我正在尝试使用glReadPixels
函数从深度缓冲区获取深度值。它总是向我返回 0。
首先,我创建深度缓冲区附件:
glGenFramebuffersOES(1, &viewFramebuffer);
glGenRenderbuffersOES(1, &viewRenderbuffer);
glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer);
glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer);
[self.context renderbufferStorage:GL_RENDERBUFFER_OES fromDrawable:(CAEAGLLayer*)self.layer];
glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_RENDERBUFFER_OES, viewRenderbuffer);
glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_WIDTH_OES, &backingWidth);
glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_HEIGHT_OES, &backingHeight);
if (USE_DEPTH_BUFFER)
{
glGenRenderbuffersOES(1, &depthRenderbuffer);
glBindRenderbufferOES(GL_RENDERBUFFER_OES, depthRenderbuffer);
glRenderbufferStorageOES(GL_RENDERBUFFER_OES, GL_DEPTH_COMPONENT16_OES, backingWidth, backingHeight);
glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_DEPTH_ATTACHMENT_OES, GL_RENDERBUFFER_OES, depthRenderbuffer);
}
然后我调用glReadPixels
函数从深度缓冲区获取深度值:
float depth = 0.0f;
glReadPixels(point.x, self.renderUIView.frame.size.height - point.y, 1, 1, GL_DEPTH_COMPONENT16_OES, GL_FLOAT, &depth);
但它不起作用,深度值始终为 0。我尝试从glGetError()
获取错误代码,它返回1280
。我错过了什么设置吗?
OpenGL ES(任何 API 版本)不支持您正在尝试的内容 - 无法在深度缓冲区上使用glReadPixels
。
另外,一般来说,将任何真实3D游戏的glReadPixels
作为主渲染循环的一部分是一个"非常糟糕的主意" - 它会强制管道刷新,这将完全杀死您的性能。