Cycles: Metal graphics interop

This is trivial with unified memory, and avoids one memory copy.

Pull Request: https://projects.blender.org/blender/blender/pulls/137363

intern/cycles/device/CMakeLists.txt

@@ -98,6 +98,8 @@ set(SRC_METAL
   metal/device.h
   metal/device_impl.mm
   metal/device_impl.h
+  metal/graphics_interop.mm
+  metal/graphics_interop.h
   metal/kernel.mm
   metal/kernel.h
   metal/queue.mm

intern/cycles/device/cuda/device_impl.cpp

@@ -1122,6 +1122,7 @@ bool CUDADevice::should_use_graphics_interop(const GraphicsInteropDevice &intero
 
       return found;
     }
+    case GraphicsInteropDevice::METAL:
     case GraphicsInteropDevice::NONE: {
       return false;
     }

intern/cycles/device/cuda/graphics_interop.cpp

@@ -86,6 +86,7 @@ void CUDADeviceGraphicsInterop::set_buffer(const GraphicsInteropBuffer &interop_
       cu_external_memory_ptr_ = external_memory_device_ptr;
       break;
     }
+    case GraphicsInteropDevice::METAL:
     case GraphicsInteropDevice::NONE:
       break;
   }

intern/cycles/device/hip/device_impl.cpp

@@ -1069,6 +1069,7 @@ bool HIPDevice::should_use_graphics_interop(const GraphicsInteropDevice &interop
       return found;
     }
     case GraphicsInteropDevice::VULKAN:
+    case GraphicsInteropDevice::METAL:
     case GraphicsInteropDevice::NONE:
       /* TODO: Implement Vulkan support. */
       return false;

intern/cycles/device/hip/graphics_interop.cpp

@@ -56,9 +56,10 @@ void HIPDeviceGraphicsInterop::set_buffer(const GraphicsInteropBuffer &interop_b
       }
       break;
     }
-    /* TODO: implement vulkan support. */
     case GraphicsInteropDevice::VULKAN:
+    case GraphicsInteropDevice::METAL:
     case GraphicsInteropDevice::NONE:
+      /* TODO: implement vulkan support. */
       break;
   }
 }

intern/cycles/device/metal/device_impl.mm

@@ -12,6 +12,8 @@
 
 #  include "scene/scene.h"
 
+#  include "session/display_driver.h"
+
 #  include "util/debug.h"
 #  include "util/md5.h"
 #  include "util/path.h"
@@ -1360,11 +1362,11 @@ unique_ptr<DeviceQueue> MetalDevice::gpu_queue_create()
   return make_unique<MetalDeviceQueue>(this);
 }
 
-bool MetalDevice::should_use_graphics_interop(const GraphicsInteropDevice & /*interop_device*/,
+bool MetalDevice::should_use_graphics_interop(const GraphicsInteropDevice &interop_device,
                                               const bool /*log*/)
 {
-  /* METAL_WIP - provide fast interop */
-  return false;
+  /* Always supported with unified memory. */
+  return interop_device.type == GraphicsInteropDevice::METAL;
 }
 
 void *MetalDevice::get_native_buffer(device_ptr ptr)

intern/cycles/device/metal/graphics_interop.h

@@ -0,0 +1,46 @@
+/* SPDX-FileCopyrightText: 2025 Blender Foundation
+ *
+ * SPDX-License-Identifier: Apache-2.0 */
+
+#ifdef WITH_METAL
+
+#  include "device/graphics_interop.h"
+#  include "session/display_driver.h"
+
+CCL_NAMESPACE_BEGIN
+
+class MetalDevice;
+class MetalDeviceQueue;
+
+class MetalDeviceGraphicsInterop : public DeviceGraphicsInterop {
+ public:
+  explicit MetalDeviceGraphicsInterop(MetalDeviceQueue *queue);
+
+  MetalDeviceGraphicsInterop(const MetalDeviceGraphicsInterop &other) = delete;
+  MetalDeviceGraphicsInterop(MetalDeviceGraphicsInterop &&other) noexcept = delete;
+
+  ~MetalDeviceGraphicsInterop() override;
+
+  MetalDeviceGraphicsInterop &operator=(const MetalDeviceGraphicsInterop &other) = delete;
+  MetalDeviceGraphicsInterop &operator=(MetalDeviceGraphicsInterop &&other) = delete;
+
+  void set_buffer(const GraphicsInteropBuffer &interop_buffer) override;
+
+  device_ptr map() override;
+  void unmap() override;
+
+ protected:
+  MetalDeviceQueue *queue_ = nullptr;
+  MetalDevice *device_ = nullptr;
+
+  /* Native handle. */
+  void *buffer_ = nullptr;
+  size_t size_ = 0;
+
+  /* The destination was requested to be cleared. */
+  bool need_clear_ = false;
+};
+
+CCL_NAMESPACE_END
+
+#endif

intern/cycles/device/metal/graphics_interop.mm

@@ -0,0 +1,43 @@
+/* SPDX-FileCopyrightText: 2025 Blender Foundation
+ *
+ * SPDX-License-Identifier: Apache-2.0 */
+
+#ifdef WITH_METAL
+
+#  include "device/metal/graphics_interop.h"
+
+#  include "device/metal/device_impl.h"
+
+CCL_NAMESPACE_BEGIN
+
+MetalDeviceGraphicsInterop::MetalDeviceGraphicsInterop(MetalDeviceQueue *queue)
+    : queue_(queue), device_(static_cast<MetalDevice *>(queue->device))
+{
+}
+
+MetalDeviceGraphicsInterop::~MetalDeviceGraphicsInterop() = default;
+
+void MetalDeviceGraphicsInterop::set_buffer(const GraphicsInteropBuffer &interop_buffer)
+{
+  /* Trivial implementation due to unified memory. */
+  if (interop_buffer.type == GraphicsInteropDevice::METAL) {
+    need_clear_ |= interop_buffer.need_clear;
+    buffer_ = reinterpret_cast<void *>(interop_buffer.handle);
+    size_ = interop_buffer.width * interop_buffer.height * sizeof(half4);
+  }
+}
+
+device_ptr MetalDeviceGraphicsInterop::map()
+{
+  if (buffer_ && need_clear_) {
+    memset(buffer_, 0, size_);
+  }
+
+  return device_ptr(buffer_);
+}
+
+void MetalDeviceGraphicsInterop::unmap() {}
+
+CCL_NAMESPACE_END
+
+#endif

intern/cycles/device/metal/queue.h

@@ -44,6 +44,8 @@ class MetalDeviceQueue : public DeviceQueue {
 
   void *native_queue() override;
 
+  unique_ptr<DeviceGraphicsInterop> graphics_interop_create() override;
+
  protected:
   void setup_capture();
   void update_capture(DeviceKernel kernel);

intern/cycles/device/metal/queue.mm

@@ -10,6 +10,7 @@
 #  include "device/metal/queue.h"
 
 #  include "device/metal/device_impl.h"
+#  include "device/metal/graphics_interop.h"
 #  include "device/metal/kernel.h"
 
 #  include "util/path.h"
@@ -857,6 +858,11 @@ void *MetalDeviceQueue::native_queue()
   return mtlCommandQueue_;
 }
 
+unique_ptr<DeviceGraphicsInterop> MetalDeviceQueue::graphics_interop_create()
+{
+  return make_unique<MetalDeviceGraphicsInterop>(this);
+}
+
 CCL_NAMESPACE_END
 
 #endif /* WITH_METAL */

intern/cycles/session/display_driver.h

@@ -18,6 +18,7 @@ class GraphicsInteropDevice {
     NONE,
     OPENGL,
     VULKAN,
+    METAL,
   };
 
   Type type = NONE;
@@ -39,7 +40,8 @@ class GraphicsInteropBuffer {
   /* The handle is expected to be:
    * - OpenGL: pixel buffer object ID.
    * - Vulkan on Windows: opaque handle for VkBuffer.
-   * - Vulkan on Unix: opaque file descriptor for VkBuffer. */
+   * - Vulkan on Unix: opaque file descriptor for VkBuffer.
+   * - Metal: pixel buffer unified memory pointer. */
   GraphicsInteropDevice::Type type = GraphicsInteropDevice::NONE;
   int64_t handle = 0;
 

source/blender/gpu/metal/mtl_texture.mm

@@ -2649,11 +2649,15 @@ GPUPixelBufferNativeHandle MTLPixelBuffer::get_native_handle()
 {
   GPUPixelBufferNativeHandle native_handle;
 
-  if (buffer_ == nil) {
+  /* Only spported with unified memory currently. */
+  MTLContext *ctx = MTLContext::get();
+  BLI_assert(ctx);
+  if (![ctx->device hasUnifiedMemory]) {
     return native_handle;
   }
 
-  native_handle.handle = reinterpret_cast<int64_t>(buffer_);
+  /* Just get pointer to unified memory. No need to unmap. */
+  native_handle.handle = reinterpret_cast<int64_t>(map());
   native_handle.size = size_;
 
   return native_handle;