GPU: Compute Pipeline.

With the compute pipeline calculation can be offloaded to the GPU.
This patch only adds the framework for compute. So no changes for users at
this moment.

NOTE: As this is an OpenGL4.3 feature it must always have a fallback.

Use `GPU_compute_shader_support` to check if compute pipeline can be used.
Check `gpu_shader_compute*` test cases for usage.

This patch also adds support for shader storage buffer objects and device only
vertex/index buffers.

An alternative that had been discussed was adding this to the `GPUBatch`, this
was eventually not chosen as it would lead to more code when used as part of a
shading group. The idea is that we add an `eDRWCommandType` in the near
future.

Reviewed By: fclem

Differential Revision: https://developer.blender.org/D10913

1 files changed, 8 insertions, 0 deletions

diff --git a/source/blender/gpu/opengl/gl_vertex_buffer.hh b/source/blender/gpu/opengl/gl_vertex_buffer.hh
index e2bf6cd00e8..6c38a2225b3 100644
--- a/source/blender/gpu/opengl/gl_vertex_buffer.hh
+++ b/source/blender/gpu/opengl/gl_vertex_buffer.hh
@@ -47,12 +47,19 @@ class GLVertBuf : public VertBuf {
 
   void update_sub(uint start, uint len, void *data) override;
 
+  const void *read() const override;
+  void *unmap(const void *mapped_data) const override;
+
  protected:
   void acquire_data(void) override;
   void resize_data(void) override;
   void release_data(void) override;
   void upload_data(void) override;
   void duplicate_data(VertBuf *dst) override;
+  void bind_as_ssbo(uint binding) override;
+
+ private:
+  bool is_active() const;
 
   MEM_CXX_CLASS_ALLOC_FUNCS("GLVertBuf");
 };
@@ -65,6 +72,7 @@ static inline GLenum to_gl(GPUUsageType type)
     case GPU_USAGE_DYNAMIC:
       return GL_DYNAMIC_DRAW;
     case GPU_USAGE_STATIC:
+    case GPU_USAGE_DEVICE_ONLY:
       return GL_STATIC_DRAW;
     default:
       BLI_assert(0);