From 5c3a6745a2ebc6e5fffbcd3e9a1bc6eae6d80351 Mon Sep 17 00:00:00 2001
From: Michael Jones <michael_p_jones@apple.com>
Date: Thu, 16 Oct 2025 11:50:28 +0200
Subject: [PATCH] Cycles: Forward compatibility for Metal "FastIntersection"
 flag

Follow on from PR #141891. The `MTLAccelerationStructureUsagePreferFastIntersection` flag didn't exist until Xcode 26.0, so we ensure that it is defined for forward-compatibility. The runtime `if (@available(macos 26.0, *))` checks still remain.

Pull Request: https://projects.blender.org/blender/blender/pulls/147561
---
 intern/cycles/device/metal/bvh.mm | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/intern/cycles/device/metal/bvh.mm b/intern/cycles/device/metal/bvh.mm
index d9c96740898..cea9ff68460 100644
--- a/intern/cycles/device/metal/bvh.mm
+++ b/intern/cycles/device/metal/bvh.mm
@@ -35,6 +35,14 @@ CCL_NAMESPACE_BEGIN
 #    define bvh_throttle_printf(...)
 #  endif
 
+/* This flag didn't exist until Xcode 26.0, so we ensure that it is defined for
+ * forward-compatibility.
+ */
+#  ifndef MAC_OS_VERSION_26_0
+#    define MTLAccelerationStructureUsagePreferFastIntersection \
+      MTLAccelerationStructureUsage(1 << 4)
+#  endif
+
 /* Limit the number of concurrent BVH builds so that we don't approach unsafe GPU working set
  * sizes. */
 struct BVHMetalBuildThrottler {
@@ -292,11 +300,9 @@ bool BVHMetal::build_BLAS_mesh(Progress &progress,
       accelDesc.usage |= (MTLAccelerationStructureUsageRefit |
                           MTLAccelerationStructureUsagePreferFastBuild);
     }
-#  if defined(MAC_OS_VERSION_26_0)
     else if (@available(macos 26.0, *)) {
       accelDesc.usage |= MTLAccelerationStructureUsagePreferFastIntersection;
     }
-#  endif
 
     MTLAccelerationStructureSizes accelSizes = [mtl_device
         accelerationStructureSizesWithDescriptor:accelDesc];
@@ -638,11 +644,9 @@ bool BVHMetal::build_BLAS_hair(Progress &progress,
       accelDesc.usage |= (MTLAccelerationStructureUsageRefit |
                           MTLAccelerationStructureUsagePreferFastBuild);
     }
-#    if defined(MAC_OS_VERSION_26_0)
     else if (@available(macos 26.0, *)) {
       accelDesc.usage |= MTLAccelerationStructureUsagePreferFastIntersection;
     }
-#    endif
 
     MTLAccelerationStructureSizes accelSizes = [mtl_device
         accelerationStructureSizesWithDescriptor:accelDesc];
@@ -874,11 +878,9 @@ bool BVHMetal::build_BLAS_pointcloud(Progress &progress,
       accelDesc.usage |= (MTLAccelerationStructureUsageRefit |
                           MTLAccelerationStructureUsagePreferFastBuild);
     }
-#  if defined(MAC_OS_VERSION_26_0)
     else if (@available(macos 26.0, *)) {
       accelDesc.usage |= MTLAccelerationStructureUsagePreferFastIntersection;
     }
-#  endif
 
     MTLAccelerationStructureSizes accelSizes = [mtl_device
         accelerationStructureSizesWithDescriptor:accelDesc];
@@ -1352,11 +1354,9 @@ bool BVHMetal::build_TLAS(Progress &progress,
       accelDesc.usage |= (MTLAccelerationStructureUsageRefit |
                           MTLAccelerationStructureUsagePreferFastBuild);
     }
-#  if defined(MAC_OS_VERSION_26_0)
     else if (@available(macos 26.0, *)) {
       accelDesc.usage |= MTLAccelerationStructureUsagePreferFastIntersection;
     }
-#  endif
 
     MTLAccelerationStructureSizes accelSizes = [mtl_device
         accelerationStructureSizesWithDescriptor:accelDesc];