Cycles: refactor API for GPU display

* Split GPUDisplay into two classes. PathTraceDisplay to implement the Cycles side,
  and DisplayDriver to implement the host application side. The DisplayDriver is now
  a fully abstract base class, embedded in the PathTraceDisplay.
* Move copy_pixels_to_texture implementation out of the host side into the Cycles side,
  since it can be implemented in terms of the texture buffer mapping.
* Move definition of DeviceGraphicsInteropDestination into display driver header, so
  that we do not need to expose private device headers in the public API.
* Add more detailed comments about how the DisplayDriver should be implemented.

The "driver" terminology might not be obvious, but is also used in other renderers.

Differential Revision: https://developer.blender.org/D12626

2 files changed, 21 insertions, 6 deletions

diff --git a/intern/cycles/device/hip/graphics_interop.cpp b/intern/cycles/device/hip/graphics_interop.cpp
index add6dbed5e1..0d5d71019b3 100644
--- a/intern/cycles/device/hip/graphics_interop.cpp
+++ b/intern/cycles/device/hip/graphics_interop.cpp
@@ -37,11 +37,15 @@ HIPDeviceGraphicsInterop::~HIPDeviceGraphicsInterop()
   }
 }
 
-void HIPDeviceGraphicsInterop::set_destination(const DeviceGraphicsInteropDestination &destination)
+void HIPDeviceGraphicsInterop::set_display_interop(
+    const DisplayDriver::GraphicsInterop &display_interop)
 {
-  const int64_t new_buffer_area = int64_t(destination.buffer_width) * destination.buffer_height;
+  const int64_t new_buffer_area = int64_t(display_interop.buffer_width) *
+                                  display_interop.buffer_height;
 
-  if (opengl_pbo_id_ == destination.opengl_pbo_id && buffer_area_ == new_buffer_area) {
+  need_clear_ = display_interop.need_clear;
+
+  if (opengl_pbo_id_ == display_interop.opengl_pbo_id && buffer_area_ == new_buffer_area) {
     return;
   }
 
@@ -52,12 +56,12 @@ void HIPDeviceGraphicsInterop::set_destination(const DeviceGraphicsInteropDestin
   }
 
   const hipError_t result = hipGraphicsGLRegisterBuffer(
-      &hip_graphics_resource_, destination.opengl_pbo_id, hipGraphicsRegisterFlagsNone);
+      &hip_graphics_resource_, display_interop.opengl_pbo_id, hipGraphicsRegisterFlagsNone);
   if (result != hipSuccess) {
     LOG(ERROR) << "Error registering OpenGL buffer: " << hipewErrorString(result);
   }
 
-  opengl_pbo_id_ = destination.opengl_pbo_id;
+  opengl_pbo_id_ = display_interop.opengl_pbo_id;
   buffer_area_ = new_buffer_area;
 }
 
@@ -77,6 +81,14 @@ device_ptr HIPDeviceGraphicsInterop::map()
   hip_device_assert(
       device_, hipGraphicsResourceGetMappedPointer(&hip_buffer, &bytes, hip_graphics_resource_));
 
+  if (need_clear_) {
+    hip_device_assert(
+        device_,
+        hipMemsetD8Async(static_cast<hipDeviceptr_t>(hip_buffer), 0, bytes, queue_->stream()));
+
+    need_clear_ = false;
+  }
+
   return static_cast<device_ptr>(hip_buffer);
 }
 
diff --git a/intern/cycles/device/hip/graphics_interop.h b/intern/cycles/device/hip/graphics_interop.h
index adcaa13a2d7..2b2d287ff6c 100644
--- a/intern/cycles/device/hip/graphics_interop.h
+++ b/intern/cycles/device/hip/graphics_interop.h
@@ -39,7 +39,7 @@ class HIPDeviceGraphicsInterop : public DeviceGraphicsInterop {
   HIPDeviceGraphicsInterop &operator=(const HIPDeviceGraphicsInterop &other) = delete;
   HIPDeviceGraphicsInterop &operator=(HIPDeviceGraphicsInterop &&other) = delete;
 
-  virtual void set_destination(const DeviceGraphicsInteropDestination &destination) override;
+  virtual void set_display_interop(const DisplayDriver::GraphicsInterop &display_interop) override;
 
   virtual device_ptr map() override;
   virtual void unmap() override;
@@ -53,6 +53,9 @@ class HIPDeviceGraphicsInterop : public DeviceGraphicsInterop {
   /* Buffer area in pixels of the corresponding PBO. */
   int64_t buffer_area_ = 0;
 
+  /* The destination was requested to be cleared. */
+  bool need_clear_ = false;
+
   hipGraphicsResource hip_graphics_resource_ = nullptr;
 };