2 files changed, 10 insertions, 25 deletions

diff --git a/source/blender/gpu/GPU_index_buffer.h b/source/blender/gpu/GPU_index_buffer.h
index 03d60c60b4b..48f80e321b6 100644
--- a/source/blender/gpu/GPU_index_buffer.h
+++ b/source/blender/gpu/GPU_index_buffer.h
@@ -44,7 +44,6 @@ typedef struct GPUIndexBufBuilder {
   uint index_max;
   GPUPrimType prim_type;
   uint32_t *data;
-  const struct GPUIndexBufBuilder *parent;
 } GPUIndexBufBuilder;
 
 /* supports all primitive types. */
@@ -55,17 +54,12 @@ void GPU_indexbuf_init(GPUIndexBufBuilder *, GPUPrimType, uint prim_len, uint ve
 GPUIndexBuf *GPU_indexbuf_build_on_device(uint index_len);
 
 /*
- * Thread safe sub builders.
+ * Thread safe.
  *
- * Note that `GPU_indexbuf_subbuilder_init` and `GPU_indexbuf_subbuilder_finish` are not thread
- * safe and should be called when no threads are active. The pattern is to create a subbuilder for
- * each thread/task. Each thread/task would update their sub builder. When all thread are completed
- * the sub-builders can then be merged back to the parent builder.
+ * Function inspired by the reduction directives of multithread work APIs..
  */
-void GPU_indexbuf_subbuilder_init(const GPUIndexBufBuilder *parent_builder,
-                                  GPUIndexBufBuilder *sub_builder);
-void GPU_indexbuf_subbuilder_finish(GPUIndexBufBuilder *builder,
-                                    const GPUIndexBufBuilder *parent_builder);
+void GPU_indexbuf_join_copies(GPUIndexBufBuilder *builder,
+                              const GPUIndexBufBuilder *parent_builder);
 
 void GPU_indexbuf_add_generic_vert(GPUIndexBufBuilder *, uint v);
 void GPU_indexbuf_add_primitive_restart(GPUIndexBufBuilder *);
diff --git a/source/blender/gpu/intern/gpu_index_buffer.cc b/source/blender/gpu/intern/gpu_index_buffer.cc
index 3cdcaac5544..993bcdf743b 100644
--- a/source/blender/gpu/intern/gpu_index_buffer.cc
+++ b/source/blender/gpu/intern/gpu_index_buffer.cc
@@ -57,7 +57,6 @@ void GPU_indexbuf_init_ex(GPUIndexBufBuilder *builder,
   builder->index_max = 0;
   builder->prim_type = prim_type;
   builder->data = (uint *)MEM_callocN(builder->max_index_len * sizeof(uint), "GPUIndexBuf data");
-  builder->parent = nullptr;
 }
 
 void GPU_indexbuf_init(GPUIndexBufBuilder *builder,
@@ -80,21 +79,13 @@ GPUIndexBuf *GPU_indexbuf_build_on_device(uint index_len)
   return elem_;
 }
 
-void GPU_indexbuf_subbuilder_init(const GPUIndexBufBuilder *parent_builder,
-                                  GPUIndexBufBuilder *sub_builder)
+void GPU_indexbuf_join_copies(GPUIndexBufBuilder *builder_to,
+                              const GPUIndexBufBuilder *builder_from)
 {
-  BLI_assert(parent_builder->parent == nullptr);
-  memcpy(sub_builder, parent_builder, sizeof(GPUIndexBufBuilder));
-  sub_builder->parent = parent_builder;
-}
-
-void GPU_indexbuf_subbuilder_finish(GPUIndexBufBuilder *parent_builder,
-                                    const GPUIndexBufBuilder *sub_builder)
-{
-  BLI_assert(parent_builder == sub_builder->parent);
-  parent_builder->index_len = max_uu(parent_builder->index_len, sub_builder->index_len);
-  parent_builder->index_min = min_uu(parent_builder->index_min, sub_builder->index_min);
-  parent_builder->index_max = max_uu(parent_builder->index_max, sub_builder->index_max);
+  BLI_assert(builder_to->data == builder_from->data);
+  builder_to->index_len = max_uu(builder_to->index_len, builder_from->index_len);
+  builder_to->index_min = min_uu(builder_to->index_min, builder_from->index_min);
+  builder_to->index_max = max_uu(builder_to->index_max, builder_from->index_max);
 }
 
 void GPU_indexbuf_add_generic_vert(GPUIndexBufBuilder *builder, uint v)