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metal: Fix SDL_RenderReadPixels to wait for the GPU to finish rendering to the active texture before reading its pixels.

This commit is contained in:
Alex Szpakowski 2018-10-13 03:36:42 -03:00
parent d8022d19b4
commit 8c41e2624e
1 changed files with 22 additions and 2 deletions
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24
src/render/metal/SDL_render_metal.m
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@ -1351,10 +1351,23 @@ static int
METAL_RenderReadPixels(SDL_Renderer * renderer, const SDL_Rect * rect, METAL_RenderReadPixels(SDL_Renderer * renderer, const SDL_Rect * rect,
Uint32 pixel_format, void * pixels, int pitch) Uint32 pixel_format, void * pixels, int pitch)
{ @autoreleasepool { { @autoreleasepool {
METAL_RenderData *data = (__bridge METAL_RenderData *) renderer->driverdata;
/* Make sure we have a valid MTLTexture to read from, and an active command
* buffer we can wait for. */
METAL_ActivateRenderCommandEncoder(renderer, MTLLoadActionLoad); METAL_ActivateRenderCommandEncoder(renderer, MTLLoadActionLoad);
// !!! FIXME: this probably needs to commit the current command buffer, and probably waitUntilCompleted /* Wait for the current command buffer to finish, so we don't read from the
METAL_RenderData *data = (__bridge METAL_RenderData *) renderer->driverdata; * texture before the GPU finishes rendering to it. */
if (data.mtlcmdencoder) {
[data.mtlcmdencoder endEncoding];
[data.mtlcmdbuffer commit];
[data.mtlcmdbuffer waitUntilCompleted];
data.mtlcmdencoder = nil;
data.mtlcmdbuffer = nil;
}
id<MTLTexture> mtltexture = data.mtlpassdesc.colorAttachments[0].texture; id<MTLTexture> mtltexture = data.mtlpassdesc.colorAttachments[0].texture;
MTLRegion mtlregion = MTLRegionMake2D(rect->x, rect->y, rect->w, rect->h); MTLRegion mtlregion = MTLRegionMake2D(rect->x, rect->y, rect->w, rect->h);
@ -1370,6 +1383,13 @@ METAL_RenderReadPixels(SDL_Renderer * renderer, const SDL_Rect * rect,
const Uint32 temp_format = (mtltexture.pixelFormat == MTLPixelFormatBGRA8Unorm) ? SDL_PIXELFORMAT_ARGB8888 : SDL_PIXELFORMAT_ABGR8888; const Uint32 temp_format = (mtltexture.pixelFormat == MTLPixelFormatBGRA8Unorm) ? SDL_PIXELFORMAT_ARGB8888 : SDL_PIXELFORMAT_ABGR8888;
const int status = SDL_ConvertPixels(rect->w, rect->h, temp_format, temp_pixels, temp_pitch, pixel_format, pixels, pitch); const int status = SDL_ConvertPixels(rect->w, rect->h, temp_format, temp_pixels, temp_pitch, pixel_format, pixels, pitch);
SDL_free(temp_pixels); SDL_free(temp_pixels);
/* Set up an active command buffer and encoder once we're done. It will use
* the same texture that was active before (even if it's part of the swap
* chain), since we didn't clear that when waiting for the command buffer to
* complete. */
METAL_ActivateRenderCommandEncoder(renderer, MTLLoadActionLoad);
return status; return status;
}} }}