如何在OpenGL ES 2.0中使用模板缓冲区创建FBO？ [英] How to create a FBO with stencil buffer in OpenGL ES 2.0?

问题描述

我需要在3GS上使用模板缓冲来渲染平面阴影，并且多边形
偏移将不起作用，仍然存在z-fighting问题。所以我使用
模板缓冲区来使阴影正确，它适用于win32 gles2
模拟器，但不适用于iPhone。我在整个
场景中添加了一个后期效果。即使在win32 gles2模拟器上，模板缓冲区也不会工作。

我试图将模板缓冲区附加到FBO，然后屏幕变为
black。这是我的代码，

 
 glGenRenderbuffers（1，&dbo）; //深度缓冲区
 glBindRenderbuffer（GL_RENDERBUFFER，dbo）; 
 glRenderbufferStorage（GL_RENDERBUFFER，GL_DEPTH_COMPONENT24_OES，
 widthGL，heightGL）; 
 
 glGenRenderbuffers（1，&sbo）; //模板缓冲区
 glBindRenderbuffer（GL_RENDERBUFFER，sbo）; 
 glRenderbufferStorage（GL_RENDERBUFFER，GL_STENCIL_INDEX8，widthGL，
 heightGL）; 
 
 glGenFramebuffers（1，&fbo）; 
 glBindFramebuffer（GL_FRAMEBUFFER，fbo）; 
 
 glFramebufferTexture2D（GL_FRAMEBUFFER，GL_COLOR_ATTACHMENT0，
 GL_TEXTURE_2D，tex，0）; 
 glFramebufferRenderbuffer（GL_FRAMEBUFFER，GL_DEPTH_ATTACHMENT，
 GL_RENDERBUFFER，dbo）; 
 glFramebufferRenderbuffer（GL_FRAMEBUFFER，GL_STENCIL_ATTACHMENT，
 GL_RENDERBUFFER，sbo）; //这会使整个屏幕变黑
 

使用STENCIL_SIZE = 8创建eglContext，它没有RTT。

<我尝试为深度缓冲区和
模板缓冲区更改RenderbufferStorage，但它们都不起作用。

我有什么遗漏的吗？模板缓冲区包含
深度缓冲区吗？ （我找不到GL_DEPTH24_STENCIL8 ......）

解决方案

在iOS上的OpenGL ES 2.0中，你必须创建一个组合深度和模板渲染缓冲区使用GL_DEPTH24_STENCIL8_OES，然后将其作为GL_DEPTH_ATTACHMENT和GL_STENCIL_ATTACHMENT附加到绑定的帧缓冲区。

  glGenRenderbuffers（1，& depthStencilRenderbuffer）; 
 glBindRenderbuffer（GL_RENDERBUFFER，depthStencilRenderbuffer）; 
 glFramebufferRenderbuffer（GL_FRAMEBUFFER，GL_DEPTH_ATTACHMENT，GL_RENDERBUFFER，depthStencilRenderbuffer）; 
 glFramebufferRenderbuffer（GL_FRAMEBUFFER，GL_STENCIL_ATTACHMENT，GL_RENDERBUFFER，depthStencilRenderbuffer）; 
  

I need stencil buffer on 3GS to render planar shadow, and polygon offset won't work prefect, still has z-fighting problem. So I use stencil buffer to make the shadow correct, it works on win32 gles2 emulator, but not on iPhone. After I added a post effect to the whole scene. The stencil buffer won't work even on win32 gles2 emulator.

And I tried to attach a stencil buffer to FBO, buf the screen turns to black. Here's my code,

   glGenRenderbuffers(1, &dbo); // depth buffer
   glBindRenderbuffer(GL_RENDERBUFFER, dbo);
   glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24_OES,
widthGL, heightGL);

   glGenRenderbuffers(1, &sbo); // stencil buffer
   glBindRenderbuffer(GL_RENDERBUFFER, sbo);
   glRenderbufferStorage(GL_RENDERBUFFER, GL_STENCIL_INDEX8, widthGL,
heightGL);

   glGenFramebuffers(1, &fbo);
   glBindFramebuffer(GL_FRAMEBUFFER, fbo);

   glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
GL_TEXTURE_2D, tex, 0);
   glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT,
GL_RENDERBUFFER, dbo);
   glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT,
GL_RENDERBUFFER, sbo); // this make the whole screen black.

The eglContext is created with STENCIL_SIZE=8, it works without a RTT.

I tried to change the RenderbufferStorage for both depth buffer and stencil buffer, but none of them works.

Is there anything I have missed? Does the stencil buffer pack with depth buffer? (I cannot find things like GL_DEPTH24_STENCIL8 ...)

解决方案

In OpenGL ES 2.0 on iOS, you have to create a combined depth and stencil renderbuffer using GL_DEPTH24_STENCIL8_OES, and then attach it to the bound framebuffer as both GL_DEPTH_ATTACHMENT and GL_STENCIL_ATTACHMENT.

glGenRenderbuffers(1, &depthStencilRenderbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, depthStencilRenderbuffer);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthStencilRenderbuffer);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, depthStencilRenderbuffer);

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