[C ++ OpenGL纹理多维数据集缺少三角形

Question

在获得OpenGL能力的过程中，遇到这个问题时，我试图制作一个纹理立方体：仅渲染了我的多维数据集的一部分。应该有12个三角形，但仅渲染3个。我看过许多教程，但似乎找不到我们的代码之间的问题/主要区别。这是我的：

...

int main(int argc, char* argv[]) {
    if (!setupGLFW()) return 1;
    setupApple();

    glfwWindowHint(GLFW_SAMPLES, 4);

    GLFWwindow* window = glfwCreateWindow(WIN_WIDTH, WIN_HEIGHT, "Textured Cube", NULL, NULL);
    if (!window) {
        log_msg(LOG_ERROR, "Could not open a GLFW3 window!\n");

        return 1;
    }

    glfwMakeContextCurrent(window);

    if (!setupGLEW()) return 1;

    glClearColor(0.5, 0.5, 0.5, 1.0);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LESS);

    static const int vertices = 12 * 3;
    static const GLfloat points[] = {
        -1.0, -1.0, -1.0,
        -1.0, -1.0,  1.0,
        -1.0,  1.0,  1.0,
         1.0,  1.0, -1.0,
        -1.0, -1.0, -1.0,
        -1.0,  1.0, -1.0,
         1.0, -1.0,  1.0,
        -1.0, -1.0, -1.0,
         1.0, -1.0, -1.0,
         1.0,  1.0, -1.0,
         1.0, -1.0, -1.0,
        -1.0, -1.0, -1.0,
        -1.0, -1.0, -1.0,
        -1.0,  1.0,  1.0,
        -1.0,  1.0, -1.0,
         1.0, -1.0,  1.0,
        -1.0, -1.0,  1.0,
        -1.0, -1.0, -1.0,
        -1.0,  1.0,  1.0,
        -1.0, -1.0,  1.0,
         1.0, -1.0,  1.0,
         1.0,  1.0,  1.0,
         1.0, -1.0, -1.0,
         1.0,  1.0, -1.0,
         1.0, -1.0, -1.0,
         1.0,  1.0,  1.0,
         1.0, -1.0,  1.0,
         1.0,  1.0,  1.0,
         1.0,  1.0, -1.0,
        -1.0,  1.0, -1.0,
         1.0,  1.0,  1.0,
        -1.0,  1.0, -1.0,
        -1.0,  1.0,  1.0,
         1.0,  1.0,  1.0,
        -1.0,  1.0,  1.0,
         1.0, -1.0,  1.0
    };


    static const GLfloat textureCoords[] = {
        0, 0,
        1, 0,
        0, 1,
        0, 1,
        1, 0,
        1, 1,
        0, 0,
        1, 0,
        0, 1,
        0, 1,
        1, 0,
        1, 1,
        0, 0,
        1, 0,
        0, 1,
        0, 1,
        1, 0,
        1, 1,
        0, 0,
        1, 0,
        0, 1,
        0, 1,
        1, 0,
        1, 1,
        0, 0,
        1, 0,
        0, 1,
        0, 1,
        1, 0,
        1, 1,
        0, 0,
        1, 0,
        0, 1,
        0, 1,
        1, 0,
        1, 1,
    };

    GLuint pointBuffer;
    glGenBuffers(1, &pointBuffer);
    glBindBuffer(GL_ARRAY_BUFFER, pointBuffer);
    glBufferData(GL_ARRAY_BUFFER, vertices * 3, points, GL_STATIC_DRAW);

    GLuint textureBuffer;
    glGenBuffers(1, &textureBuffer);
    glBindBuffer(GL_ARRAY_BUFFER, textureBuffer);
    glBufferData(GL_ARRAY_BUFFER, vertices * 2, textureCoords, GL_STATIC_DRAW);

    GLuint vao;
    glGenVertexArrays(1, &vao);
    glBindVertexArray(vao);
    glBindBuffer(GL_ARRAY_BUFFER, pointBuffer);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, NULL);
    glBindBuffer(GL_ARRAY_BUFFER, textureBuffer);
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, NULL);

    glEnableVertexAttribArray(0);
    glEnableVertexAttribArray(1);

    GLuint program = getProgramFromFiles("text_cube.vs.glsl", "text_cube.fs.glsl");
    glm::mat4 MVP = calculateMVP();
    GLuint texture = loadBMP("uvtemplate.bmp");

    if (!program) {
        log_msg(LOG_ERROR, "There was a problem opening shader.\n");

        // clean up
        return 1;
    }

    if (!texture) {
        log_msg(LOG_ERROR, "There was a problem opening shader.\n");

        // clean up
        return 1;
    }

    glUseProgram(program);

    GLuint MVPID = glGetUniformLocation(program, "MVP");
    GLuint textureID = glGetUniformLocation(program, "cube_texture");

    glUniformMatrix4fv(MVPID, 1, GL_FALSE, &MVP[0][0]);

    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, texture);
    glUniform1i(textureID, 0);

    while (!glfwWindowShouldClose(window) && glfwGetKey(window, GLFW_KEY_ESCAPE) != GLFW_PRESS) {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glDrawArrays(GL_TRIANGLES, 0, vertices);

        glfwPollEvents();
        glfwSwapBuffers(window);
    }

    // clean up
    return 0;
} 

仅请注意，该错误与setupGLFW()，setupApple()，setupGLEW()，getProgramFromFiles()，calculateMVP()，loadBMP()或我的顶点和片段着色器不在同一个文件中无关。编译良好，因为我从GLFW中包含了GLEW和myglutils.h。这是uvtemplate.bmp，它是512x512的图片：如果你们能帮助我，将不胜感激。谢谢！

Answer 1

问题是对glBufferData()的调用。您以浮点数设置大小，但必须使用usig sizeof(GLfloat)以字节为单位指定大小。这就是OpenGL无法接收您所有数据的原因。

void glBufferData（GLenum目标，GLsizeiptr大小，const GLvoid *数据，GLenum用法）；

所以您需要更换glBufferData(GL_ARRAY_BUFFER, vertices * 3, points, GL_STATIC_DRAW);和glBufferData(GL_ARRAY_BUFFER, vertices * 2, textureCoords, GL_STATIC_DRAW);同glBufferData(GL_ARRAY_BUFFER, vertices * 3 * sizeof(GLfloat), points, GL_STATIC_DRAW);和glBufferData(GL_ARRAY_BUFFER, vertices * 2 * sizeof(GLfloat), textureCoords, GL_STATIC_DRAW);