在一個類中創建Opengl，VAO

Question

初始化main.cpp文件中的VAO，並使它們按預期工作。然而，當我完全一樣的初始化代碼移到一個單獨的類，導致無法找到我的制服（？優化掉了）

當的main.cpp文件中初始化數組對象（正常工作）：

GLuint createCube(){ 
    GLuint VBO; 
    GLuint VAO; 
    GLuint EAO; 
    GLfloat vertexData[] = { 
     0.5f, -0.5f, -0.5f, 
     0.5f, -0.5f, 0.5f, 
     -0.5f, -0.5f, 0.5f, 
     -0.5f, -0.5f, -0.5f, 
     0.5f, 0.5f, -0.5f, 
     0.5f, 0.5f, 0.5f, 
     -0.5f, 0.5f, 0.5f, 
     -0.5f, 0.5f, -0.5f, 

    }; 
    GLuint elementData[] = { 
     2-1, 3-1, 4-1, 
     8-1, 7-1, 6-1, 
     5-1, 6-1, 2-1, 
     6-1, 7-1, 3-1, 
     3-1, 7-1, 8-1, 
     1-1, 4-1, 8-1, 
     1-1, 2-1, 4-1, 
     5-1, 8-1, 6-1, 
     1-1, 5-1, 2-1, 
     2-1, 6-1, 3-1, 
     4-1, 3-1, 8-1, 
     5-1, 1-1, 8-1, 

    }; 

    // make and bind the VAO 
    glGenVertexArrays(1, &VAO); 
    glBindVertexArray(VAO); 

    // make and bind the VBO 
    glGenBuffers(1, &VBO); 
    glBindBuffer(GL_ARRAY_BUFFER, VBO); 

    // make and bind the eao 
    glGenBuffers(1, &EAO); 
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EAO); 

    //put data into VBO and EAO 
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertexData), vertexData, GL_STATIC_DRAW); 
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(elementData), elementData, GL_STATIC_DRAW); 


    // connect the xyz to the "vert" attribute of the vertex shader 
    glEnableVertexAttribArray(render.get_shader()->attrib("vert")); 
    glVertexAttribPointer(render.get_shader()->attrib("vert"), 3, GL_FLOAT, GL_FALSE, 0, NULL); 

    // unbind the VAO, EAO, VBO 

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

    return VAO; 


} 

int main() 
{ 
    GLuint VAO = createCube(); 
    glm::mat4 MVP = createMVP(); 

    bool running = true; 
    while(running){ 
     running = eventHandler(); 

     render.draw(VAO,36,MVP); 

     ui.swapBuffer(); 
    } 

    return 0; 
} 

在類中初始化數組對象（MVP均勻在我的着色器無法找到，也許最優化了呢？）

class cube{ 
public: 
    cube(Render rendrer) 
    { 
     GLuint VBO; 
     GLuint EAO; 
     GLfloat vertexData[] = { 
      0.5f, -0.5f, -0.5f, 
      0.5f, -0.5f, 0.5f, 
      -0.5f, -0.5f, 0.5f, 
      -0.5f, -0.5f, -0.5f, 
      0.5f, 0.5f, -0.5f, 
      0.5f, 0.5f, 0.5f, 
      -0.5f, 0.5f, 0.5f, 
      -0.5f, 0.5f, -0.5f, 

     }; 
     GLuint elementData[] = { 
      2-1, 3-1, 4-1, 
      8-1, 7-1, 6-1, 
      5-1, 6-1, 2-1, 
      6-1, 7-1, 3-1, 
      3-1, 7-1, 8-1, 
      1-1, 4-1, 8-1, 
      1-1, 2-1, 4-1, 
      5-1, 8-1, 6-1, 
      1-1, 5-1, 2-1, 
      2-1, 6-1, 3-1, 
      4-1, 3-1, 8-1, 
      5-1, 1-1, 8-1, 

     }; 

     // make and bind the VAO 
     glGenVertexArrays(1, &VAO); 
     glBindVertexArray(VAO); 

     // make and bind the VBO 
     glGenBuffers(1, &VBO); 
     glBindBuffer(GL_ARRAY_BUFFER, VBO); 

     // make and bind the eao 
     glGenBuffers(1, &EAO); 
     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EAO); 

     //put data into VBO and EAO 
     glBufferData(GL_ARRAY_BUFFER, sizeof(vertexData), vertexData, GL_STATIC_DRAW); 
     glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(elementData), elementData, GL_STATIC_DRAW); 


     // connect the xyz to the "vert" attribute of the vertex shader 
     glEnableVertexAttribArray(rendrer.get_shader()->attrib("vert")); 
     glVertexAttribPointer(rendrer.get_shader()->attrib("vert"), 3, GL_FLOAT, GL_FALSE, 0, NULL); 

     // unbind the VAO, EAO, VBO 

     glBindVertexArray(0); 
     glBindBuffer(GL_ARRAY_BUFFER, 0); 
     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0); 
    } 
    GLuint get_VAO() const 
    { 
     return VAO; 
    } 
private: 
    GLuint VAO; 
}; 

int main() 
{ 

    cube cube_object(render); 
    GLuint VAO = cube_object.get_VAO(); 
    glm::mat4 MVP = createMVP(); 

    bool running = true; 
    while(running){ 
     running = eventHandler(); 

     render.draw(VAO,36,MVP); 

     ui.swapBuffer(); 
    } 

    return 0; 
} 

這是我的頂點着色器：

#version 430 

in vec3 vert; 
uniform mat4 MVP; 

out vec3 vertout; 

void main(void) 
{ 
    vertout = vert; 
    gl_Position = MVP*vec4(vert, 1.0); 
} 

這裏是我的片段着色器：

#version 430 

in vec3 vertout; 
out vec4 outcolor; 

void main(void) 
{ 

    outcolor = mix(vec4(1,0,0,1),vec4(0,1,0,1),dot(vertout, vertout)); 
} 

中是否引起了MVP統一被刪除類創建VAO，還是別的什麼？

編輯：

我要澄清：對象仍然呈現，但它呈現白色，與MVP統一失蹤。

Answer 1

要使OpenGL操作正常工作，必須有一個OpenGL上下文並在該線程上生效。如果你的「其他」類沒有可用的OpenGL上下文，就好像什麼都沒有創建。更糟糕的是，如果沒有上下文，glGetError可能會返回GL_NO_ERROR，所以只使用它檢查錯誤可能不會顯示該問題。