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cifa

OpenGL [Very noobish] Cube not render

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Hi there, first I want to point out that I'm a huge begginer in OpenGL actually I've started today, but I've done a bit in WebGL.
Trying to port, from WebGL a simple program that show a cube and this is the result:

(I know that it may seem a strange way to do this, but I need a port that have to look like my WebGL sample) 

 

// Include standard headers
#include <stdio.h>
#include <stdlib.h>
#include <stack>
#include <iostream>


// Include GLEW
#include <GL/glew.h>

// Include GLFW
#include <GL/glfw.h>

// Include GLM
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
using namespace glm;

#include <common/shader.hpp>

int viewportWidth=1024;
int viewporthHeight=768;


int initWindow(char * nome);
void drawScene();
void initBuffers();
void cleanBuffers();
void initShaders();
void mvMatrixPush();
void mvMatrixPop();
void printMat(glm::mat4  mat);
void setMatrixUniform();

struct programField {
	GLint vertexPositionAttribute;
	GLint vertexColorAttribute;
	GLint pMatrixUniform;
	GLint mvMatrixUniform;
	
};

struct bufferField{
	int itemSize;
	int numItems;
};

struct programField program;

GLuint programID;
GLuint VertexArrayID;
GLuint vertexbuffer;

int main( void )
{
	initWindow("Prova");
	initShaders();
	initBuffers();
	do{	
		drawScene();
	} // Check if the ESC key was pressed or the window was closed
	while( glfwGetKey( GLFW_KEY_ESC ) != GLFW_PRESS &&
		   glfwGetWindowParam( GLFW_OPENED ) );
	// Close OpenGL window and terminate GLFW
	glfwTerminate();

	return 0;
}

void initShaders(){
	programID = LoadShaders( "vs.vertexshader", "fs.fragmentshader" );
	glUseProgram(programID);	
	program.vertexPositionAttribute=glGetAttribLocation(programID, "aVertexPosition");
	glEnableVertexAttribArray(program.vertexPositionAttribute);
	program.vertexColorAttribute=glGetAttribLocation(programID, "aVertexColor");
	glEnableVertexAttribArray(program.vertexColorAttribute);
	program.pMatrixUniform=glGetUniformLocation(programID, "uPMatrix");
	program.mvMatrixUniform=glGetUniformLocation(programID, "uMVMatrix");
}

glm::mat4 mvMatrix = glm::mat4(1.0);
glm::mat4 pMatrix = glm::mat4(1.0);
std::stack<glm::mat4> mvMatrixStack;      

void mvMatrixPush(){
	glm::mat4 copy = glm::mat4(1.0);
	copy = mvMatrix;
	mvMatrixStack.push(copy);
}

void mvMatrixPop(){
	if(mvMatrixStack.size()==0){
		printf("Invalid pop");
		return;
	}
	mvMatrix=mvMatrixStack.top();
	mvMatrixStack.pop();
}

void setMatrixUniform(){
	glUniformMatrix4fv(program.pMatrixUniform, 1, GL_FALSE, &pMatrix[0][0]);
	glUniformMatrix4fv(program.mvMatrixUniform, 1, GL_FALSE, &mvMatrix[0][0]);
}

float degToRad(int degrees){
	return degrees*3.14f/180;
}


GLuint vertexPositionBuffer;
struct bufferField vertexPositionField;
GLuint vertexColorBuffer;
struct bufferField vertexColorField;
GLuint vertexIndexBuffer;
struct bufferField vertexIndicesField;

void initBuffers(){

	glGenBuffers(1, &vertexPositionBuffer);
	glBindBuffer(GL_ARRAY_BUFFER, vertexPositionBuffer);

	static const GLfloat vertices[] = { 
//Faccia frontale
	-1.0f,-1.0f,1.0f,
	1.0f,-1.0f,1.0f,
	1.0f,1.0f,1.0f,
	-1.0f,1.0f,1.0f,

	//Faccia retro
	-1.0f,-1.0f,-1.0f,
	-1.0f,1.0f,-1.0f,
	1.0f,1.0f,-1.0f,
	1.0f,-1.0f,-1.0f,

	//Faccia in cima
	-1.0f,1.0f,-1.0f,
	-1.0f,1.0f,1.0f,
	1.0f,2.0f,1.0f,
	1.0f,1.0f,-1.0f,

	//Faccia sotto
    -1.0f, -1.0f, -1.0f,
    1.0f, -1.0f, -1.0f,
    1.0f, -1.0f,  1.0f,
    -1.0f, -1.0f,  1.0f,

    //Faccia destra
    1.0f, -1.0f, -1.0f,
    1.0f,  1.0f, -1.0f,
    1.0f,  1.0f,  1.0f,
    1.0f, -1.0f,  1.0f,

    //Faccia sinistra
	-1.0f, -1.0f, -1.0f,
    -1.0f, -1.0f,  1.0f,
    -1.0f,  1.0f,  1.0f,
    -1.0f,  1.0f, -1.0f

	};


	
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
	vertexPositionField.itemSize=3;
	vertexPositionField.numItems=24;

	
	glGenBuffers(1, &vertexColorBuffer);
	glBindBuffer(GL_ARRAY_BUFFER, vertexColorBuffer);

	static const GLfloat colors[]={
	
	//Faccia frontale
	1.0f,0.0f,0.0f,1.0f,
	1.0f,0.0f,0.0f,1.0f,
	1.0f,0.0f,0.0f,1.0f,
	1.0f,0.0f,0.0f,1.0f,

	//Retro
	0.0f,1.0f,0.0f,1.0f,
	0.0f,1.0f,0.0f,1.0f,
	0.0f,1.0f,0.0f,1.0f,
	0.0f,1.0f,0.0f,1.0f,

	//In cima
	0.0f,0.0f,1.0f,1.0f,
	0.0f,0.0f,1.0f,1.0f,
	0.0f,0.0f,1.0f,1.0f,
	0.0f,0.0f,1.0f,1.0f,

	//Faccia sotto
	1.0f,1.0f,0.0f,1.0f,
	1.0f,1.0f,0.0f,1.0f,
	1.0f,1.0f,0.0f,1.0f,
	1.0f,1.0f,0.0f,1.0f,

	//Faccia destra
	0.0f,1.0f,1.0f,1.0f,
	0.0f,1.0f,1.0f,1.0f,
	0.0f,1.0f,1.0f,1.0f,
	0.0f,1.0f,1.0f,1.0f,

	//Faccio sinistra
	1.0f,0.0f,1.0f,1.0f,
	1.0f,0.0f,1.0f,1.0f,
	1.0f,0.0f,1.0f,1.0f,
	1.0f,0.0f,1.0f,1.0f
	};

	glBufferData(GL_ARRAY_BUFFER, sizeof(colors), colors, GL_STATIC_DRAW);
	vertexColorField.itemSize=4;
	vertexColorField.numItems=24;

	glGenBuffers(1, &vertexIndexBuffer);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vertexIndexBuffer);

	static const GLint indices[]={
	0,1,2,	0,2,3,
	4,5,6,	4,6,7,
	8,9,10,	8,10,11,
	12,13,14,	12,14,15,
	16,17,18,	16,18,19,
	20,21,22,	20,22,23
	};

	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
	vertexIndicesField.itemSize=1;
	vertexIndicesField.numItems=36;
}



void drawScene(){

		// Clear the screen
		glClear( GL_COLOR_BUFFER_BIT);
		pMatrix=glm::perspective(45.0f, float(viewportWidth/viewporthHeight), 0.1f, 100.0f);

		mvMatrix = glm::mat4(1.0);
		mvMatrix=glm::translate(mvMatrix, glm::vec3(-1.5f,0.0f,-8.0f));

		mvMatrixPush();

		glBindBuffer(GL_ARRAY_BUFFER, vertexPositionBuffer);
		glVertexAttribPointer(
			program.vertexPositionAttribute,                 
			vertexPositionField.itemSize,                  // size
			GL_FLOAT,           // type
			GL_FALSE,           // normalized?
			0,                  // stride
			(void*)0            // array buffer offset
		);

		
		glBindBuffer(GL_ARRAY_BUFFER, vertexColorBuffer);
		glVertexAttribPointer(
			program.vertexColorAttribute,                 
			vertexColorField.itemSize,                  // size
			GL_FLOAT,           // type
			GL_FALSE,           // normalized?
			0,                  // stride
			(void*)0            // array buffer offset
		);


		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vertexIndexBuffer);
		setMatrixUniform();
		glDrawElements(GL_TRIANGLES,vertexIndicesField.numItems, GL_UNSIGNED_SHORT, 0);


		// Swap buffers
		glfwSwapBuffers();

}

int initWindow(char * nome){
	// Initialise GLFW
	if( !glfwInit() )
	{
		fprintf( stderr, "Failed to initialize GLFW\n" );
		return -1;
	}

	glfwOpenWindowHint(GLFW_FSAA_SAMPLES, 4);
	glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 3);
	glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, 3);
	glfwOpenWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

	// Open a window and create its OpenGL context
	if( !glfwOpenWindow( viewportWidth, viewporthHeight, 0,0,0,0, 32,0, GLFW_WINDOW ) )
	{
		fprintf( stderr, "Failed to open GLFW window. If you have an Intel GPU, they are not 3.3 compatible. Try the 2.1 version of the tutorials.\n" );
		glfwTerminate();
		return -1;
	}

	glfwSetWindowTitle(nome );

	// Ensure we can capture the escape key being pressed below
	glfwEnable( GLFW_STICKY_KEYS );

	// Dark blue background
	glClearColor(0.9f, 0.9f, 0.9f, 0.0f);

	glEnable(GL_DEPTH_TEST);

		// Initialize GLEW
	glewExperimental = true; // Needed for core profile
	if (glewInit() != GLEW_OK) {
		fprintf(stderr, "Failed to initialize GLEW\n");
		return -1;
	}

	return 0;
}

 

With shaders that are:

 

#version 330 core
	attribute vec3 aVertexPosition;
	attribute vec4 aVertexColor;

	uniform mat4 uMVMatrix;
	uniform mat4 uPMatrix;

	varying vec4 vColor;

	void main(void){
		gl_Position=uPMatrix*uMVMatrix*vec4(aVertexPosition, 1.0);
		vColor=aVertexColor;

	}

#version 330 core

	precision mediump float;

	varying vec4 vColor;

	void main(void){
		gl_FragColor=vColor;
	}

 

 

 

(Sorry for the indenting, bad copy-paste) 

 

 
 

It compiles, but no cube is showed,it is surely a banal issue but I don't know how to find it out. 

Sorry for the probably stupid question and if my English is bad smile.png 

Thanks a lot!

 

Edited by cifa

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That's a lot of code to read through. You should probably try to start with just a camera and a basic shape (without any shaders or buffers or whatever) and expand from there step by step. Running such complex code as yours usually never works at the first time.

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That's a lot of code to read through. You should probably try to start with just a camera and a basic shape (without any shaders or buffers or whatever) and expand from there step by step. Running such complex code as yours usually never works at the first time.

 

Thanks for the reply first of all.

Secondly, I've ""learned"" the basic GL concept with WebGL, what I need (for many reason that are boring to explain) is a 1:1 port of my WebGL code to OpenGL. 

Oh and that code on WebGL (with a basic port to javascript) works pretty well

Edited by cifa

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You've enabled depth testing but you appear to only be clearing the colour buffer and not the depth buffer. It's possible that your first frame is rendering successfully but then each successive frame is failing because the depth test is failing.

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One thing I noticed is that you're defining the indices as int, but you're using them as unsigned short.

 

static const GLint indices[] = { ... };
glDrawElements(GL_TRIANGLES,vertexIndicesField.numItems, GL_UNSIGNED_SHORT, 0); 

I would probably use GLuint indices[] and GL_UNSIGNED_INT for glDrawElements.

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Thank you all for the replies

 

 

You've enabled depth testing but you appear to only be clearing the colour buffer and not the depth buffer. It's possible that your first frame is rendering successfully but then each successive frame is failing because the depth test is failing.

 

Uh I copy-pasted the wrong version I guess, because I clear it on my source. Probably it was a desperate test.

Even with clearing GL:DEPTH_BUFFER_BIT nothing changes. 

 

 

One thing I noticed is that you're defining the indices as int, but you're using them as unsigned short.

 

static const GLint indices[] = { ... };
glDrawElements(GL_TRIANGLES,vertexIndicesField.numItems, GL_UNSIGNED_SHORT, 0); 

I would probably use GLuint indices[] and GL_UNSIGNED_INT for glDrawElements.

 

 

Thanks I didn't see it, but even with that fix it still doesn't work. 

It doesn't work also with drawArrays.

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You don't seem to call mvMatrixPop, but it doesn't probably matter that much though. Also, I'm not sure if GLSL 3.3 core likes keywords "attribute" and "varying" because those are deprecated, use "in" and "out" instead. You should also use glGetProgram and glGetProgramInfoLog for grabbing some information about the shader program.

 

You could also try running the application in gDebugger, it's an awesome program for debugging OpenGL applications.

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You don't seem to call mvMatrixPop, but it doesn't probably matter that much though. Also, I'm not sure if GLSL 3.3 core likes keywords "attribute" and "varying" because those are deprecated, use "in" and "out" instead. You should also use glGetProgram and glGetProgramInfoLog for grabbing some information about the shader program.

 

You could also try running the application in gDebugger, it's an awesome program for debugging OpenGL applications.

 

Thanks! No I used mvMatrixPop in a more complex example, that after those problem I've shrinked to this one. 

 glGetProgramInfoLog is called inside 

 

LoadShaders( "vs.vertexshader", "fs.fragmentshader" );

 

that I haven't post it here because found on online tutorial. And everything (compiling and linking) it's fine with shaders

 

 

I also used gDebugger but I haven't found out the problem :(

Edited by cifa

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Gah, I'm not so familiar with these core profiles and stuff, but I think I found your problem: http://www.gamedev.net/topic/609951-glvertexattribpointer-giving-gl-invalid-operation/
 
As V-Man says there, "If you are using core profile on GL 3.2, then you must use VAO when you call glBindBuffer and glVertexAttribPointer."
 
I found my way to that thread by starting up gDebugger and turned on breakpoints on errors, then noticed an invalid operation on glVertexAttribPointer, and googled for "glVertexAttribPointer invalid operation"
 
Maybe try with these hints and you should at least see something:
glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 3);
glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, 0);
//glfwOpenWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

And btw, in c++, int/int = int, so your aspect ratio is wrong, float(viewportWidth)/viewporthHeight would work better.

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Gah, I'm not so familiar with these core profiles and stuff, but I think I found your problem: http://www.gamedev.net/topic/609951-glvertexattribpointer-giving-gl-invalid-operation/
 
As V-Man says there, "If you are using core profile on GL 3.2, then you must use VAO when you call glBindBuffer and glVertexAttribPointer."
 
I found my way to that thread by starting up gDebugger and turned on breakpoints on errors, then noticed an invalid operation on glVertexAttribPointer, and googled for "glVertexAttribPointer invalid operation"
 
Maybe try with these hints and you should at least see something:
glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 3);
glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, 0);
//glfwOpenWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

And btw, in c++, int/int = int, so your aspect ratio is wrong, float(viewportWidth)/viewporthHeight would work better.

 

Oh! With those hints it works fine, I'm going to study those core profile-stuff biggrin.png

Thank you so much!

Edited by cifa

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      I'm trying to learn OpenGL through a website and have proceeded until this page of it. The output is a simple triangle. The problem is the complexity.
      I have read that page several times and tried to analyse the code but I haven't understood the code properly and completely yet. This is the code:
       
      #include <glad/glad.h> #include <GLFW/glfw3.h> #include <C:\Users\Abbasi\Desktop\std_lib_facilities_4.h> using namespace std; //****************************************************************************** void framebuffer_size_callback(GLFWwindow* window, int width, int height); void processInput(GLFWwindow *window); // settings const unsigned int SCR_WIDTH = 800; const unsigned int SCR_HEIGHT = 600; const char *vertexShaderSource = "#version 330 core\n" "layout (location = 0) in vec3 aPos;\n" "void main()\n" "{\n" " gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n" "}\0"; const char *fragmentShaderSource = "#version 330 core\n" "out vec4 FragColor;\n" "void main()\n" "{\n" " FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n" "}\n\0"; //******************************* int main() { // glfw: initialize and configure // ------------------------------ glfwInit(); glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3); glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); // glfw window creation GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "My First Triangle", nullptr, nullptr); if (window == nullptr) { cout << "Failed to create GLFW window" << endl; glfwTerminate(); return -1; } glfwMakeContextCurrent(window); glfwSetFramebufferSizeCallback(window, framebuffer_size_callback); // glad: load all OpenGL function pointers if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) { cout << "Failed to initialize GLAD" << endl; return -1; } // build and compile our shader program // vertex shader int vertexShader = glCreateShader(GL_VERTEX_SHADER); glShaderSource(vertexShader, 1, &vertexShaderSource, nullptr); glCompileShader(vertexShader); // check for shader compile errors int success; char infoLog[512]; glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success); if (!success) { glGetShaderInfoLog(vertexShader, 512, nullptr, infoLog); cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << endl; } // fragment shader int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER); glShaderSource(fragmentShader, 1, &fragmentShaderSource, nullptr); glCompileShader(fragmentShader); // check for shader compile errors glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success); if (!success) { glGetShaderInfoLog(fragmentShader, 512, nullptr, infoLog); cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << endl; } // link shaders int shaderProgram = glCreateProgram(); glAttachShader(shaderProgram, vertexShader); glAttachShader(shaderProgram, fragmentShader); glLinkProgram(shaderProgram); // check for linking errors glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success); if (!success) { glGetProgramInfoLog(shaderProgram, 512, nullptr, infoLog); cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << endl; } glDeleteShader(vertexShader); glDeleteShader(fragmentShader); // set up vertex data (and buffer(s)) and configure vertex attributes float vertices[] = { -0.5f, -0.5f, 0.0f, // left 0.5f, -0.5f, 0.0f, // right 0.0f, 0.5f, 0.0f // top }; unsigned int VBO, VAO; glGenVertexArrays(1, &VAO); glGenBuffers(1, &VBO); // bind the Vertex Array Object first, then bind and set vertex buffer(s), //and then configure vertex attributes(s). glBindVertexArray(VAO); glBindBuffer(GL_ARRAY_BUFFER, VBO); glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW); glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0); glEnableVertexAttribArray(0); // note that this is allowed, the call to glVertexAttribPointer registered VBO // as the vertex attribute's bound vertex buffer object so afterwards we can safely unbind glBindBuffer(GL_ARRAY_BUFFER, 0); // You can unbind the VAO afterwards so other VAO calls won't accidentally // modify this VAO, but this rarely happens. Modifying other // VAOs requires a call to glBindVertexArray anyways so we generally don't unbind // VAOs (nor VBOs) when it's not directly necessary. glBindVertexArray(0); // uncomment this call to draw in wireframe polygons. //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE); // render loop while (!glfwWindowShouldClose(window)) { // input // ----- processInput(window); // render // ------ glClearColor(0.2f, 0.3f, 0.3f, 1.0f); glClear(GL_COLOR_BUFFER_BIT); // draw our first triangle glUseProgram(shaderProgram); glBindVertexArray(VAO); // seeing as we only have a single VAO there's no need to // bind it every time, but we'll do so to keep things a bit more organized glDrawArrays(GL_TRIANGLES, 0, 3); // glBindVertexArray(0); // no need to unbind it every time // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.) glfwSwapBuffers(window); glfwPollEvents(); } // optional: de-allocate all resources once they've outlived their purpose: glDeleteVertexArrays(1, &VAO); glDeleteBuffers(1, &VBO); // glfw: terminate, clearing all previously allocated GLFW resources. glfwTerminate(); return 0; } //************************************************** // process all input: query GLFW whether relevant keys are pressed/released // this frame and react accordingly void processInput(GLFWwindow *window) { if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) glfwSetWindowShouldClose(window, true); } //******************************************************************** // glfw: whenever the window size changed (by OS or user resize) this callback function executes void framebuffer_size_callback(GLFWwindow* window, int width, int height) { // make sure the viewport matches the new window dimensions; note that width and // height will be significantly larger than specified on retina displays. glViewport(0, 0, width, height); } As you see, about 200 lines of complicated code only for a simple triangle. 
      I don't know what parts are necessary for that output. And also, what the correct order of instructions for such an output or programs is, generally. That start point is too complex for a beginner of OpenGL like me and I don't know how to make the issue solved. What are your ideas please? What is the way to figure both the code and the whole program out correctly please?
      I wish I'd read a reference that would teach me OpenGL through a step-by-step method. 
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