C++ Opengl triangles is drawing or not visible at all Translation: Les triangles C++ Opengl sont dessinés ou ne sont pas du tout visibles

Question

Mon code ne montre pas du tout le triangle. J'ai essayé de le déboguer étape par étape mais sans succès. Qu'est-ce qui ne va pas dans mon code?

#include <gl/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>
static unsigned int CompileShader(unsigned int type, const std::string& source)
{
    unsigned int id = glCreateShader(type);
    const char* src = source.c_str();
    glShaderSource(id, 1, &src, nullptr);
    glCompileShader(id);

    int result;
    glGetShaderiv(id, GL_COMPILE_STATUS, &result);

    if (result == GL_FALSE)
    {
        int length;
        glGetShaderiv(id, GL_INFO_LOG_LENGTH, &length);
        char* message = (char*)alloca(length * sizeof(char));
        glGetShaderInfoLog(id, length, &length, message);
        std::cout << "Échec de la compilation du shader " << (type == GL_VERTEX_SHADER ? "vertex" : "fragment") << std::endl;
        std::cout << message << std::endl;
        glDeleteShader(id);
        return 0;
    }
    return id;
}

static unsigned CreateShader(const std::string& vertexShader, const std::string& fragmentShader)
{
    unsigned int program = glCreateProgram();
    unsigned int vs = CompileShader(GL_VERTEX_SHADER, vertexShader);
    unsigned int fs = CompileShader(GL_FRAGMENT_SHADER, fragmentShader);

    glAttachShader(program, vs);
    glAttachShader(program, fs);
    glLinkProgram(program);
    glValidateProgram(program);

    glDeleteShader(vs);
    glDeleteShader(fs);

    return program;
}

int main(void)
{
    GLFWwindow* window;

    /* Initialize the library */
    if (!glfwInit())
        return -1;

    /* Create a windowed mode window and its OpenGL context */
    window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
    if (!window)
    {
        glfwTerminate();
        return -1;
    }

    /* Make the window's context current */
    glfwMakeContextCurrent(window);

    if (glewInit() != GLEW_OK)
        std::cout << "Erreur!" << std::endl;

    float positions[6] = {-0.5f, -0.5f, 0.0f, 0.0f, 0.5f, 0.5f};

    unsigned int buffer = 0;
    glGenBuffers(1, &buffer);
    glBindBuffer(GL_ARRAY_BUFFER, buffer);
    glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(float), positions, GL_STATIC_DRAW);

    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, 0);

    std::string vertexShader =
        "#version 330 core\n"
        "\n"
        "layout(location=0)in vec4 position;\n"
        "\n"
        "void main()\n"
        "{\n"
        "   gl_Position = position;\n"
        "}\n";

    std::string fragmentShader =
        "#version 330 core\n"
        "\n"
        "layout(location=0)out vec4 color;\n"
        "\n"
        "void main()\n"
        "{\n"
        "   color = vec4(0.0, 0.0, 1.0, 1.0);\n"
        "}\n";

    unsigned int shader = CreateShader(vertexShader, fragmentShader);
    glUseProgram(shader);
    /* Loop until the user closes the window */
    while (!glfwWindowShouldClose(window))
    {
        /* Render here */
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        glBindVertexArray(buffer);

        glDrawArrays(GL_TRIANGLES, 0, 3);
        glfwPollEvents();
        /* Swap front and back buffers */
        glfwSwapBuffers(window);

        /* Poll for and process events */
        glfwPollEvents();
    }
    glDeleteShader(shader);

    glfwTerminate();
    return 0;
}

Answer 1

Votre "triangle" n'est pas un triangle, c'est une ligne, donc vous ne pouvez pas le voir :

float positions[6] = {-0.5f, -0.5f, 0.0f, 0.0f, 0.5f, 0.5f};

Changez-le en :

float positions[6] = {-0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 0.5f};