BGL: Workaround broken bgl usage caused by GPU refactor

This directly adress the issues caused by rB536c2e0ec916.

Since the state tracking is done at a lower level, using the bgl
functions needs to be safegarded by the state manager.
The current workaround is to bypass `apply_state` when inside a
callback that used a `bgl` function.

Related to T80730.

This fix T81003.

Also this fix the default blend equation for callbacks.
Fixes T80169 T81289.

1 files changed, 4 insertions, 1 deletions

diff --git a/source/blender/gpu/GPU_state.h b/source/blender/gpu/GPU_state.h
index 04cf7bc54ba..471edfb7b8f 100644
--- a/source/blender/gpu/GPU_state.h
+++ b/source/blender/gpu/GPU_state.h
@@ -161,7 +161,10 @@ float GPU_line_width_get(void);
 void GPU_flush(void);
 void GPU_finish(void);
 void GPU_apply_state(void);
-void GPU_force_state(void);
+
+void GPU_bgl_start(void);
+void GPU_bgl_end(void);
+bool GPU_bgl_get(void);
 
 void GPU_memory_barrier(eGPUBarrier barrier);