rhi: Add the basic infrastructure for geometry shader support

.. but this will only be supported on Vulkan, OpenGL 3.2+, and Open GL
ES 3.2+ for the time being.

The situation is:

- Vulkan is working.  qsb accepts .geom files already, and QShader has
  existing geometry shader support.

- OpenGL 3.2 and OpenGL ES 3.2 are working.

- D3D11 is not working.  D3D11 supports geometry shaders, but SPIRV-
  Cross does not support translating geometry shaders to HLSL.

- Metal is not working.  Metal does not directly support geometry
  shaders.

Change-Id: Ieb7c44c58b8be5f2e2197bf5133cf6847e6c132d
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

1 files changed, 6 insertions, 3 deletions

diff --git a/src/gui/rhi/qrhi_p.h b/src/gui/rhi/qrhi_p.h
index b0cf9e3469..972aed6fd8 100644
--- a/src/gui/rhi/qrhi_p.h
+++ b/src/gui/rhi/qrhi_p.h
@@ -297,6 +297,7 @@ public:
         Vertex,
         TessellationControl,
         TessellationEvaluation,
+        Geometry,
         Fragment,
         Compute
     };
@@ -351,8 +352,9 @@ public:
         VertexStage = 1 << 0,
         TessellationControlStage = 1 << 1,
         TessellationEvaluationStage = 1 << 2,
-        FragmentStage = 1 << 3,
-        ComputeStage = 1 << 4
+        GeometryStage = 1 << 3,
+        FragmentStage = 1 << 4,
+        ComputeStage = 1 << 5
     };
     Q_DECLARE_FLAGS(StageFlags, StageFlag)
 
@@ -1673,7 +1675,8 @@ public:
         ThreeDimensionalTextures,
         RenderTo3DTextureSlice,
         TextureArrays,
-        Tessellation
+        Tessellation,
+        GeometryShader
     };
 
     enum BeginFrameFlag {