Remove use of the MTLMaxBlitPassSampleBuffers Metal API definition.
MTLMaxBlitPassSampleBuffers was available in Xcode 12 and had a value of 4.
According to Apple, the definition will be removed from the API in Xcode 13.
For now, assume a value of 1, until we can accurately determine the
appropriate value per platform.
diff --git a/MoltenVK/MoltenVK/Commands/MVKCommandBuffer.mm b/MoltenVK/MoltenVK/Commands/MVKCommandBuffer.mm
index c29db0a..1d75018 100644
--- a/MoltenVK/MoltenVK/Commands/MVKCommandBuffer.mm
+++ b/MoltenVK/MoltenVK/Commands/MVKCommandBuffer.mm
@@ -781,7 +781,7 @@
// Metal stage GPU counters need to be configured in a Metal render, compute, or BLIT encoder, meaning that the
// Metal encoder needs to know about any Vulkan timestamp commands that will be executed during the execution
// of a renderpass, or set of Vulkan dispatch or BLIT commands. In addition, there are a very small number of
-// staged timestamps (4) that can be tracked in any single render, compute, or BLIT pass, meaning a renderpass
+// staged timestamps that can be tracked in any single render, compute, or BLIT pass, meaning a renderpass
// that timestamped after each of many draw calls, would not be trackable. Finally, stage counters are only
// available on tile-based GPU's, which means draw or dispatch calls cannot be individually timestamped.
// We avoid dealing with all this complexity and mismatch between how Vulkan and Metal stage counters operate
@@ -795,8 +795,12 @@
// With each BLIT pass, consume as many outstanding timestamp queries as possible.
// Attach an query result to each of the available sample buffer attachments in the BLIT pass descriptor.
+ // MTLMaxBlitPassSampleBuffers was defined in the Metal API as 4, but according to Apple, will be removed
+ // in Xcode 13 as inaccurate for all platforms. Leave this value at 1 until we can figure out how to
+ // accurately determine the length of sampleBufferAttachments on each platform.
+ uint32_t maxMTLBlitPassSampleBuffers = 1; // Was MTLMaxBlitPassSampleBuffers API definition
auto* bpDesc = [[[MTLBlitPassDescriptor alloc] init] autorelease];
- for (uint32_t attIdx = 0; attIdx < MTLMaxBlitPassSampleBuffers && qIdx < qCnt; attIdx++, qIdx++) {
+ for (uint32_t attIdx = 0; attIdx < maxMTLBlitPassSampleBuffers && qIdx < qCnt; attIdx++, qIdx++) {
auto* sbAttDesc = bpDesc.sampleBufferAttachments[attIdx];
auto& tsQry = _timestampStageCounterQueries[qIdx];
