C++ OpenGL紋理立方體缺失三角形

Question

在我的OpenGL旅程中，當我遇到這個問題時，我試圖製作一個紋理立方體： 只有部分我的立方體被渲染。應該有12個三角形，但只有3個正在渲染。我看過很多教程，但似乎無法找到我們的代碼之間的問題/主要區別。這裏是我的：

... 

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; 
} 

只要你知道，錯誤的是不與setupGLFW()，setupApple()，setupGLEW()，getProgramFromFiles()，calculateMVP()，loadBMP()，或者我的頂點和片段着色器，這是在不同的文件。編譯沒有問題，因爲我有GLFW和GLEW從myglutils.h這是uvtemplate.bmp，其512×512的圖像：

如果你們能幫助我，那將是極大的讚賞。謝謝！

Answer 1

問題是致電glBufferData()。您可以在浮點數中設置大小，但是您必須以字節爲單位指定它的大小（usig sizeof(GLfloat)）。這就是爲什麼OpenGL沒有收到你所有的數據。

空隙glBufferData（GLenum目標， GLsizeiptr大小， 常量GLvoid *數據， GLenum使用）;

所以你需要更換
glBufferData(GL_ARRAY_BUFFER, vertices * 3, points, GL_STATIC_DRAW);
和
glBufferData(GL_ARRAY_BUFFER, vertices * 2, textureCoords, GL_STATIC_DRAW);
與
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);