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, 11 insertions, 1 deletions

diff --git a/source/blender/gpu/intern/gpu_index_buffer_private.hh b/source/blender/gpu/intern/gpu_index_buffer_private.hh
index 2405db8664a..358258604bf 100644
--- a/source/blender/gpu/intern/gpu_index_buffer_private.hh
+++ b/source/blender/gpu/intern/gpu_index_buffer_private.hh
@@ -75,13 +75,14 @@ class IndexBuf {
 
   void init(uint indices_len, uint32_t *indices);
   void init_subrange(IndexBuf *elem_src, uint start, uint length);
+  void init_build_on_device(uint index_len);
 
   uint32_t index_len_get(void) const
   {
     return index_len_;
   }
   /* Return size in byte of the drawable data buffer range. Actual buffer size might be bigger. */
-  size_t size_get(void)
+  size_t size_get(void) const
   {
     return index_len_ * to_bytesize(index_type_);
   };
@@ -91,6 +92,11 @@ class IndexBuf {
     return is_init_;
   };
 
+  virtual void bind_as_ssbo(uint binding) = 0;
+
+  virtual const uint32_t *read() const = 0;
+  uint32_t *unmap(const uint32_t *mapped_memory) const;
+
  private:
   inline void squeeze_indices_short(uint min_idx, uint max_idx);
   inline uint index_range(uint *r_min, uint *r_max);
@@ -105,6 +111,10 @@ static inline IndexBuf *unwrap(GPUIndexBuf *indexbuf)
 {
   return reinterpret_cast<IndexBuf *>(indexbuf);
 }
+static inline const IndexBuf *unwrap(const GPUIndexBuf *indexbuf)
+{
+  return reinterpret_cast<const IndexBuf *>(indexbuf);
+}
 
 static inline int indices_per_primitive(GPUPrimType prim_type)
 {