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, 4 deletions

diff --git a/intern/cycles/hydra/output_driver.cpp b/intern/cycles/hydra/output_driver.cpp
index c5f64ac1c18..f4ea853f243 100644
--- a/intern/cycles/hydra/output_driver.cpp
+++ b/intern/cycles/hydra/output_driver.cpp
@@ -30,11 +30,11 @@ bool HdCyclesOutputDriver::update_render_tile(const Tile &tile)
   std::vector<float> pixels;
 
   for (const HdRenderPassAovBinding &aovBinding : _renderParam->GetAovBindings()) {
-    if (aovBinding == _renderParam->GetDisplayAovBinding()) {
-      continue;  // Display AOV binding is already updated by Cycles display driver
-    }
-
     if (const auto renderBuffer = static_cast<HdCyclesRenderBuffer *>(aovBinding.renderBuffer)) {
+      if (aovBinding == _renderParam->GetDisplayAovBinding() && renderBuffer->IsResourceUsed()) {
+        continue;  // Display AOV binding is already updated by Cycles display driver
+      }
+
       const HdFormat format = renderBuffer->GetFormat();
       if (format == HdFormatInvalid) {
         continue;  // Skip invalid AOV bindings