Question

所以我可以使用OpenGL3.2 +绘制一个旋转的立方体并将其从0,0,0向左平移，但是当我尝试绘制第二个（向右）时，它不会渲染...

这是我的显示功能：

    void display()                                  
    {
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glUseProgram(myShader.handle());

    GLuint matLocation = glGetUniformLocation(myShader.handle(), "ProjectionMatrix");
    glUniformMatrix4fv(matLocation, 1, GL_FALSE, &ProjectionMatrix[0][0]);

    spinY+=0.03;
    if(spinY>360) spinY = 0;

    glm::mat4 viewMatrix;
    viewMatrix = glm::translate(glm::mat4(1.0),glm::vec3(0,0,-100));        //viewing matrix
    ModelViewMatrix = glm::translate(viewMatrix,glm::vec3(-30,0,0));        //translate object from the origin
    ModelViewMatrix = glm::rotate(ModelViewMatrix,spinY, glm::vec3(0,1,0));                 //rotate object about y axis

    glUniformMatrix4fv(glGetUniformLocation(myShader.handle(), "ModelViewMatrix"), 1, GL_FALSE, &ModelViewMatrix[0][0]); //pass matrix to shader

    //Add the following line just before the line to draw the cube to 
    //check that the origin of the cube in eye space is (-30, 0, -100);
    result = glm::vec3(ModelViewMatrix * glm::vec4(0,0,0,1));
    std::cout<<glm::to_string(result)<<std::endl; //print matrix to get coordinates.

    myCube.render();
    glUseProgram(0);
    }

我希望能够使用相同的Cube类/大小等，但只需再次渲染它（我认为这是最有效/最好的方法）。

我试过这个

    void display()                                  
    {
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glUseProgram(myShader.handle());

    GLuint matLocation = glGetUniformLocation(myShader.handle(), "ProjectionMatrix");
    glUniformMatrix4fv(matLocation, 1, GL_FALSE, &ProjectionMatrix[0][0]);

    spinY+=0.03;
    if(spinY>360) spinY = 0;

    glm::mat4 viewMatrix;
    viewMatrix = glm::translate(glm::mat4(1.0),glm::vec3(0,0,-100));        //viewing matrix
    ModelViewMatrix = glm::translate(viewMatrix,glm::vec3(-30,0,0));        //translate object from the origin
    ModelViewMatrix = glm::rotate(ModelViewMatrix,spinY, glm::vec3(0,1,0));                 //rotate object about y axis

    glUniformMatrix4fv(glGetUniformLocation(myShader.handle(), "ModelViewMatrix"), 1, GL_FALSE, &ModelViewMatrix[0][0]); //pass matrix to shader

    //Add the following line just before the line to draw the cube to 
    //check that the origin of the cube in eye space is (-30, 0, -100);
    result = glm::vec3(ModelViewMatrix * glm::vec4(0,0,0,1));
    std::cout<<glm::to_string(result)<<std::endl; //print matrix to get coordinates.

    myCube.render();

    glm::mat4 viewMatrix_TWO;
    viewMatrix_TWO = glm::translate(glm::mat4(1.0),glm::vec3(0,0,-100));        //viewing matrix
    ModelViewMatrix_TWO = glm::translate(viewMatrix_TWO,glm::vec3(30,0,0));     //translate object from the origin
    ModelViewMatrix_TWO = glm::rotate(ModelViewMatrix_TWO,spinY, glm::vec3(0,1,0));                 //rotate object about y axis

    glUniformMatrix4fv(glGetUniformLocation(myShader.handle(), "ModelViewMatrix_TWO"), 1, GL_FALSE, &ModelViewMatrix[0][0]); //pass matrix to shader

    myCube.render();

    glUseProgram(0);
    }

显然，我已经错误地实现了......如何在屏幕的任何一侧获得立方体？感谢。

更新

我意识到，我没有创建第二个多维数据集对象，但现在实现了它，它仍然不起作用...我是否混淆了视图/模型矩阵如何交互？我为每个对象创建了一个新的....

新守则：

myCube.render();

spinX+=0.03;
if(spinX>360) spinX = 0;

glm::mat4 viewMatrix_Two,ModelViewMatrix_Two;
viewMatrix_Two = glm::translate(glm::mat4(1.0),glm::vec3(0,0,-100));        //viewing matrix
ModelViewMatrix_Two = glm::translate(viewMatrix_Two,glm::vec3(30,0,0));     //translate object from the origin
ModelViewMatrix_Two = glm::rotate(ModelViewMatrix_Two,spinX, glm::vec3(0,1,0));                 //rotate object about y axis

glUniformMatrix4fv(glGetUniformLocation(myShader.handle(), "ModelViewMatrix_Two"), 1, GL_FALSE, &ModelViewMatrix_Two[0][0]); //pass matrix to shader

myCube_Two.render();

更新

Shader：

    uniform mat4 ModelViewMatrix;
    //uniform mat4 ModelViewMatrix_Two; //NOT NEEDED - USED SAME SHADER OBJECT
    uniform mat4 ProjectionMatrix;

    in  vec3 in_Position;  // Position coming in
    in  vec3 in_Color;     // colour coming in
    out vec3 ex_Color;     // colour leaving the vertex, this will be sent to the fragment shader

    void main(void)
    {
    gl_Position = ProjectionMatrix * ModelViewMatrix * vec4(in_Position, 1.0);
    //gl_Position = ProjectionMatrix * ModelViewMatrix_Two * vec4(in_Position, 1.0);
    ex_Color = in_Color;
    }

Answer 1

最后，我创建了第二个Cube对象，第二个查看矩阵并将它们与我的着色器中已经建立的模型矩阵一起使用，似乎两个立方体都被单独调用/渲染。

正确的代码是：

    glm::mat4 viewMatrix_Two, ModelViewMatrix_Two;
    viewMatrix_Two = glm::translate(glm::mat4(1.0),glm::vec3(0,0,-200));
    ModelViewMatrix = glm::translate(viewMatrix_Two,glm::vec3(30,0,0));
    ModelViewMatrix = glm::rotate(ModelViewMatrix,spinX, glm::vec3(1,0,0));

    glUniformMatrix4fv(glGetUniformLocation(myShader.handle(), "ModelViewMatrix"), 1, GL_FALSE, &ModelViewMatrix[0][0]); //pass matrix to shader

    myCube_Two.render();

Answer 2

除非你的着色器有一个名为ModelViewMatrix_Two的制服，否则这不起作用。我没有看到你的着色器为模型视图需要另一个制服的原因，因为你没有在同一个调用上绘制两个多维数据集。如果不是问题，您可以发布着色器代码吗？

使用GLM在OpenGL中绘制2个立方体

2 个答案: