iOS5 是否同时支持 GL_STENCIL_INDEX 和 GL_STENCIL_INDEX8？

Question

使用以下代码：

GLuint viewRenderbuffer, viewFramebuffer, viewDepthbuffer, stencilBuffer;
// Create the framebuffer object
glGenFramebuffers(1, &viewFramebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer);

// Create a render buffer and bind it to the FBO.
glGenRenderbuffers(1, &viewRenderbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);
[context renderbufferStorage:GL_RENDERBUFFER fromDrawable:(CAEAGLLayer*)self.layer];
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, viewRenderbuffer);
glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &imageWidth);
glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &imageHeight);

// Create a depth buffer and bind it to the FBO.
glGenRenderbuffers(1, &viewDepthbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, viewDepthbuffer);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, imageWidth, imageHeight);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, viewDepthbuffer);

// Create a stencil buffer to crop the rendered scene and bind it to the FBO.
glGenRenderbuffers(1, &stencilBuffer);
glBindRenderbuffer(GL_RENDERBUFFER, stencilBuffer);
glRenderbufferStorage(GL_RENDERBUFFER, GL_STENCIL_INDEX, imageWidth, imageHeight);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, stencilBuffer);

// Check the FBO.
if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
    NSLog(@"Failure with framebuffer generation: %d", glCheckFramebufferStatus(GL_FRAMEBUFFER));
}

使用GL_STENCIL_INDEX，我得到GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT 错误。使用GL_STENCIL_INDEX8，我得到GL_FRAMEBUFFER_UNSUPPORTED 错误。两者都是由最后一个 glFramebufferRenderbuffer() 函数引起的，该函数应该将模板缓冲区绑定到 FBO。

此外，当我检查 GL_RENDERBUFFER_STENCIL_SIZE 的值时，GL_STENCIL_INDEX8 得到了正确的值 (8)，但 GL_STENCIL_INDEX 得到了 0。

有了这个，我就无法获得一个带有模板缓冲区的功能完整的 FBO。是因为GL_STENCIL_INDEX吗？这里应该使用哪一个？

Answer 1

似乎在 OpenGL ES 2.0 中至少在 iOS 上（不确定其他操作系统）您必须创建组合深度缓冲区和模板缓冲区。 我列出了我的设备（带有 iOS 5.0.1 的 iPhone 4）上支持的所有扩展，唯一与模板缓冲区相关的是：

GL_OES_packed_depth_stencil

这表明您必须创建一个组合深度+模板缓冲区（取自 iPhone 3D Programming 一书）

// Create a packed depth stencil buffer.
GLuint depthStencil;
glGenRenderbuffersOES(1, &depthStencil);
glBindRenderbufferOES(GL_RENDERBUFFER_OES, depthStencil);
glRenderbufferStorageOES(GL_RENDERBUFFER_OES, GL_DEPTH24_STENCIL8_OES, width, height);

// Create the framebuffer object.
GLuint framebuffer;
glGenFramebuffersOES(1, &framebuffer);
glBindFramebufferOES(GL_FRAMEBUFFER_OES, framebuffer);
glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES,
                             GL_RENDERBUFFER_OES, color);
glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_DEPTH_ATTACHMENT_OES,
                                GL_RENDERBUFFER_OES, depthStencil);
glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_STENCIL_ATTACHMENT_OES,
                             GL_RENDERBUFFER_OES, depthStencil);
glBindRenderbufferOES(GL_RENDERBUFFER_OES, color);