE_MUTABLE) define resources that are expected to change on a per-material frequency. Examples may include diffuse textures, normal maps etc. Dynamic variables (SHADER_VARIABLE_TYPE_DYNAMIC) are expected to change frequently and randomly. Shader variable type must be specified during shader creation by populating an array of ShaderVariableDesc structures and initializing ShaderCreationAttribs::Desc::VariableDesc and ShaderCreationAttribs::Desc::NumVariables members (see example of shader creation above).
      Static variables cannot be changed once a resource is bound to the variable. They are bound directly to the shader object. For instance, a shadow map texture is not expected to change after it is created, so it can be bound directly to the shader:
      PixelShader->GetShaderVariable( "g_tex2DShadowMap" )->Set( pShadowMapSRV ); Mutable and dynamic variables are bound via a new Shader Resource Binding object (SRB) that is created by the pipeline state (IPipelineState::CreateShaderResourceBinding()):
      m_pPSO->CreateShaderResourceBinding(&m_pSRB); Note that an SRB is only compatible with the pipeline state it was created from. SRB object inherits all static bindings from shaders in the pipeline, but is not allowed to change them.
      Mutable resources can only be set once for every instance of a shader resource binding. Such resources are intended to define specific material properties. For instance, a diffuse texture for a specific material is not expected to change once the material is defined and can be set right after the SRB object has been created:
      m_pSRB->GetVariable(SHADER_TYPE_PIXEL, "tex2DDiffuse")->Set(pDiffuseTexSRV); In some cases it is necessary to bind a new resource to a variable every time a draw command is invoked. Such variables should be labeled as dynamic, which will allow setting them multiple times through the same SRB object:
      m_pSRB->GetVariable(SHADER_TYPE_VERTEX, "cbRandomAttribs")->Set(pRandomAttrsCB); Under the hood, the engine pre-allocates descriptor tables for static and mutable resources when an SRB objcet is created. Space for dynamic resources is dynamically allocated at run time. Static and mutable resources are thus more efficient and should be used whenever possible.
      As you can see, Diligent Engine does not expose low-level details of how resources are bound to shader variables. One reason for this is that these details are very different for various APIs. The other reason is that using low-level binding methods is extremely error-prone: it is very easy to forget to bind some resource, or bind incorrect resource such as bind a buffer to the variable that is in fact a texture, especially during shader development when everything changes fast. Diligent Engine instead relies on shader reflection system to automatically query the list of all shader variables. Grouping variables based on three types mentioned above allows the engine to create optimized layout and take heavy lifting of matching resources to API-specific resource location, register or descriptor in the table.
      This post gives more details about the resource binding model in Diligent Engine.
      Setting the Pipeline State and Committing Shader Resources
      Before any draw or compute command can be invoked, the pipeline state needs to be bound to the context:
      m_pContext->SetPipelineState(m_pPSO); Under the hood, the engine sets the internal PSO object in the command list or calls all the required native API functions to properly configure all pipeline stages.
      The next step is to bind all required shader resources to the GPU pipeline, which is accomplished by IDeviceContext::CommitShaderResources() method:
      m_pContext->CommitShaderResources(m_pSRB, COMMIT_SHADER_RESOURCES_FLAG_TRANSITION_RESOURCES); The method takes a pointer to the shader resource binding object and makes all resources the object holds available for the shaders. In the case of D3D12, this only requires setting appropriate descriptor tables in the command list. For older APIs, this typically requires setting all resources individually.
      Next-generation APIs require the application to track the state of every resource and explicitly inform the system about all state transitions. For instance, if a texture was used as render target before, while the next draw command is going to use it as shader resource, a transition barrier needs to be executed. Diligent Engine does the heavy lifting of state tracking.  When CommitShaderResources() method is called with COMMIT_SHADER_RESOURCES_FLAG_TRANSITION_RESOURCES flag, the engine commits and transitions resources to correct states at the same time. Note that transitioning resources does introduce some overhead. The engine tracks state of every resource and it will not issue the barrier if the state is already correct. But checking resource state is an overhead that can sometimes be avoided. The engine provides IDeviceContext::TransitionShaderResources() method that only transitions resources:
      m_pContext->TransitionShaderResources(m_pPSO, m_pSRB); In some scenarios it is more efficient to transition resources once and then only commit them.
      Invoking Draw Command
      The final step is to set states that are not part of the PSO, such as render targets, vertex and index buffers. Diligent Engine uses Direct3D11-syle API that is translated to other native API calls under the hood:
      ITextureView *pRTVs[] = {m_pRTV}; m_pContext->SetRenderTargets(_countof( pRTVs ), pRTVs, m_pDSV); // Clear render target and depth buffer const float zero[4] = {0, 0, 0, 0}; m_pContext->ClearRenderTarget(nullptr, zero); m_pContext->ClearDepthStencil(nullptr, CLEAR_DEPTH_FLAG, 1.f); // Set vertex and index buffers IBuffer *buffer[] = {m_pVertexBuffer}; Uint32 offsets[] = {0}; Uint32 strides[] = {sizeof(MyVertex)}; m_pContext->SetVertexBuffers(0, 1, buffer, strides, offsets, SET_VERTEX_BUFFERS_FLAG_RESET); m_pContext->SetIndexBuffer(m_pIndexBuffer, 0); Different native APIs use various set of function to execute draw commands depending on command details (if the command is indexed, instanced or both, what offsets in the source buffers are used etc.). For instance, there are 5 draw commands in Direct3D11 and more than 9 commands in OpenGL with something like glDrawElementsInstancedBaseVertexBaseInstance not uncommon. Diligent Engine hides all details with single IDeviceContext::Draw() method that takes takes DrawAttribs structure as an argument. The structure members define all attributes required to perform the command (primitive topology, number of vertices or indices, if draw call is indexed or not, if draw call is instanced or not, if draw call is indirect or not, etc.). For example:
      DrawAttribs attrs; attrs.IsIndexed = true; attrs.IndexType = VT_UINT16; attrs.NumIndices = 36; attrs.Topology = PRIMITIVE_TOPOLOGY_TRIANGLE_LIST; pContext->Draw(attrs); For compute commands, there is IDeviceContext::DispatchCompute() method that takes DispatchComputeAttribs structure that defines compute grid dimension.
      Source Code
      Full engine source code is available on GitHub and is free to use. The repository contains tutorials, sample applications, asteroids performance benchmark and an example Unity project that uses Diligent Engine in native plugin.
      Atmospheric scattering sample demonstrates how Diligent Engine can be used to implement various rendering tasks: loading textures from files, using complex shaders, rendering to multiple render targets, using compute shaders and unordered access views, etc.

      Asteroids performance benchmark is based on this demo developed by Intel. It renders 50,000 unique textured asteroids and allows comparing performance of Direct3D11 and Direct3D12 implementations. Every asteroid is a combination of one of 1000 unique meshes and one of 10 unique textures.

      Finally, there is an example project that shows how Diligent Engine can be integrated with Unity.

      Future Work
      The engine is under active development. It currently supports Windows desktop, Universal Windows, Linux, Android, MacOS, and iOS platforms. Direct3D11, Direct3D12, OpenGL/GLES backends are now feature complete. Vulkan backend is coming next, and Metal backend is in the plan.
    • By LifeArtist
      Good Evening,
      I want to make a 2D game which involves displaying some debug information. Especially for collision, enemy sights and so on ...
      First of I was thinking about all those shapes which I need will need for debugging purposes: circles, rectangles, lines, polygons.
      I am really stucked right now because of the fundamental question:
      Where do I store my vertices positions for each line (object)? Currently I am not using a model matrix because I am using orthographic projection and set the final position within the VBO. That means that if I add a new line I would have to expand the "points" array and re-upload (recall glBufferData) it every time. The other method would be to use a model matrix and a fixed vbo for a line but it would be also messy to exactly create a line from (0,0) to (100,20) calculating the rotation and scale to make it fit.
      If I proceed with option 1 "updating the array each frame" I was thinking of having 4 draw calls every frame for the lines vao, polygons vao and so on. 
      In addition to that I am planning to use some sort of ECS based architecture. So the other question would be:
      Should I treat those debug objects as entities/components?
      For me it would make sense to treat them as entities but that's creates a new issue with the previous array approach because it would have for example a transform and render component. A special render component for debug objects (no texture etc) ... For me the transform component is also just a matrix but how would I then define a line?
      Treating them as components would'nt be a good idea in my eyes because then I would always need an entity. Well entity is just an id !? So maybe its a component?
      Regards,
      LifeArtist
    • By QQemka
      Hello. I am coding a small thingy in my spare time. All i want to achieve is to load a heightmap (as the lowest possible walking terrain), some static meshes (elements of the environment) and a dynamic character (meaning i can move, collide with heightmap/static meshes and hold a varying item in a hand ). Got a bunch of questions, or rather problems i can't find solution to myself. Nearly all are deal with graphics/gpu, not the coding part. My c++ is on high enough level.
      Let's go:
      Heightmap - i obviously want it to be textured, size is hardcoded to 256x256 squares. I can't have one huge texture stretched over entire terrain cause every pixel would be enormous. Thats why i decided to use 2 specified textures. First will be a tileset consisting of 16 square tiles (u v range from 0 to 0.25 for first tile and so on) and second a 256x256 buffer with 0-15 value representing index of the tile from tileset for every heigtmap square. Problem is, how do i blend the edges nicely and make some computationally cheap changes so its not obvious there are only 16 tiles? Is it possible to generate such terrain with some existing program?
      Collisions - i want to use bounding sphere and aabb. But should i store them for a model or entity instance? Meaning i have 20 same trees spawned using the same tree model, but every entity got its own transformation (position, scale etc). Storing collision component per instance grats faster access + is precalculated and transformed (takes additional memory, but who cares?), so i stick with this, right? What should i do if object is dynamically rotated? The aabb is no longer aligned and calculating per vertex min/max everytime object rotates/scales is pretty expensive, right?
      Drawing aabb - problem similar to above (storing aabb data per instance or model). This time in my opinion per model is enough since every instance also does not have own vertex buffer but uses the shared one (so 20 trees share reference to one tree model). So rendering aabb is about taking the model's aabb, transforming with instance matrix and voila. What about aabb vertex buffer (this is more of a cosmetic question, just curious, bumped onto it in time of writing this). Is it better to make it as 8 points and index buffer (12 lines), or only 2 vertices with min/max x/y/z and having the shaders dynamically generate 6 other vertices and draw the box? Or maybe there should be just ONE 1x1x1 cube box template moved/scaled per entity?
      What if one model got a diffuse texture and a normal map, and other has only diffuse? Should i pass some bool flag to shader with that info, or just assume that my game supports only diffuse maps without fancy stuff?
      There were several more but i forgot/solved them at time of writing
      Thanks in advance
    • By RenanRR
      Hi All,
      I'm reading the tutorials from learnOpengl site (nice site) and I'm having a question on the camera (https://learnopengl.com/Getting-started/Camera).
      I always saw the camera being manipulated with the lookat, but in tutorial I saw the camera being changed through the MVP arrays, which do not seem to be camera, but rather the scene that changes:
      Vertex Shader:
      #version 330 core layout (location = 0) in vec3 aPos; layout (location = 1) in vec2 aTexCoord; out vec2 TexCoord; uniform mat4 model; uniform mat4 view; uniform mat4 projection; void main() { gl_Position = projection * view * model * vec4(aPos, 1.0f); TexCoord = vec2(aTexCoord.x, aTexCoord.y); } then, the matrix manipulated:
      ..... glm::mat4 projection = glm::perspective(glm::radians(fov), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f); ourShader.setMat4("projection", projection); .... glm::mat4 view = glm::lookAt(cameraPos, cameraPos + cameraFront, cameraUp); ourShader.setMat4("view", view); .... model = glm::rotate(model, glm::radians(angle), glm::vec3(1.0f, 0.3f, 0.5f)); ourShader.setMat4("model", model);  
      So, some doubts:
      - Why use it like that?
      - Is it okay to manipulate the camera that way?
      -in this way, are not the vertex's positions that changes instead of the camera?
      - I need to pass MVP to all shaders of object in my scenes ?
       
      What it seems, is that the camera stands still and the scenery that changes...
      it's right?
       
       
      Thank you
       
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