This is a sample of usage of native RenderPluginDelegate. It will make screenshots asynchronously on demand.

##Prerequisites

Unity: 2020

iOS: any

In Plugins/iOS folder you can see our UnityAppController subclass (MyAppController.mm) and render plugin implementation (ScreenshotCreator.mm)

MyAppController.mm contains shouldAttachRenderDelegate method override, to register our render plugin:

- (void)shouldAttachRenderDelegate;
{
	self.renderDelegate = [[ScreenshotCreator alloc] init];
}

ScreenshotCreator.mm demonstrates basic steps needed to implement your own plugin.

First, on registering we tweak Unity's Rendering Surface to back backbuffer with CVTextureCache

- (void)onBeforeMainDisplaySurfaceRecreate:(struct RenderingSurfaceParams*)params
{
	params->useCVTextureCache = true;
}

Second, we hook up on the unity rendering at the moment frame was fully rendered. That will be called right before blitting to screen (if resolution is not native) and presenting frame:

- (void)onFrameResolved

Please note, how we use the fact that backbuffer is backed by CVTextureCache:

CVPixelBufferRef pixelBuf = (CVPixelBufferRef)mainDisplaySurface->cvPixelBuffer;

...

// we need to copy data to avoid stalling gl
CVPixelBufferLockBaseAddress(pixelBuf, kCVPixelBufferLock_ReadOnly);
{
	::memcpy(imageBuffer, CVPixelBufferGetBaseAddress(pixelBuf), bufferSize);
}
CVPixelBufferUnlockBaseAddress(pixelBuf, kCVPixelBufferLock_ReadOnly);

And after we copied the contents of the screen we start saving it to image on the background thread:

[self performSelectorInBackground:@selector(saveImage) withObject:NULL];

All other code is very basic saving image to file and some glue to command the plugin from C#.