如果指定了 GL_COLOR_BUFFER_BIT 掩码，glBlitFramebuffer 是否会复制所有颜色附件? [英] Does glBlitFramebuffer copy all color attachments if GL_COLOR_BUFFER_BIT mask is specified?

问题描述

如果我将像素从一个 FBO 复制到另一个 FBO 并且每个像素都有多个(不一定是相同数量的)颜色附件，并且如果我的掩码是 GL_COLOR_BUFFER_BIT，哪些颜色附件(GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, ...., GL_COLOR_ATTACHMENTi) 是否复制?他们都是?如果是，如果这些 FBO 附加了不同数量的颜色缓冲区怎么办?

If I am copying pixels from one FBO to another and each of them have multiple (not necessary the same number) of color attachments, and if my mask is GL_COLOR_BUFFER_BIT, which color attachments (GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, ...., GL_COLOR_ATTACHMENTi) does it copy? All of them? If yes, what if these FBOs have different number of color buffers attached to them?

假设有2个FBO以这种方式绑定:

Assume that there are 2 FBOs that are bound in this way:

glBindFramebuffer(GL_READ_FRAMEBUFFER, fbo1); 
glBindFramebuffer(GL_DRAW_FRAMEBUFFER, fbo2); 

请注意，fbo1 有 2 个颜色附件，fbo2 有 4 个颜色附件.

Note that fbo1 has 2 color attachments and fbo2 has 4 color attachments.

那么在这种情况下 glBlitFrameBuffer 是如何 blit 颜色附件的?

So how does the glBlitFrameBuffer blit color attachments in this case?

我无法在 OpenGL 文档中的任何地方找到它.

I could not find this anywhere in the OpenGL documentation.

推荐答案

A framebuffer color blitting operation 将 仅从当前glReadBuffer中读取GL_READ_FRAMEBUFFER，它会只写入glDrawBuffers 为 GL_DRAW_FRAMEBUFFER 指定.所以这不是关于附件；这是关于两个帧缓冲区的读取和绘制缓冲区.

A framebuffer color blitting operation will only read from the current glReadBuffer for the GL_READ_FRAMEBUFFER, and it will only write to the glDrawBuffers specified for the GL_DRAW_FRAMEBUFFER. So it's not about the attachments; it's about the read and draw buffers of the two framebuffers.

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