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metal: SDL_RenderReadPixels on macOS synchronizes the render target's…

… texture data if it's managed, before reading from it.
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slime73 committed Nov 4, 2018
1 parent c9fed27 commit 244b79e194334aa91f2fa5dfb0a11d2b4a62401f
Showing with 16 additions and 2 deletions.
  1. +16 −2 src/render/metal/SDL_render_metal.m
@@ -1196,14 +1196,28 @@ - (void)dealloc
METAL_RenderData *data = (__bridge METAL_RenderData *) renderer->driverdata;
METAL_ActivateRenderCommandEncoder(renderer, MTLLoadActionLoad, NULL);

// Commit any current command buffer, and waitUntilCompleted, so any output is ready to be read.
[data.mtlcmdencoder endEncoding];
id<MTLTexture> mtltexture = data.mtlpassdesc.colorAttachments[0].texture;

#ifdef __MACOSX__
/* on macOS with managed-storage textures, we need to tell the driver to
* update the CPU-side copy of the texture data.
* NOTE: Currently all of our textures are managed on macOS. We'll need some
* extra copying for any private textures. */
if (mtltexture.storageMode == MTLStorageModeManaged) {
id<MTLBlitCommandEncoder> blit = [data.mtlcmdbuffer blitCommandEncoder];
[blit synchronizeResource:mtltexture];
[blit endEncoding];

/* Commit the current command buffer and wait until it's completed, to make
* sure the GPU has finished rendering to it by the time we read it. */
[data.mtlcmdbuffer commit];
[data.mtlcmdbuffer waitUntilCompleted];
data.mtlcmdencoder = nil;
data.mtlcmdbuffer = nil;

id<MTLTexture> mtltexture = data.mtlpassdesc.colorAttachments[0].texture;
MTLRegion mtlregion = MTLRegionMake2D(rect->x, rect->y, rect->w, rect->h);

// we only do BGRA8 or RGBA8 at the moment, so 4 will do.

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