Fix T77830: Crash in VR session when opening material preview

Draw-manager mutex has to be set before activating OpenGL/GPU context.
Otherwise, parallel jobs (like preview rendering) may try to activate
the context from another thread.

Also: Use WM wrappers for activating/releasing OpenGL context, which
have an additional assert check.

Suggest to backport this for 2.83.1.

1 files changed, 3 insertions, 3 deletions

diff --git a/source/blender/windowmanager/xr/intern/wm_xr_session.c b/source/blender/windowmanager/xr/intern/wm_xr_session.c
index e9ff38c5a92..2f72b2b25a5 100644
--- a/source/blender/windowmanager/xr/intern/wm_xr_session.c
+++ b/source/blender/windowmanager/xr/intern/wm_xr_session.c
@@ -315,12 +315,9 @@ static void wm_xr_session_surface_draw(bContext *C)
   wm_xr_session_draw_data_populate(
       &wm->xr, CTX_data_scene(C), CTX_data_ensure_evaluated_depsgraph(C), &draw_data);
 
-  DRW_xr_drawing_begin();
-
   GHOST_XrSessionDrawViews(wm->xr.runtime->context, &draw_data);
 
   GPU_offscreen_unbind(surface_data->offscreen, false);
-  DRW_xr_drawing_end();
 }
 
 bool wm_xr_session_surface_offscreen_ensure(wmXrSurfaceData *surface_data,
@@ -391,6 +388,9 @@ static wmSurface *wm_xr_session_surface_create(void)
 
   surface->draw = wm_xr_session_surface_draw;
   surface->free_data = wm_xr_session_surface_free_data;
+  surface->activate = DRW_xr_drawing_begin;
+  surface->deactivate = DRW_xr_drawing_end;
+
   surface->ghost_ctx = DRW_xr_opengl_context_get();
   surface->gpu_ctx = DRW_xr_gpu_context_get();