mtl: report a proper max texture size

try to deal with the nonsense feature set api

src/rhi/qrhimetal.mm

@@ -240,6 +240,29 @@ bool QRhiMetal::create(QRhi::Flags flags)
 
     d->cmdQueue = [d->dev newCommandQueue];
 
+#if defined(Q_OS_MACOS)
+    caps.maxTextureSize = 16384;
+#elif defined(Q_OS_TVOS)
+    if ([d->dev supportsFeatureSet: MTLFeatureSet(30003)]) // MTLFeatureSet_tvOS_GPUFamily2_v1
+        caps.maxTextureSize = 16384;
+    else
+        caps.maxTextureSize = 8192;
+#elif defined(Q_OS_IOS)
+    // welcome to feature set hell
+    if ([d->dev supportsFeatureSet: MTLFeatureSet(16)] // MTLFeatureSet_iOS_GPUFamily5_v1
+            || [d->dev supportsFeatureSet: MTLFeatureSet(11)] // MTLFeatureSet_iOS_GPUFamily4_v1
+            || [d->dev supportsFeatureSet: MTLFeatureSet(4)]) // MTLFeatureSet_iOS_GPUFamily3_v1
+    {
+        caps.maxTextureSize = 16384;
+    } else if ([d->dev supportsFeatureSet: MTLFeatureSet(3)] // MTLFeatureSet_iOS_GPUFamily2_v2
+            || [d->dev supportsFeatureSet: MTLFeatureSet(2)]) // MTLFeatureSet_iOS_GPUFamily1_v2
+    {
+        caps.maxTextureSize = 8192;
+    } else {
+        caps.maxTextureSize = 4096;
+    }
+#endif
+
     nativeHandlesStruct.dev = d->dev;
     nativeHandlesStruct.cmdQueue = d->cmdQueue;
 
@@ -348,7 +371,7 @@ int QRhiMetal::resourceSizeLimit(QRhi::ResourceSizeLimit limit) const
     case QRhi::TextureSizeMin:
         return 1;
     case QRhi::TextureSizeMax:
-        return 16384; // ###
+        return caps.maxTextureSize;
     default:
         Q_UNREACHABLE();
         return 0;

src/rhi/qrhimetal_p.h

@@ -344,6 +344,10 @@ public:
     QSet<QMetalSwapChain *> swapchains;
     QRhiMetalNativeHandles nativeHandlesStruct;
 
+    struct {
+        int maxTextureSize = 4096;
+    } caps;
+
     QRhiMetalData *d = nullptr;
 };
 

todo.txt

 prof report api (fed by a cbor stream)
 gl: debug: object names
 gl: debug: markers (begin, end, msg)
-mtl: max texture size
 prof: report readback temp buf
 multiwindow_threaded should demo pulling out the device and importing to another rhi
 merge offscreen examples into one
@@ -54,6 +53,7 @@ dxc for d3d as an alternative to fxc?
 hlsl -> dxc -> spirv -> spirv-cross hmmm...
 
 +++ done
+mtl: max texture size
 vk: obj name and debug markers
 vk, gl: tex and other prof
 max texture size stuff