C++OpenGL：屏幕中不出现三角形

Question

我正在按照教程使用OpenGL在屏幕上画一个三角形。我已经正确地遵循了所有的步骤，但我只得到一个绿色屏幕，没有三角形。

这是我现在的代码。在应用程序初始化期间调用DrawScene，并在每个WM_DRAW中调用ResizeScene。我的问题是：为什么三角形没有显示在我的代码中？

OpenGL版本：4.6

#include "glew.h"

GLuint program;
GLuint VAO, VBO, EBO;

void DrawScene(HWND _hWnd);

void SetupShaders()
{
    const char* vertexSource = {
        "#version 130 core\n"

        "layout (location = 0) in vec3 iPos;\n"

        "void main()\n"
        "{\n"
        "   gl_Position = vec4(iPos, 1.0f);\n"
        "}\n"
        "\0"
    };
    GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexSource, NULL);
    glCompileShader(vertexShader);

    const char* fragmentSource = {
        "#version 130 core\n"

        "out vec4 FragColor;\n"

        "void main()\n"
        "{\n"
        "   FragColor = vec4(1.0f, 0.0f, 1.0f, 1.0f);\n"
        "}\n"
        "\0"
    };
    GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentSource, NULL);
    glCompileShader(fragmentShader);

    program = glCreateProgram();
    glAttachShader(program, vertexShader);
    glAttachShader(program, fragmentShader);
    glBindAttribLocation(program, 0, "iPos");
    glLinkProgram(program);
}
void SetupBuffers()
{
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    glGenBuffers(1, &EBO);

    float vertexData[] = {
        0.0f, 0.0f, 0.0f,
        10.0f, 10.0f, 0.0f,
        10.0f, 0.0f, 0.0f,
        0.0f, 10.0f, 0.0f
    };
    glBindVertexArray(VAO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertexData), vertexData, GL_STATIC_DRAW);

    unsigned int indexData[] = {
        0, 1, 2,
        1, 2, 3
    };
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indexData), indexData, GL_STATIC_DRAW);

    glVertexAttribPointer(0, 3, GL_FLOAT, false, sizeof(float) * 3, (void*)0);
    glEnableVertexAttribArray(0);

    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
    glBindVertexArray(0);
}

void SetupScene(HWND& _hWnd)
{
    static PIXELFORMATDESCRIPTOR pfd =                  // pfd Tells Windows How We Want Things To Be
    {
        sizeof(PIXELFORMATDESCRIPTOR),                  // Size Of This Pixel Format Descriptor
        1,                              // Version Number
        PFD_DRAW_TO_WINDOW |                        // Format Must Support Window
        PFD_SUPPORT_OPENGL |                        // Format Must Support OpenGL
        PFD_DOUBLEBUFFER,                       // Must Support Double Buffering
        PFD_TYPE_RGBA,                          // Request An RGBA Format
        32,                               // Select Our Color Depth
        0, 0, 0, 0, 0, 0,                       // Color Bits Ignored
        0,                              // No Alpha Buffer
        0,                              // Shift Bit Ignored
        0,                              // No Accumulation Buffer
        0, 0, 0, 0,                         // Accumulation Bits Ignored
        16,                             // 16Bit Z-Buffer (Depth Buffer)
        0,                              // No Stencil Buffer
        0,                              // No Auxiliary Buffer
        PFD_MAIN_PLANE,                         // Main Drawing Layer
        0,                              // Reserved
    };
    HDC hdc = GetDC(_hWnd);
    int pf = ChoosePixelFormat(hdc, &pfd);

    SetPixelFormat(hdc, pf, &pfd);
    
    HGLRC hglrc = wglCreateContext(hdc);
    wglMakeCurrent(hdc, hglrc);

    glewInit();

    ShowWindow(_hWnd, SW_SHOW);
    SetForegroundWindow(_hWnd);
    SetFocus(_hWnd);

    SetupShaders();
    SetupBuffers();

}

void ResizeScene(HWND& _hWnd, size_t _width, size_t _height)
{
    if (!_height)
    {
        _height = 1;
    }
    glViewport(0, 0, _width, _height);
    DrawScene(_hWnd);
}

void DrawScene(HWND _hWnd)
{
    HDC hdc = GetDC(_hWnd);

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glClearColor(0.0f, 1.0f, 0.0f, 1.0f);

    glUseProgram(program);
    glBindVertexArray(VAO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_BYTE, 0);

    SwapBuffers(hdc);
}

Answer 1

您确实需要启用调试验证层并检查错误,因为在您的代码中有一大堆容易理解的错误：

>

不要使用GLBindatTribLocation。IPOS已（正确地）绑定到布局位置0，您只是破坏了它。

您没有分离和删除您的着色程序后，您链接的程序，因此泄漏了内存。

不要解除顶点和元素缓冲区与顶点数组的绑定，这是使用顶点数组的全部要点。

与3相关，不要在每次呈现时更改顶点数组的顶点和元素缓冲区。只需设置一次顶点缓冲区。

您告诉OpenGL您的索引元素是gldrawelements中的字节，而是将它们作为32位整数上载。要始终如一。