glCopyTexImage2D 作为 glReadPixels (OpenGL ES) 的替代品 [英] glCopyTexImage2D as alternative to glReadPixels (OpenGL ES)

问题描述

我目前正在使用 glReadPixels 抓取 OpenGL ES 游戏的屏幕截图.屏幕截图很棒，但是对 glReadPixels 的调用会导致游戏出现小问题.

I'm currently grabbing a screenshot of an OpenGL ES game using glReadPixels. The screenshots are great however the call to glReadPixels causes a small stutter in the game.

glCopyTexImage2D 已被建议作为 glReadPixels 的更有效替代品.glCopyTexImage2D 是如何工作的?对于某些情况，我正在使用 这个 Apple 方法.

glCopyTexImage2D has been suggested as a more efficient replacement for glReadPixels. How does glCopyTexImage2D work? For some context I'm using this Apple method.

我对 OpenGL 比较陌生，因此非常感谢任何帮助 :-)

I'm relatively new to OpenGL so any help is much appreciated :-)

推荐答案

时间延迟是由于GPU和CPU之间传输大量内存造成的.这可以通过分块传输来解决，每帧传输一点点.但是，如果您从帧缓冲区中读取一系列帧，则图像会同时发生变化.

The time delay is caused by transferring a large amount of memory between GPU and CPU. This can be solved by transferring in chunks, a little bit per frame. But if you read from the framebuffer over a series of frame, the image would be changing meanwhile.

因此，您将视频 RAM 复制到视频 RAM 中(非常快)，然后它不会随着您零碎地传输而改变.

So you make a copy, video RAM into video RAM (very fast), and then it won't change as you transfer it piecemeal.

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