Blender: Add command line argument to switch gpu backends.

Add command line argument to switch gpu backend. Add `--gpu-backend` option to
override the gpu backend selected by Blender.

Values for this option that will be available in releases for now are:
* opengl: Force blender to select OpenGL backend.

During development and depending on compile options additional values can exist:
* metal: Force Blender to select Metal backend.

When this option isn't provided the internal logic for GPU backend selection will be used.
Note that this is at the time of writing the same as always selecting the opengl backend.

Reviewed By: fclem, brecht, MichaelPW

Differential Revision: https://developer.blender.org/D16297

1 files changed, 9 insertions, 0 deletions

diff --git a/source/blender/gpu/intern/gpu_shader_builder_stubs.cc b/source/blender/gpu/intern/gpu_shader_builder_stubs.cc
index 7a06ede5c6d..65bda7ba858 100644
--- a/source/blender/gpu/intern/gpu_shader_builder_stubs.cc
+++ b/source/blender/gpu/intern/gpu_shader_builder_stubs.cc
@@ -46,6 +46,15 @@ void IMB_freeImBuf(ImBuf * /*ibuf*/)
   BLI_assert_unreachable();
 }
 
+struct ImBuf *IMB_allocImBuf(unsigned int /*x*/,
+                             unsigned int /*y*/,
+                             unsigned char /*planes*/,
+                             unsigned int /*flags*/)
+{
+  BLI_assert_unreachable();
+  return nullptr;
+}
+
 /** \} */
 
 /* -------------------------------------------------------------------- */