GPUStorageBuf: Add `GPU_storagebuf_copy_sub_from_vertbuf()`

This allows using the Graphic API to copy buffer data.
The GPU module do not expose untyped buffers even if that's what most API
do, so the copy function need to be strongly typed.

Contains GL backend implementation.

1 files changed, 24 insertions, 0 deletions

diff --git a/source/blender/gpu/opengl/gl_storage_buffer.cc b/source/blender/gpu/opengl/gl_storage_buffer.cc
index 109bb65fcb7..b30674fe5fa 100644
--- a/source/blender/gpu/opengl/gl_storage_buffer.cc
+++ b/source/blender/gpu/opengl/gl_storage_buffer.cc
@@ -144,6 +144,30 @@ void GLStorageBuf::clear(eGPUTextureFormat internal_format, eGPUDataFormat data_
   }
 }
 
+void GLStorageBuf::copy_sub(VertBuf *src_, uint dst_offset, uint src_offset, uint copy_size)
+{
+  GLVertBuf *src = static_cast<GLVertBuf *>(src_);
+  GLStorageBuf *dst = this;
+
+  if (dst->ssbo_id_ == 0) {
+    dst->init();
+  }
+  if (src->vbo_id_ == 0) {
+    src->bind();
+  }
+
+  if (GLContext::direct_state_access_support) {
+    glCopyNamedBufferSubData(src->vbo_id_, dst->ssbo_id_, src_offset, dst_offset, copy_size);
+  }
+  else {
+    /* This binds the buffer to GL_ARRAY_BUFFER and upload the data if any. */
+    src->bind();
+    glBindBuffer(GL_COPY_WRITE_BUFFER, dst->ssbo_id_);
+    glCopyBufferSubData(GL_ARRAY_BUFFER, GL_COPY_WRITE_BUFFER, src_offset, dst_offset, copy_size);
+    glBindBuffer(GL_COPY_WRITE_BUFFER, 0);
+  }
+}
+
 /** \} */
 
 }  // namespace blender::gpu