Log format substitution error when MTLPixelFormatDepth24Unorm_Stencil8 is not supported.

Docs/Whats_New.md

@@ -37,6 +37,7 @@ Released 2019/10/28
 - Allow `MVK_CONFIG_SYNCHRONOUS_QUEUE_SUBMITS` build setting to be overridden.
 - Fix memory leaks of system classes during `VkInstance` and `VkQueue` creation.
 - Fix memory leaks when compiling shaders and pipelines without default OS autorelease pool.
+- Log format substitution error when `MTLPixelFormatDepth24Unorm_Stencil8` is not supported.
 - Reduce memory usage by adjusting default memory allocs for many `MVKVectorInline` uses and 
   replacing use of `MVKVectorDefault` with `std::vector` in descriptor set bindings.
 	 

MoltenVK/MoltenVK/GPUObjects/MVKDevice.mm

@@ -211,8 +211,6 @@ bool MVKPhysicalDevice::getFormatIsSupported(VkFormat format) {
 	switch (mvkMTLPixelFormatFromVkFormat(format)) {
 		case MTLPixelFormatDepth24Unorm_Stencil8:
 			return getMTLDevice().isDepth24Stencil8PixelFormatSupported;
-			break;
-
 		default:
 			break;
 	}
@@ -2512,7 +2510,7 @@ MTLPixelFormat MVKDevice::getMTLPixelFormatFromVkFormat(VkFormat vkFormat, MVKBa
 #if MVK_MACOS
 	if (mtlPixFmt == MTLPixelFormatDepth24Unorm_Stencil8 &&
 		!getMTLDevice().isDepth24Stencil8PixelFormatSupported) {
-		return MTLPixelFormatDepth32Float_Stencil8;
+		return mvkMTLPixelFormatFromVkFormatInObj(vkFormat, mvkObj, MTLPixelFormatDepth24Unorm_Stencil8);
 	}
 #endif
 	return mtlPixFmt;

MoltenVK/MoltenVK/Vulkan/mvk_datatypes.hpp

@@ -47,7 +47,9 @@ class MVKBaseObject;
  * of an MVKBaseObject subclass, which is true for all but static calling functions.
  */
 
-MTLPixelFormat mvkMTLPixelFormatFromVkFormatInObj(VkFormat vkFormat, MVKBaseObject* mvkObj);
+MTLPixelFormat mvkMTLPixelFormatFromVkFormatInObj(VkFormat vkFormat,
+												  MVKBaseObject* mvkObj,
+												  MTLPixelFormat mtlPixelFormatKnownUnsupported = MTLPixelFormatInvalid);
 #define mvkMTLPixelFormatFromVkFormat(vkFormat)	mvkMTLPixelFormatFromVkFormatInObj(vkFormat, this)
 
 MTLVertexFormat mvkMTLVertexFormatFromVkFormatInObj(VkFormat vkFormat, MVKBaseObject* mvkObj);

MoltenVK/MoltenVK/Vulkan/mvk_datatypes.mm

@@ -569,11 +569,13 @@ MVK_PUBLIC_SYMBOL MTLPixelFormat mvkMTLPixelFormatFromVkFormat(VkFormat vkFormat
 	return mvkMTLPixelFormatFromVkFormatInObj(vkFormat, nullptr);
 }
 
-MTLPixelFormat mvkMTLPixelFormatFromVkFormatInObj(VkFormat vkFormat, MVKBaseObject* mvkObj) {
+MTLPixelFormat mvkMTLPixelFormatFromVkFormatInObj(VkFormat vkFormat,
+												  MVKBaseObject* mvkObj,
+												  MTLPixelFormat mtlPixelFormatKnownUnsupported) {
 	MTLPixelFormat mtlPixFmt = MTLPixelFormatInvalid;
 
 	const MVKFormatDesc& fmtDesc = formatDescForVkFormat(vkFormat);
-	if (fmtDesc.isSupported()) {
+	if (fmtDesc.isSupported() && (fmtDesc.mtl != mtlPixelFormatKnownUnsupported)) {
 		mtlPixFmt = fmtDesc.mtl;
 	} else if (vkFormat != VK_FORMAT_UNDEFINED) {
 		// If the MTLPixelFormat is not supported but VkFormat is valid, attempt to substitute a different format.