渲染動態立方體貼圖（OpenGL）

Question

我正在嘗試將場景渲染6次並將其放置在立方體貼圖的側面。 在繼續學習幾何着色器之前，我想先正確地執行此操作，以便一次完成該操作。 代碼如下：

    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
}

我已經修改了先前項目中的代碼，該代碼實現了用於IBL和反射/折射的靜態立方體貼圖。 如果您認為有必要，我將提供着色器代碼。 在此階段，僅呈現亂碼。

最終結果

實際場景

更新大方塊是我的setViewMat函數中的一個錯誤的結果，該錯誤未應用堆疊的轉換。 現在它僅渲染場景，紋理為黑色。 我已經使用AMD gDEBugger來查看生成的立方體貼圖，它只是黑色的。 所以我認為這是我最初的fbo綁定，還是我在第一遍中渲染每一面的方式都是錯誤的。

Answer 1

好的，我終於可以正常工作了。 在setupFBO中，我不應該取消綁定立方體貼圖。 無論如何，我已經發布了更新的pass1,2代碼。 雖然渲染工作很麻煩，但我很難對兩邊進行排序，因為似乎X +，X- ...並未按我預期的那樣映射兩邊。

 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，我通過對多維數據集的每一邊進行顏色編碼來確定排序，不知道為什么會這樣。

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));