渲染动态立方体贴图（OpenGL）

Question

我正在尝试将场景渲染6次并将其放置在立方体贴图的侧面。 在继续学习几何着色器之前，我想先正确地执行此操作，以便一次完成该操作。 代码如下：

    void Scene::setupFBO()
    {
        glGenTextures(1, &cubemap);
        glBindTexture(GL_TEXTURE_CUBE_MAP,cubemap);
        glActiveTexture(GL_TEXTURE0);           
        const int size = 128;           
            // create the fbo
        glGenFramebuffers(1, &fbo);
        glBindFramebuffer(GL_FRAMEBUFFER, fbo);

        for(int i=0;i<6;i++)
        {
            glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB,
                size, size, 0, GL_RGB, GL_UNSIGNED_BYTE, 0);

        }
        glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER,
        GL_LINEAR);
        glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER,
        GL_LINEAR);
        glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S,
        GL_CLAMP_TO_EDGE);
        glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T,
        GL_CLAMP_TO_EDGE);
        glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R,
        GL_CLAMP_TO_EDGE);

        // create the uniform depth buffer
        glGenRenderbuffers(1, &depthbuff);
        glBindRenderbuffer(GL_RENDERBUFFER, depthbuff);
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, size, size);
        //glBindRenderbuffer(GL_RENDERBUFFER, 0);
        GLenum drawBufs[] = {GL_COLOR_ATTACHMENT0};
        // attach it
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, fbo);
        //glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X, cubemap, 0);
        glDrawBuffers(1, drawBufs);

        glBindFramebuffer(GL_FRAMEBUFFER, 0);    
        glBindTexture(GL_TEXTURE_CUBE_MAP, 0);

    }

---

    void Scene::pass1()
    {
        GLuint p = glGetSubroutineIndex(program->id,GL_FRAGMENT_SHADER,"pass1");
        glUniformSubroutinesuiv(GL_FRAGMENT_SHADER,1,&p);

        mat4 view;
        glBindFramebuffer(GL_FRAMEBUFFER, fbo);
        for(int i=0;i<6;i++)
        {
            glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
            glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, cubemap, 0);
            if(i==0) //X+
                cam->Update(vec3(0),vec3(10,0,0)); // position, target
            else if(i==1) //X-
                cam->Update(vec3(0),vec3(-10,0,0));
            else if(i==2) //Y+
                cam->Update(vec3(0),vec3(0,10,0));
            else if(i == 3) //....
                cam->Update(vec3(0),vec3(0,-10,0));
            else if(i == 4)
                cam->Update(vec3(0),vec3(0,0,10));
            else if(i == 5)
                cam->Update(vec3(0),vec3(0,0,-10));

            view = cam->getViewMat();
            for(int ii=1;ii<SHAPE_COUNT;ii++){
                shapes[ii]->setViewMat(view);
                shapes[ii]->Draw();
            }

        }
    }

---

    void Scene::pass2()
    {
        GLuint p = glGetSubroutineIndex(program->id,GL_FRAGMENT_SHADER,"pass2");
        glUniformSubroutinesuiv(GL_FRAGMENT_SHADER,1,&p);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glBindFramebuffer(GL_FRAMEBUFFER, 0);
        cam->Update(vec3(0,0,10),vec3(0));
        mat4 view = cam->getViewMat();
        for(int i=0;i<SHAPE_COUNT;i++){
            shapes[i]->setViewMat(view);
            (*shapes[i]).Draw();
        }
    }

---

void Scene::Draw(){
    pass1(); // Create the cubemap
    pass2(); // Draw the scene normally
}

我已经修改了先前项目中的代码，该代码实现了用于IBL和反射/折射的静态立方体贴图。 如果您认为有必要，我将提供着色器代码。 在此阶段，仅呈现乱码。

最终结果

实际场景

更新大方块是我的setViewMat函数中的一个错误的结果，该错误未应用堆叠的转换。 现在它仅渲染场景，纹理为黑色。 我已经使用AMD gDEBugger来查看生成的立方体贴图，它只是黑色的。 所以我认为这是我最初的fbo绑定，还是我在第一遍中渲染每一面的方式都是错误的。

Answer 1

好的，我终于可以正常工作了。 在setupFBO中，我不应该取消绑定立方体贴图。 无论如何，我已经发布了更新的pass1,2代码。 虽然渲染工作很麻烦，但我很难对两边进行排序，因为似乎X +，X- ...并未按我预期的那样映射两边。

 void Scene::pass1()
  {
    glBindFramebuffer(GL_FRAMEBUFFER, fbo);
    GLuint p = glGetSubroutineIndex(program->id,GL_FRAGMENT_SHADER,"pass1");
    glUniformSubroutinesuiv(GL_FRAGMENT_SHADER,1,&p);
    glViewport(0,0,512,512);
    mat4 view, proj;
    proj = glm::perspective(90.0f, 1.0f, 1.0f, 500.0f);
    for(int i=0;i<6;i++)
    {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
       if(i==0)
          view = Camera::Update(vec3(0),vec3(1,0,0),vec3(0,1,0));// pos, target, up
       else if(i==1)
          view =  Camera::Update(vec3(0),vec3(-1,0,0),vec3(0,1,0));
       else if(i==2)
         view =  Camera::Update(vec3(0),vec3(0,1,0),vec3(0,0,1));
       else if(i == 3)
         view =  Camera::Update(vec3(0),vec3(0,-1,0),vec3(0,0,-1));
       else if(i == 4)
         view =  Camera::Update(vec3(0),vec3(0,0,1),vec3(0,1,0));
       else if(i == 5)
         view =  Camera::Update(vec3(0),vec3(0,0,-1),vec3(0,1,0));
        for(int ii=1;ii<SHAPE_COUNT;ii++){
            shapes[ii]->setProjMat(proj);
            shapes[ii]->setViewMatAndUpdate(view); // Empties the transformation stack, pushes the new view matrix and applies all the transformations again
            shapes[ii]->Draw();
                    //Reverts back to the original stack
            shapes[ii]->setViewMatAndUpdate(cam->getViewMat());
        }
        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
            GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, cubemap,0);
     }
   }

---

void Scene::pass2()
{
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    GLuint p = glGetSubroutineIndex(program->id,GL_FRAGMENT_SHADER,"pass2");
    glUniformSubroutinesuiv(GL_FRAGMENT_SHADER,1,&p);
    glViewport(0,0,Constants::Instance()->gWidth,Constants::Instance()->gHeight);
    float  aspectRatio = 8.0f/6.0f;
    mat4 proj = cam->getProjMat();
    for(int i=0;i<SHAPE_COUNT;i++){
        shapes[i]->setProjMat(proj);
        (*shapes[i]).Draw();
    }
}

---

好的，我通过对多维数据集的每一边进行颜色编码来确定排序，不知道为什么会这样。

if(i==1)
    view = Camera::Update(vec3(0),vec3(1,0,0),vec3(0,1,0));
else if(i==2)
    view =  Camera::Update(vec3(0),vec3(-1,0,0),vec3(0,1,0));
else if(i==4)
    view =  Camera::Update(vec3(0),vec3(0,1,0),vec3(0,0,1));
else if(i == 3)
    view =  Camera::Update(vec3(0),vec3(0,-1,0),vec3(0,0,-1));
else if(i == 0)
    view =  Camera::Update(vec3(0),vec3(0,0,1),vec3(0,1,0));
else if(i == 5)
    view =  Camera::Update(vec3(0),vec3(0,0,-1),vec3(0,1,0));