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xmllmx

OpenGL Why could I not implement multisampling?

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Hello all, I encountered a strange problem when I was writing an OpenGL application. I wanted to implement the fullscreen antialiase effect(FSAA), and I've been using glut library. According to the Red Book, I wrote code like this: glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_MULTISAMPLE); glEnable(GLUT_MULTISAMPLE); Nevertheless, I could not see any improvement of the display quality. What's the reason? PS: My video card is nVidia 6600. The OpenGL library is version 2.0. The GLUT library is version 3.7. [Edited by - xmllmx on June 27, 2006 4:46:25 AM]

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http://developer.nvidia.com/object/gdc_ogl_multisample.html

http://nehe.gamedev.net/data/lessons/lesson.asp?lesson=46

HTH

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Thank you, MARS_999,

Before I launched this thread, I had found and visited the links you gave above, but they didn't answer my question.

The nVidia's ppt neither explain what multisampling is in detail nor give sample code.

Nehe's sample code doesn't use GLUT library. I just want to know why it doesn't work if I use GLUT library.

Do you have any explaination else? A complete sample code using GLUT will be the best one. Thanks in advance.

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try this


/* Copyright (c) Mark J. Kilgard, 1997. */

/* This program is freely distributable without licensing fees and is
provided without guarantee or warrantee expressed or implied. This
program is -not- in the public domain. */


/* This program demonstrates virtualization of OpenGL's lights. The idea is
that if an object is lit by many lights, it is computationally more
efficient to calculate the approximate lighting contribution of the
various lights per-object and only enable the "brightest" lights while
rendering the object. This also lets you render scenes with more lights
than the OpenGL implementation light (usually 8). Two approaches are
used: The "distance-based" approach only enables the 8 closest lights
based purely on distance. The "Lambertian-based" approach accounts for
diffuse lighting contributions and approximates the diffuse contribution. */


#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <GL/glut.h>

/* Some <math.h> files do not define M_PI... */
#ifndef M_PI
#define M_PI 3.14159265
#endif

#define MIN_VALUE(a,b) (((a)<(b))?(a):(b))
#define MAX_VALUE(a,b) (((a)>(b))?(a):(b))

enum {
DL_LIGHT_SPHERE = 1,
DL_BIG_SPHERE = 2,
DL_ICO = 3
};

enum {
M_SPHERE, M_ICO, M_LABELS, M_LINEAR, M_QUAD, M_REPORT_SIG,
M_LAMBERTIAN, M_DISTANCE, M_TIME
};

typedef struct _LightInfo {
GLfloat xyz[4];
GLfloat *rgb;
int enable;
} LightInfo;

typedef struct _LightBrightness {
int num;
GLfloat brightness;
} LightBrightness;

static int animation = 1;
static int labelLights = 1;
static int reportLightSignificance = 0;
static int brightnessModel = M_LAMBERTIAN;
static int numActiveLights;
static int timeFrames = 0;
static int singleBuffer = 0;
/* *INDENT-OFF* */

static GLfloat modelAmb[4] = {0.1, 0.1, 0.1, 1.0};
static GLfloat matAmb[4] = {0.2, 0.2, 0.2, 1.0};
static GLfloat matDiff[4] = {0.8, 0.8, 0.8, 1.0};
static GLfloat matSpec[4] = {0.4, 0.4, 0.4, 1.0};
static GLfloat matEmission[4] = {0.0, 0.0, 0.0, 1.0};

GLfloat red[] = {1.0, 0.0, 0.0, 1.0};
GLfloat green[] = {0.0, 1.0, 0.0, 1.0};
GLfloat blue[] = {0.0, 0.0, 1.0, 1.0};
GLfloat yellow[] = {1.0, 1.0, 0.0, 1.0};
GLfloat magenta[] = {1.0, 0.0, 1.0, 1.0};
GLfloat white[] = {1.0, 1.0, 1.0, 1.0};
GLfloat dim[] = {0.5, 0.5, 0.5, 1.0};

LightInfo linfo[] = {
{ {-4.0, 0.0, -10.0, 1.0}, yellow},
{ {4.0, 0.0, -10.0, 1.0}, green},
{ {-4.0, 0.0, -6.0, 1.0}, red},
{ {4.0, 0.0, -6.0, 1.0}, blue},
{ {-4.0, 0.0, -2.0, 1.0}, green},
{ {4.0, 0.0, -2.0, 1.0}, yellow},
{ {-4.0, 0.0, 2.0, 1.0}, blue},
{ {4.0, 0.0, 2.0, 1.0}, red},
{ {-4.0, 0.0, 6.0, 1.0}, yellow},
{ {4.0, 0.0, 6.0, 1.0}, green},
{ {-4.0, 0.0, 10.0, 1.0}, red},
{ {4.0, 0.0, 10.0, 1.0}, blue},
};

int lightState[8] = {1, 1, 1, 1, 1, 1, 1, 1};
/* *INDENT-ON* */

#define MAX_LIGHTS (sizeof(linfo)/sizeof(linfo[0]))

int moving = 0, begin;
GLfloat angle = 0.0;
int object = M_SPHERE;
int attenuation = M_QUAD;
GLfloat t = 0.0;

void
initLight(int num)
{
glLightf(GL_LIGHT0 + num, GL_CONSTANT_ATTENUATION, 0.0);
if (attenuation == M_LINEAR) {
glLightf(GL_LIGHT0 + num, GL_LINEAR_ATTENUATION, 0.4);
glLightf(GL_LIGHT0 + num, GL_QUADRATIC_ATTENUATION, 0.0);
} else {
glLightf(GL_LIGHT0 + num, GL_LINEAR_ATTENUATION, 0.0);
glLightf(GL_LIGHT0 + num, GL_QUADRATIC_ATTENUATION, 0.1);
}
glLightfv(GL_LIGHT0 + num, GL_SPECULAR, dim);
}

/* Draw a sphere the same color as the light at the light position so it is
easy to tell where the positional light sources are. */

void
drawLight(LightInfo * info)
{
glPushMatrix();
glTranslatef(info->xyz[0], info->xyz[1], info->xyz[2]);
glColor3fv(info->rgb);
glCallList(DL_LIGHT_SPHERE);
glPopMatrix();
}

/* Place the light's OpenGL light number next to the light's sphere. To
ensure a readable number with good contrast, a black version of the number
is drawn shifted a pixel to the left and right of the actual white number.
*/

void
labelLight(LightInfo * info, int num)
{
GLubyte nothin = 0;
void *font = GLUT_BITMAP_HELVETICA_18;
int width = glutBitmapWidth(font, '0' + num);

glPushMatrix();
glColor3f(0.0, 0.0, 0.0);
glRasterPos3f(info->xyz[0], info->xyz[1], info->xyz[2]);
glBitmap(1, 1, 0, 0, 4, 5, &nothin);
glutBitmapCharacter(font, '0' + num);

glBitmap(1, 1, 0, 0, 2 - width, 0, &nothin);
glutBitmapCharacter(font, '0' + num);

if (lightState[num]) {
glColor3fv(white);
} else {
/* Draw disabled lights dimmer. */
glColor3fv(dim);
}
glRasterPos3f(info->xyz[0], info->xyz[1], info->xyz[2]);
glBitmap(1, 1, 0, 0, 5, 5, &nothin);
glutBitmapCharacter(font, '0' + num);
glPopMatrix();
}

/* Comparison routine used by qsort. */
int
lightBrightnessCompare(const void *a, const void *b)
{
LightBrightness *ld1 = (LightBrightness *) a;
LightBrightness *ld2 = (LightBrightness *) b;
GLfloat diff;

/* The brighter lights get sorted close to top of the list. */
diff = ld2->brightness - ld1->brightness;

if (diff > 0)
return 1;
if (diff < 0)
return -1;
return 0;
}

void
display(void)
{
int i;
GLfloat x, y, z;
LightBrightness ld[MAX_LIGHTS];
int start, end;

if (timeFrames) {
start = glutGet(GLUT_ELAPSED_TIME);
}
x = cos(t * 12.3) * 2.0;
y = 0.0;
z = sin(t) * 7.0;

for (i = 0; i < MAX_LIGHTS; i++) {
GLfloat dx, dy, dz;
GLfloat quadraticAttenuation;

/* Calculate object to light position vector. */
dx = (linfo.xyz[0] - x);
dy = (linfo.xyz[1] - y);
dz = (linfo.xyz[2] - z);

quadraticAttenuation = dx * dx + dy * dy + dz * dz;

if (brightnessModel == M_LAMBERTIAN) {
/* Lambertian surface-based brightness determination. */
GLfloat ex, ey, ez;
GLfloat nx, ny, nz;
GLfloat distance;
GLfloat diffuseReflection;

/* Determine eye point location (remember we can rotate by angle). */
ex = 16.0 * sin(angle * M_PI / 180.0);
ey = 1.0;
ez = 16.0 * -cos(angle * M_PI / 180.0);

/* Calculated normalized object to eye position direction (nx,ny,nz). */
nx = (ex - x);
ny = (ey - y);
nz = (ez - z);
distance = sqrt(nx * nx + ny * ny + nz * nz);
nx = nx / distance;
ny = ny / distance;
nz = nz / distance;

/* True distance needed, take square root. */
distance = sqrt(quadraticAttenuation);

/* Calculate normalized object to light postition direction (dx,dy,dz).
*/

dx = dx / distance;
dy = dy / distance;
dz = dz / distance;

/* Dot product of object->eye and object->light source directions.
OpenGL's lighting equations actually force the diffuse contribution
to be zero if the dot product is less than zero. For our purposes,
that's too strict since we are approximating the entire object with
a single object-to-eye normal. */

diffuseReflection = nx * dx + ny * dy + nz * dz;
if (attenuation == M_QUAD) {
/* Attenuate based on square of distance. */
ld.brightness = diffuseReflection / quadraticAttenuation;
} else {
/* Attenuate based on linear distance. */
ld.brightness = diffuseReflection / distance;
}
} else {
/* Distance-based brightness determination. */

/* In theory, we are really determining brightness based on just the
linear distance of the light source, but since we are just doing
comparisons, there is no reason to waste time doing a square root. */


/* Negation makes sure closer distances are "bigger" than further
distances for sorting. */

ld.brightness = -quadraticAttenuation;
}
ld.num = i;
}

/* Sort the lights so that the "brightest" are listed first. We really
want to just determine the first numActiveLights so a full sort is
overkill. */

qsort(ld, MAX_LIGHTS, sizeof(ld[0]), lightBrightnessCompare);

if (reportLightSignificance) {
printf("\n");
for (i = 0; i < MAX_LIGHTS; i++) {
printf("%d: dist = %g\n", ld.num, ld.brightness);
}
}
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glPushMatrix();
glRotatef(angle, 0.0, 1.0, 0.0);

glDisable(GL_LIGHTING);
for (i = 0; i < MAX_LIGHTS; i++) {
drawLight(&linfo);
}

/* After sorting, the first numActiveLights (ie, <8) light sources are the
light sources with the biggest contribution to the object's lighting.
Assign these "virtual lights of significance" to OpenGL's actual
available light sources. */


glEnable(GL_LIGHTING);
for (i = 0; i < numActiveLights; i++) {
if (lightState) {
int num = ld.num;

glLightfv(GL_LIGHT0 + i, GL_POSITION, linfo[num].xyz);
glLightfv(GL_LIGHT0 + i, GL_DIFFUSE, linfo[num].rgb);
glEnable(GL_LIGHT0 + i);
} else {
glDisable(GL_LIGHT0 + i);
}
}

glPushMatrix();
glTranslatef(x, y, z);
switch (object) {
case M_SPHERE:
glCallList(DL_BIG_SPHERE);
break;
case M_ICO:
glCallList(DL_ICO);
break;
}
glPopMatrix();

if (labelLights) {
glDisable(GL_DEPTH_TEST);
glDisable(GL_LIGHTING);
for (i = 0; i < numActiveLights; i++) {
labelLight(&linfo[ld.num], i);
}
glEnable(GL_DEPTH_TEST);
}
glPopMatrix();

if (timeFrames) {
glFinish();
end = glutGet(GLUT_ELAPSED_TIME);
printf("Speed %.3g frames/sec (%d ms)\n",
1000.0 / (end - start), end - start);
}
if (!singleBuffer) {
glutSwapBuffers();
}
}

void
idle(void)
{
t += 0.005;
glutPostRedisplay();
}

/* When not visible, stop animating. Restart when visible again. */
static void
visible(int vis)
{
if (vis == GLUT_VISIBLE) {
if (animation)
glutIdleFunc(idle);
} else {
if (!animation)
glutIdleFunc(NULL);
}
}

/* Press any key to redraw; good when motion stopped and performance
reporting on. */

/* ARGSUSED */
static void
key(unsigned char c, int x, int y)
{
int i;

switch (c) {
case 27:
exit(0); /* IRIS GLism, Escape quits. */
break;
case ' ':
animation = 1 - animation;
if (animation)
glutIdleFunc(idle);
else
glutIdleFunc(NULL);
break;
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
lightState[c - '0'] = 1 - lightState[c - '0'];
break;
case 13:
for (i = 0; i < numActiveLights; i++) {
lightState = 1;
}
break;
}
glutPostRedisplay();
}

/* ARGSUSED3 */
void
mouse(int button, int state, int x, int y)
{
if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN) {
moving = 1;
begin = x;
}
if (button == GLUT_LEFT_BUTTON && state == GLUT_UP) {
moving = 0;
}
}

/* ARGSUSED1 */
void
motion(int x, int y)
{
if (moving) {
angle = angle + (x - begin);
begin = x;
glutPostRedisplay();
}
}

void
menu(int value)
{
int i;

switch (value) {
case M_SPHERE:
object = M_SPHERE;
break;
case M_ICO:
object = M_ICO;
break;
case M_LABELS:
labelLights = 1 - labelLights;
break;
case M_LINEAR:
case M_QUAD:
attenuation = value;
for (i = 0; i < numActiveLights; i++) {
initLight(i);
}
break;
case M_REPORT_SIG:
reportLightSignificance = 1 - reportLightSignificance;
break;
case M_LAMBERTIAN:
brightnessModel = M_LAMBERTIAN;
glutSetWindowTitle("multilight (Lambertian-based)");
break;
case M_DISTANCE:
brightnessModel = M_DISTANCE;
glutSetWindowTitle("multilight (Distance-based)");
break;
case M_TIME:
timeFrames = 1 - timeFrames;
break;
case 666:
exit(0);
}
glutPostRedisplay();
}

int
main(int argc, char **argv)
{
int i;

glutInitWindowSize(400, 200);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH | GLUT_MULTISAMPLE);
glutInit(&argc, argv);

for (i = 1; i < argc; i++) {
if (!strcmp("-sb", argv)) {
glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_MULTISAMPLE);
singleBuffer = 1;
}
}

glutCreateWindow("multilight");

glClearColor(0.0, 0.0, 0.0, 0.0);

glMatrixMode(GL_PROJECTION);
gluPerspective(50.0, 2.0, 0.1, 100.0);
glMatrixMode(GL_MODELVIEW);
gluLookAt(
0.0, 1.0, -16.0,
0.0, 0.0, 0.0,
0.0, 1.0, 0.);

numActiveLights = MIN_VALUE(MAX_LIGHTS, 8);
for (i = 0; i < numActiveLights; i++) {
initLight(i);
}

glLightModelfv(GL_LIGHT_MODEL_AMBIENT, modelAmb);
glLightModelf(GL_LIGHT_MODEL_LOCAL_VIEWER, GL_TRUE);
glLightModelf(GL_LIGHT_MODEL_TWO_SIDE, GL_FALSE);
glEnable(GL_CULL_FACE);
glEnable(GL_DEPTH_TEST);

glMaterialfv(GL_FRONT, GL_AMBIENT, matAmb);
glMaterialfv(GL_FRONT, GL_DIFFUSE, matDiff);
glMaterialfv(GL_FRONT, GL_SPECULAR, matSpec);
glMaterialfv(GL_FRONT, GL_EMISSION, matEmission);
glMaterialf(GL_FRONT, GL_SHININESS, 10.0);

glNewList(DL_LIGHT_SPHERE, GL_COMPILE);
glutSolidSphere(0.2, 4, 4);
glEndList();

glNewList(DL_BIG_SPHERE, GL_COMPILE);
glutSolidSphere(1.5, 20, 20);
glEndList();

glNewList(DL_ICO, GL_COMPILE);
glutSolidIcosahedron();
glEndList();

glutDisplayFunc(display);
glutVisibilityFunc(visible);
glutKeyboardFunc(key);
glutMouseFunc(mouse);
glutMotionFunc(motion);

glutCreateMenu(menu);
glutAddMenuEntry("Sphere", M_SPHERE);
glutAddMenuEntry("Icosahedron", M_ICO);
glutAddMenuEntry("Linear attenuation", M_LINEAR);
glutAddMenuEntry("Quadratic attenuation", M_QUAD);
glutAddMenuEntry("Toggle Light Number Labels", M_LABELS);
glutAddMenuEntry("Report Light Significance", M_REPORT_SIG);
glutAddMenuEntry("Lambertian-based Significance", M_LAMBERTIAN);
glutAddMenuEntry("Distance-based Significance", M_DISTANCE);
glutAddMenuEntry("Time Frames", M_TIME);
glutAddMenuEntry("Quit", 666);
glutAttachMenu(GLUT_RIGHT_BUTTON);

glutMainLoop();
return 0; /* ANSI C requires main to return int. */
}



HTH

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MARS_999,

Thanks a lot for your timely reply, however, in the code you gave I can't find the statement: glEnable(GLUT_MULTISAMPLE); so I figure the sample doesn't use multisampling, am I right?

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im pretty sure glut hasnt been updated since that multisample became part of the core.
try another lib eg sdl which does do multisample
(also i think the user can override the programs choice with the driver settings)

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Guest Anonymous Poster
Quote:
Original post by xmllmx
MARS_999,

Thanks a lot for your timely reply, however, in the code you gave I can't find the statement: glEnable(GLUT_MULTISAMPLE); so I figure the sample doesn't use multisampling, am I right?


Maybe try glEnable(GL_MULTISAMPLE); instead of glEnable(GLUT_MULTISAMPLE);

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Quote:
Original post by Anonymous Poster
Maybe try glEnable(GL_MULTISAMPLE); instead of glEnable(GLUT_MULTISAMPLE);


I tried as you said, but no effect.

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Quote:
Original post by xmllmx
MARS_999,

Thanks a lot for your timely reply, however, in the code you gave I can't find the statement: glEnable(GLUT_MULTISAMPLE); so I figure the sample doesn't use multisampling, am I right?


Not sure but this code is in there

glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH | GLUT_MULTISAMPLE);

If Mark J. Kilgard wrote it, then it must be correct... But if you can't get FSAA to work with glut move to SDL its easy or use win32 and setup your PFD struct correctly.

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      #include "Brain.h" #include <glm/gtc/matrix_transform.hpp> #include <vector> struct Sprite::Implementation { //Position. struct pos pos; //Tag. std::string tag; //Texture. Texture *texture; //Model matrix. glm::mat4 model; //Vertex Array Object. VertexArray *vao; //Vertex Buffer Object. VertexBuffer *vbo; //Layout. VertexBufferLayout *layout; //Index Buffer Object. IndexBuffer *ibo; //Shader. Shader *program; //Brains. std::vector<Brain *> brains; //Deconstructor. ~Implementation(); }; Sprite::Sprite(std::string image_path, std::string tag, float x, float y) { //Create Pointer To Implementaion. m_Impl = new Implementation(); //Set the Position of the Sprite object. m_Impl->pos.x = x; m_Impl->pos.y = y; //Set the tag. m_Impl->tag = tag; //Create The Texture. m_Impl->texture = new Texture(image_path); //Initialize the model Matrix. m_Impl->model = glm::mat4(1.0f); //Get the Width and the Height of the Texture. int width = m_Impl->texture->GetWidth(); int height = m_Impl->texture->GetHeight(); //Create the Verticies. float verticies[] = { //Positions //Texture Coordinates. x, y, 0.0f, 0.0f, x + width, y, 1.0f, 0.0f, x + width, y + height, 1.0f, 1.0f, x, y + height, 0.0f, 1.0f }; //Create the Indicies. unsigned int indicies[] = { 0, 1, 2, 2, 3, 0 }; //Create Vertex Array. m_Impl->vao = new VertexArray(); //Create the Vertex Buffer. m_Impl->vbo = new VertexBuffer((void *)verticies, sizeof(verticies)); //Create The Layout. m_Impl->layout = new VertexBufferLayout(); m_Impl->layout->PushFloat(2); m_Impl->layout->PushFloat(2); m_Impl->vao->AddBuffer(m_Impl->vbo, m_Impl->layout); //Create the Index Buffer. m_Impl->ibo = new IndexBuffer(indicies, 6); //Create the new shader. m_Impl->program = new Shader("Shaders/SpriteShader.shader"); } //Render. void Sprite::Render(Window * window) { //Create the projection Matrix based on the current window width and height. glm::mat4 proj = glm::ortho(0.0f, (float)window->GetWidth(), 0.0f, (float)window->GetHeight(), -1.0f, 1.0f); //Set the MVP Uniform. m_Impl->program->setUniformMat4f("u_MVP", proj * m_Impl->model); //Run All The Brains (Scripts) of this game object (sprite). for (unsigned int i = 0; i < m_Impl->brains.size(); i++) { //Get Current Brain. Brain *brain = m_Impl->brains[i]; //Call the start function only once! if (brain->GetStart()) { brain->SetStart(false); brain->Start(); } //Call the update function every frame. brain->Update(); } //Render. window->GetRenderer()->Draw(m_Impl->vao, m_Impl->ibo, m_Impl->texture, m_Impl->program); } void Sprite::Move(float speed, bool left, bool right, bool up, bool down) { if (left) { m_Impl->pos.x -= speed; m_Impl->model = glm::translate(m_Impl->model, glm::vec3(-speed, 0, 0)); } if (right) { m_Impl->pos.x += speed; m_Impl->model = glm::translate(m_Impl->model, glm::vec3(speed, 0, 0)); } if (up) { m_Impl->pos.y += speed; m_Impl->model = glm::translate(m_Impl->model, glm::vec3(0, speed, 0)); } if (down) { m_Impl->pos.y -= speed; m_Impl->model = glm::translate(m_Impl->model, glm::vec3(0, -speed, 0)); } } void Sprite::AddBrain(Brain * brain) { //Push back the brain object. m_Impl->brains.push_back(brain); } pos *Sprite::GetPos() { return &m_Impl->pos; } std::string Sprite::GetTag() { return m_Impl->tag; } int Sprite::GetWidth() { return m_Impl->texture->GetWidth(); } int Sprite::GetHeight() { return m_Impl->texture->GetHeight(); } Sprite::~Sprite() { delete m_Impl; } //Implementation Deconstructor. Sprite::Implementation::~Implementation() { delete texture; delete vao; delete vbo; delete layout; delete ibo; delete program; }  
      Renderer Class
      #include "Renderer.h" #include "Error.h" Renderer::Renderer() { } Renderer::~Renderer() { } void Renderer::Draw(VertexArray * vao, IndexBuffer * ibo, Texture *texture, Shader * program) { vao->Bind(); ibo->Bind(); program->Bind(); if (texture != NULL) texture->Bind(); GLCall(glDrawElements(GL_TRIANGLES, ibo->GetCount(), GL_UNSIGNED_INT, NULL)); } void Renderer::Clear(float r, float g, float b) { GLCall(glClearColor(r, g, b, 1.0)); GLCall(glClear(GL_COLOR_BUFFER_BIT)); } void Renderer::Update(GLFWwindow *window) { /* Swap front and back buffers */ glfwSwapBuffers(window); /* Poll for and process events */ glfwPollEvents(); }  
      Shader Code
      #shader vertex #version 330 core layout(location = 0) in vec4 aPos; layout(location = 1) in vec2 aTexCoord; out vec2 t_TexCoord; uniform mat4 u_MVP; void main() { gl_Position = u_MVP * aPos; t_TexCoord = aTexCoord; } #shader fragment #version 330 core out vec4 aColor; in vec2 t_TexCoord; uniform sampler2D u_Texture; void main() { aColor = texture(u_Texture, t_TexCoord); } Also i'm pretty sure that every time i'm hitting the up, down, left and right arrows on the keyboard, i'm changing the model Matrix of the Player and not the others.
       
      Window Class:
      #include "Window.h" #include <GL/glew.h> #include <GLFW/glfw3.h> #include "Error.h" #include "Renderer.h" #include "Scene.h" #include "Input.h" //Global Variables. int screen_width, screen_height; //On Window Resize. void OnWindowResize(GLFWwindow *window, int width, int height); //Implementation Structure. struct Window::Implementation { //GLFW Window. GLFWwindow *GLFW_window; //Renderer. Renderer *renderer; //Delta Time. double delta_time; //Frames Per Second. int fps; //Scene. Scene *scnene; //Input. Input *input; //Deconstructor. ~Implementation(); }; //Window Constructor. Window::Window(std::string title, int width, int height) { //Initializing width and height. screen_width = width; screen_height = height; //Create Pointer To Implementation. m_Impl = new Implementation(); //Try initializing GLFW. if (!glfwInit()) { std::cout << "GLFW could not be initialized!" << std::endl; std::cout << "Press ENTER to exit..." << std::endl; std::cin.get(); exit(-1); } //Setting up OpenGL Version 3.3 Core Profile. glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3); glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); /* Create a windowed mode window and its OpenGL context */ m_Impl->GLFW_window = glfwCreateWindow(width, height, title.c_str(), NULL, NULL); if (!m_Impl->GLFW_window) { std::cout << "GLFW could not create a window!" << std::endl; std::cout << "Press ENTER to exit..." << std::endl; std::cin.get(); glfwTerminate(); exit(-1); } /* Make the window's context current */ glfwMakeContextCurrent(m_Impl->GLFW_window); //Initialize GLEW. if(glewInit() != GLEW_OK) { std::cout << "GLEW could not be initialized!" << std::endl; std::cout << "Press ENTER to exit..." << std::endl; std::cin.get(); glfwTerminate(); exit(-1); } //Enabling Blending. GLCall(glEnable(GL_BLEND)); GLCall(glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)); //Setting the ViewPort. GLCall(glViewport(0, 0, width, height)); //**********Initializing Implementation**********// m_Impl->renderer = new Renderer(); m_Impl->delta_time = 0.0; m_Impl->fps = 0; m_Impl->input = new Input(this); //**********Initializing Implementation**********// //Set Frame Buffer Size Callback. glfwSetFramebufferSizeCallback(m_Impl->GLFW_window, OnWindowResize); } //Window Deconstructor. Window::~Window() { delete m_Impl; } //Window Main Loop. void Window::MainLoop() { //Time Variables. double start_time = 0, end_time = 0, old_time = 0, total_time = 0; //Frames Counter. int frames = 0; /* Loop until the user closes the window */ while (!glfwWindowShouldClose(m_Impl->GLFW_window)) { old_time = start_time; //Total time of previous frame. start_time = glfwGetTime(); //Current frame start time. //Calculate the Delta Time. m_Impl->delta_time = start_time - old_time; //Get Frames Per Second. if (total_time >= 1) { m_Impl->fps = frames; total_time = 0; frames = 0; } //Clearing The Screen. m_Impl->renderer->Clear(0, 0, 0); //Render The Scene. if (m_Impl->scnene != NULL) m_Impl->scnene->Render(this); //Updating the Screen. m_Impl->renderer->Update(m_Impl->GLFW_window); //Increasing frames counter. frames++; //End Time. end_time = glfwGetTime(); //Total time after the frame completed. total_time += end_time - start_time; } //Terminate GLFW. glfwTerminate(); } //Load Scene. void Window::LoadScene(Scene * scene) { //Set the scene. m_Impl->scnene = scene; } //Get Delta Time. double Window::GetDeltaTime() { return m_Impl->delta_time; } //Get FPS. int Window::GetFPS() { return m_Impl->fps; } //Get Width. int Window::GetWidth() { return screen_width; } //Get Height. int Window::GetHeight() { return screen_height; } //Get Input. Input * Window::GetInput() { return m_Impl->input; } Renderer * Window::GetRenderer() { return m_Impl->renderer; } GLFWwindow * Window::GetGLFWindow() { return m_Impl->GLFW_window; } //Implementation Deconstructor. Window::Implementation::~Implementation() { delete renderer; delete input; } //OnWindowResize void OnWindowResize(GLFWwindow *window, int width, int height) { screen_width = width; screen_height = height; //Updating the ViewPort. GLCall(glViewport(0, 0, width, height)); }  
      Brain Class
      #include "Brain.h" #include "Sprite.h" #include "Window.h" struct Brain::Implementation { //Just A Flag. bool started; //Window Pointer. Window *window; //Sprite Pointer. Sprite *sprite; }; Brain::Brain(Window *window, Sprite *sprite) { //Create Pointer To Implementation. m_Impl = new Implementation(); //Initialize Implementation. m_Impl->started = true; m_Impl->window = window; m_Impl->sprite = sprite; } Brain::~Brain() { //Delete Pointer To Implementation. delete m_Impl; } void Brain::Start() { } void Brain::Update() { } Window * Brain::GetWindow() { return m_Impl->window; } Sprite * Brain::GetSprite() { return m_Impl->sprite; } bool Brain::GetStart() { return m_Impl->started; } void Brain::SetStart(bool value) { m_Impl->started = value; } Script Class (Its a Brain Subclass!!!)
      #include "Script.h" Script::Script(Window *window, Sprite *sprite) : Brain(window, sprite) { } Script::~Script() { } void Script::Start() { std::cout << "Game Started!" << std::endl; } void Script::Update() { Input *input = this->GetWindow()->GetInput(); Sprite *sp = this->GetSprite(); //Move this sprite. this->GetSprite()->Move(200 * this->GetWindow()->GetDeltaTime(), input->GetKeyDown("left"), input->GetKeyDown("right"), input->GetKeyDown("up"), input->GetKeyDown("down")); std::cout << sp->GetTag().c_str() << ".x = " << sp->GetPos()->x << ", " << sp->GetTag().c_str() << ".y = " << sp->GetPos()->y << std::endl; }  
      Main:
      #include "SpaceShooterEngine.h" #include "Script.h" int main() { Window w("title", 600,600); Scene *scene = new Scene(); Sprite *player = new Sprite("Resources/Images/player.png", "Player", 100,100); Sprite *other = new Sprite("Resources/Images/cherno.png", "Other", 400, 100); Sprite *other2 = new Sprite("Resources/Images/cherno.png", "Other", 300, 400); Brain *brain = new Script(&w, player); player->AddBrain(brain); scene->AddSprite(player); scene->AddSprite(other); scene->AddSprite(other2); w.LoadScene(scene); w.MainLoop(); return 0; }  
       
      I literally can't find what is wrong. If you need more code, ask me to post it. I will also attach all the source files.
      Brain.cpp
      Error.cpp
      IndexBuffer.cpp
      Input.cpp
      Renderer.cpp
      Scene.cpp
      Shader.cpp
      Sprite.cpp
      Texture.cpp
      VertexArray.cpp
      VertexBuffer.cpp
      VertexBufferLayout.cpp
      Window.cpp
      Brain.h
      Error.h
      IndexBuffer.h
      Input.h
      Renderer.h
      Scene.h
      Shader.h
      SpaceShooterEngine.h
      Sprite.h
      Texture.h
      VertexArray.h
      VertexBuffer.h
      VertexBufferLayout.h
      Window.h
    • By Cristian Decu
      Hello fellow programmers,
      For a couple of days now i've decided to build my own planet renderer just to see how floating point precision issues
      can be tackled. As you probably imagine, i've quickly faced FPP issues when trying to render absurdly large planets.
       
      I have used the classical quadtree LOD approach;
      I've generated my grids with 33 vertices, (x: -1 to 1, y: -1 to 1, z = 0).
      Each grid is managed by a TerrainNode class that, depending on the side it represents (top, bottom, left right, front, back),
      creates a special rotation-translation matrix that moves and rotates the grid away from the origin so that when i finally
      normalize all the vertices on my vertex shader i can get a perfect sphere.
      T = glm::translate(glm::dmat4(1.0), glm::dvec3(0.0, 0.0, 1.0)); R = glm::rotate(glm::dmat4(1.0), glm::radians(180.0), glm::dvec3(1.0, 0.0, 0.0)); sides[0] = new TerrainNode(1.0, radius, T * R, glm::dvec2(0.0, 0.0), new TerrainTile(1.0, SIDE_FRONT)); T = glm::translate(glm::dmat4(1.0), glm::dvec3(0.0, 0.0, -1.0)); R = glm::rotate(glm::dmat4(1.0), glm::radians(0.0), glm::dvec3(1.0, 0.0, 0.0)); sides[1] = new TerrainNode(1.0, radius, R * T, glm::dvec2(0.0, 0.0), new TerrainTile(1.0, SIDE_BACK)); // So on and so forth for the rest of the sides As you can see, for the front side grid, i rotate it 180 degrees to make it face the camera and push it towards the eye;
      the back side is handled almost the same way only that i don't need to rotate it but simply push it away from the eye.
      The same technique is applied for the rest of the faces (obviously, with the proper rotations / translations).
      The matrix that result from the multiplication of R and T (in that particular order) is send to my vertex shader as `r_Grid'.
      // spherify vec3 V = normalize((r_Grid * vec4(r_Vertex, 1.0)).xyz); gl_Position = r_ModelViewProjection * vec4(V, 1.0); The `r_ModelViewProjection' matrix is generated on the CPU in this manner.
      // No the most efficient way, but it works. glm::dmat4 Camera::getMatrix() { // Create the view matrix // Roll, Yaw and Pitch are all quaternions. glm::dmat4 View = glm::toMat4(Roll) * glm::toMat4(Pitch) * glm::toMat4(Yaw); // The model matrix is generated by translating in the oposite direction of the camera. glm::dmat4 Model = glm::translate(glm::dmat4(1.0), -Position); // Projection = glm::perspective(fovY, aspect, zNear, zFar); // zNear = 0.1, zFar = 1.0995116e12 return Projection * View * Model; } I managed to get rid of z-fighting by using a technique called Logarithmic Depth Buffer described in this article; it works amazingly well, no z-fighting at all, at least not visible.
      Each frame i'm rendering each node by sending the generated matrices this way.
      // set the r_ModelViewProjection uniform // Sneak in the mRadiusMatrix which is a matrix that contains the radius of my planet. Shader::setUniform(0, Camera::getInstance()->getMatrix() * mRadiusMatrix); // set the r_Grid matrix uniform i created earlier. Shader::setUniform(1, r_Grid); grid->render(); My planet's radius is around 6400000.0 units, absurdly large, but that's what i really want to achieve;
      Everything works well, the node's split and merge as you'd expect, however whenever i get close to the surface
      of the planet the rounding errors start to kick in giving me that lovely stairs effect.
      I've read that if i could render each grid relative to the camera i could get better precision on the surface, effectively
      getting rid of those rounding errors.
       
      My question is how can i achieve this relative to camera rendering in my scenario here?
      I know that i have to do most of the work on the CPU with double, and that's exactly what i'm doing.
      I only use double on the CPU side where i also do most of the matrix multiplications.
      As you can see from my vertex shader i only do the usual r_ModelViewProjection * (some vertex coords).
       
      Thank you for your suggestions!
       
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