rhi: metal: Make base vertex and instance support optional

Like we do for OpenGL. Conveniently enough the QRhi feature flags are
readily available.

This should prevent errors such as:

MTLValidateFeatureSupport:3901: failed assertion `Base Vertex Instance
Drawing is not supported on this device'

on the iOS Simulator. It is not clear since which version or SDK this
became a fatal problem, but the base vertex/instance support is indeed
an optional feature according to the Metal Feature set tables, so not
calling the drawIndexedPrimitives variant taking baseVertex and
baseInstance when the reported iOS GPU family is too low is the right
thing to do regardless.

Pick-to: 6.2 6.1
Fixes: QTBUG-95795
Change-Id: I47c54a77a66a0410b86b8d4e5a1863dc730490f4
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/gui/rhi/qrhimetal_p_p.h b/src/gui/rhi/qrhimetal_p_p.h
index 3a22b76b22..eed9afc9f1 100644
--- a/src/gui/rhi/qrhimetal_p_p.h
+++ b/src/gui/rhi/qrhimetal_p_p.h
@@ -476,6 +476,7 @@ public:
 
     struct {
         int maxTextureSize = 4096;
+        bool baseVertexAndInstance = true;
     } caps;
 
     QRhiMetalData *d = nullptr;