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.

2 files changed, 9 insertions, 5 deletions

diff --git a/source/blender/gpu/opengl/gl_debug.cc b/source/blender/gpu/opengl/gl_debug.cc
index 797f9ff404c..b2b05124463 100644
--- a/source/blender/gpu/opengl/gl_debug.cc
+++ b/source/blender/gpu/opengl/gl_debug.cc
@@ -200,7 +200,7 @@ void check_gl_error(const char *info)
 
 void check_gl_resources(const char *info)
 {
-  if (!(G.debug & G_DEBUG_GPU)) {
+  if (!(G.debug & G_DEBUG_GPU) || GPU_bgl_get()) {
     return;
   }
 
diff --git a/source/blender/gpu/opengl/gl_state.cc b/source/blender/gpu/opengl/gl_state.cc
index cd24fa0e0e4..27c9b501add 100644
--- a/source/blender/gpu/opengl/gl_state.cc
+++ b/source/blender/gpu/opengl/gl_state.cc
@@ -73,13 +73,17 @@ GLStateManager::GLStateManager(void) : StateManager()
 
 void GLStateManager::apply_state(void)
 {
-  this->set_state(this->state);
-  this->set_mutable_state(this->mutable_state);
-  this->texture_bind_apply();
-  this->image_bind_apply();
+  if (!this->use_bgl) {
+    this->set_state(this->state);
+    this->set_mutable_state(this->mutable_state);
+    this->texture_bind_apply();
+    this->image_bind_apply();
+  }
+  /* This is needed by gpu_py_offscreen. */
   active_fb->apply_state();
 };
 
+/* Will set all the states regardless of the current ones. */
 void GLStateManager::force_state(void)
 {
   /* Little exception for clip distances since they need to keep the old count correct. */