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, 15 insertions, 3 deletions

diff --git a/intern/cycles/hydra/render_buffer.cpp b/intern/cycles/hydra/render_buffer.cpp
index 4867def0624..4d8b21d1e61 100644
--- a/intern/cycles/hydra/render_buffer.cpp
+++ b/intern/cycles/hydra/render_buffer.cpp
@@ -35,7 +35,7 @@ bool HdCyclesRenderBuffer::Allocate(const GfVec3i &dimensions, HdFormat format,
     return false;
   }
 
-  const size_t oldSize = _data.size();
+  const size_t oldSize = _dataSize;
   const size_t newSize = dimensions[0] * dimensions[1] * HdDataSizeOfFormat(format);
   if (oldSize == newSize) {
     return true;
@@ -49,8 +49,8 @@ bool HdCyclesRenderBuffer::Allocate(const GfVec3i &dimensions, HdFormat format,
   _width = dimensions[0];
   _height = dimensions[1];
   _format = format;
-
-  _data.resize(newSize);
+  _dataSize = newSize;
+  _resourceUsed = false;
 
   return true;
 }
@@ -63,6 +63,7 @@ void HdCyclesRenderBuffer::_Deallocate()
 
   _data.clear();
   _data.shrink_to_fit();
+  _dataSize = 0;
 
   _resource = VtValue();
 }
@@ -74,6 +75,10 @@ void *HdCyclesRenderBuffer::Map()
     return nullptr;
   }
 
+  if (_data.size() != _dataSize) {
+    _data.resize(_dataSize);
+  }
+
   ++_mapped;
 
   return _data.data();
@@ -103,10 +108,17 @@ void HdCyclesRenderBuffer::SetConverged(bool converged)
   _converged = converged;
 }
 
+bool HdCyclesRenderBuffer::IsResourceUsed() const
+{
+  return _resourceUsed;
+}
+
 VtValue HdCyclesRenderBuffer::GetResource(bool multiSampled) const
 {
   TF_UNUSED(multiSampled);
 
+  _resourceUsed = true;
+
   return _resource;
 }