glCopyTexImage2D可以替代glReadPixels(OpenGL ES) [英] glCopyTexImage2D as alternative to glReadPixels (OpenGL ES)

问题描述

我目前正在使用glReadPixels捕获OpenGL ES游戏的屏幕截图.屏幕截图非常棒，但是调用glReadPixels会导致游戏中出现少量停顿现象.

建议使用

glCopyTexImage2D作为glReadPixels的更有效替代. glCopyTexImage2D如何工作?在某些情况下，我使用的是此Apple方法. /p>

我是OpenGL的新手，所以非常感谢您的帮助:-)

解决方案

时间延迟是由于在GPU和CPU之间传输大量内存引起的.这可以通过以每帧一点的方式分块传输来解决.但是，如果您从一系列帧的帧缓冲区中读取图像，则图像将同时发生变化.

因此，您将视频RAM复制到视频RAM(非常快)，然后将其复制，就不会改变.

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

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

解决方案

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.

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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