Exemple

Afin que vous ayez une idée claire de ce à quoi ressemble un code minimal OpenGL 3 qui affiche un triangle coloré, voici l'exemple du triangle coloré version GL 3+ ! Pas la peine de lire dans le détail à nouveau, vous aurez les TPs pour vous y faire x)

const char* vertexShaderSource =
    "#version 330\n"
    "layout(location = 0) in vec3 iVertexPosition;"
    "layout(location = 1) in vec3 iVertexColor;"
    "out vec3 FragColor;"
    "void main() {"
        "FragColor = iVertexColor;"
        "gl_Position = vec4(iVertexPosition, 1.f);"
    "}";

const char* fragmentShaderSource =
    "#version 330\n"
    "in vec3 FragColor;"
    "out vec4 oFragColor;"
    "void main() {"
        "oFragColor = vec4(FragColor, 1.f);"
    "}";

int main() {
    SDL_Init(SDL_INIT_VIDEO);
    
    SDL_SetVideoMode(800, 600, 32, SDL_OPENGL);
    
    GLint error;
    if(GLEW_OK != (error = glewInit())) {
        std::cerr << "Impossible d'initialiser Glew" << std::endl;
        return 1;
    }

    GLuint vbo, vao;
    
    glGenBuffers(1, &vbo);

    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    
        GLfloat vertices[] = {
            -0.5, -0.5,/* Position */ 1., 0., 0., /* Couleur */ // Premier vertex
            0.5, -0.5,/* Position */ 0., 1., 0., /* Couleur */ // Deuxième vertex
            0., 0.5,/* Position */ 0., 0., 1. /* Couleur */ // Troisème vertex
        };
        
        glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
    
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    
    glGenVertexArrays(1, &vao);
    
    glBindVertexArray(vao);
    
        glBindBuffer(GL_ARRAY_BUFFER, vbo);
        
        glEnableVertexAttribArray(0);
        glVertexAttribPointer(
            0, 
            2, 
            GL_FLOAT, 
            GL_FALSE, 
            5 * sizeof(GLfloat), 
            0);
        
        glEnableVertexAttribArray(1);
        glVertexAttribPointer(
            1, 
            3, 
            GL_FLOAT, 
            GL_FALSE, 
            5 * sizeof(GLfloat), 
            (void*) (2 * sizeof(GLfloat)));
        
        glBindBuffer(GL_ARRAY_BUFFER, 0);
    
    glBindVertexArray(0);

    GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
    
    glShaderSource(vertexShader, 1, &vertexShaderSource, 0);
    
    glCompileShader(vertexShader);
    
    GLint compileStatus;
    
    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &compileStatus);
    if(compileStatus == GL_FALSE) {
        GLint logLength;
        glGetShaderiv(vertexShader, GL_INFO_LOG_LENGTH, &logLength);
        
        char* log = new char[logLength];
        
        glGetShaderInfoLog(vertexShader, logLength, 0, log);
        std::cerr << "Vertex Shader error:" << log << std::endl;
        std::cerr << vertexShaderSource << std::endl;
        
        delete [] log;
        return 2;
    }
    
    GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, 0);
    
    glCompileShader(fragmentShader);
    
    glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &compileStatus);
    if(compileStatus == GL_FALSE) {
        GLint logLength;
        glGetShaderiv(fragmentShader, GL_INFO_LOG_LENGTH, &logLength);
        
        char* log = new char[logLength];
        
        glGetShaderInfoLog(fragmentShader, logLength, 0, log);
        std::cerr << "Fragment Shader error:" << log << std::endl;
        std::cerr << fragmentShaderSource << std::endl;
        
        delete [] log;
        return 2;
    }
    
    GLuint program;
    
    program = glCreateProgram();
    
    glAttachShader(program, vertexShader);
    glAttachShader(program, fragmentShader);
    
    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);
    
    glLinkProgram(program);
    
    GLint linkStatus;
    glGetProgramiv(program, GL_LINK_STATUS, &linkStatus);
    if(linkStatus == GL_FALSE) {
        GLint logLength;
        glGetProgramiv(program, GL_INFO_LOG_LENGTH, &logLength);
        
        char* log = new char[logLength];
        
        glGetProgramInfoLog(program, logLength, 0, log);
        std::cerr << "Program link error:" << log << std::endl;
        
        delete [] log;
        return 2;
    }
    
    glUseProgram(program);
    
    bool loop = true;
    while(loop) {
        glBindVertexArray(vao);
        
        glDrawArrays(GL_TRIANGLES, 0 /* Pas d'offset au début du VBO */, 3);
        
        glBindVertexArray(0);
        
        SDL_GL_SwapBuffers();
        SDL_Event e;
        while(SDL_PollEvent(&e)) {
            if(e.type == SDL_QUIT) {
                loop = false;
            }
        }
    }
    
    glDeleteProgram(program);
    glDeleteVertexArrays(1, &vao);
    glDeleteBuffers(1, &vbo);
    
    SDL_Quit();
    return 0;
}