Fix use of OpenGL interop breaking in Hydra viewports that do not support it

Rendering directly to a resource using OpenGL interop and Hgi
doesn't work in Houdini, since it never uses the resulting resource
(it does not call `HdRenderBuffer::GetResource`). But since doing
that simultaneously disables mapping (`HdRenderBuffer::Map` is
not implemented then), nothing was displayed. To fix this, keep
track of whether a Hydra viewport does support displaying a Hgi
resource directly, by checking whether
`HdRenderBuffer::GetResource` is ever called and only enable use
of OpenGL interop if that is the case.

Differential Revision: https://developer.blender.org/D15090

1 files changed, 4 insertions, 0 deletions

diff --git a/intern/cycles/hydra/render_buffer.h b/intern/cycles/hydra/render_buffer.h
index 8eb874f0068..90629d4aee0 100644
--- a/intern/cycles/hydra/render_buffer.h
+++ b/intern/cycles/hydra/render_buffer.h
@@ -58,6 +58,8 @@ class HdCyclesRenderBuffer final : public PXR_NS::HdRenderBuffer {
 
   void SetConverged(bool converged);
 
+  bool IsResourceUsed() const;
+
   PXR_NS::VtValue GetResource(bool multiSampled = false) const override;
 
   void SetResource(const PXR_NS::VtValue &resource);
@@ -74,9 +76,11 @@ class HdCyclesRenderBuffer final : public PXR_NS::HdRenderBuffer {
   unsigned int _width = 0u;
   unsigned int _height = 0u;
   PXR_NS::HdFormat _format = PXR_NS::HdFormatInvalid;
+  size_t _dataSize = 0;
 
   std::vector<uint8_t> _data;
   PXR_NS::VtValue _resource;
+  mutable std::atomic_bool _resourceUsed = false;
 
   std::atomic_int _mapped = 0;
   std::atomic_bool _converged = false;