Fix T62101: GPencil: selection order is wrong

Following the advices of @Germano Cavalcante (mano-wii) , I have exposed as a workaround the free function to be called from draw manager for selection.

Now, the free function is not called for selection inside gpencil draw_scene, but it's called from draw_manager.c.

The real fix would be create a new Scene_finish callback in draw manager, but as the release of 2.80 is almost here, we fix this with a workaround that must be removed when new callback is in place.

Differential Revision: http://developer.blender.org/D5193

source/blender/draw/engines/gpencil/gpencil_engine.c

@@ -771,8 +771,11 @@ static void gpencil_prepare_fast_drawing(GPENCIL_StorageList *stl,
   }
 }
 
-static void gpencil_free_runtime_data(GPENCIL_StorageList *stl)
+void DRW_gpencil_free_runtime_data(void *ved)
 {
+  GPENCIL_Data *vedata = (GPENCIL_Data *)ved;
+  GPENCIL_StorageList *stl = ((GPENCIL_Data *)vedata)->stl;
+
   /* free gpu data */
   DRW_TEXTURE_FREE_SAFE(stl->g_data->gpencil_blank_texture);
 
@@ -976,8 +979,6 @@ void GPENCIL_draw_scene(void *ved)
   /* if the draw is for select, do a basic drawing and return */
   if (DRW_state_is_select() || DRW_state_is_depth()) {
     drw_gpencil_select_render(stl, psl);
-    /* free memory */
-    gpencil_free_runtime_data(stl);
     return;
   }
 
@@ -1010,7 +1011,7 @@ void GPENCIL_draw_scene(void *ved)
     }
 
     /* free memory */
-    gpencil_free_runtime_data(stl);
+    DRW_gpencil_free_runtime_data(ved);
 
     return;
   }
@@ -1159,7 +1160,7 @@ void GPENCIL_draw_scene(void *ved)
     }
   }
   /* free memory */
-  gpencil_free_runtime_data(stl);
+  DRW_gpencil_free_runtime_data(ved);
 
   /* reset  */
   if (DRW_state_is_fbo()) {

source/blender/draw/engines/gpencil/gpencil_engine.h

@@ -359,12 +359,12 @@ typedef struct GpencilBatchCacheElem {
 } GpencilBatchCacheElem;
 
 typedef struct GpencilBatchGroup {
-  bGPDlayer *gpl;  /* reference to original layer */
-  bGPDframe *gpf;  /* reference to original frame */
-  bGPDstroke *gps; /* reference to original stroke */
-  short type;      /* type of element */
-  bool onion;      /* the group is part of onion skin */
-  int vertex_idx;  /* index of vertex data */
+  struct bGPDlayer *gpl;  /* reference to original layer */
+  struct bGPDframe *gpf;  /* reference to original frame */
+  struct bGPDstroke *gps; /* reference to original stroke */
+  short type;             /* type of element */
+  bool onion;             /* the group is part of onion skin */
+  int vertex_idx;         /* index of vertex data */
 } GpencilBatchGroup;
 
 typedef enum GpencilBatchGroup_Type {
@@ -507,6 +507,10 @@ void GPENCIL_render_to_image(void *vedata,
                              struct RenderLayer *render_layer,
                              const rcti *rect);
 
+/* TODO: GPXX workaround function to call free memory from draw manager while draw manager support
+ * scene finish callback. */
+void DRW_gpencil_free_runtime_data(void *ved);
+
 /* Use of multisample framebuffers. */
 #define MULTISAMPLE_GP_SYNC_ENABLE(lvl, fbl) \
   { \

source/blender/draw/intern/draw_manager.c

@@ -88,6 +88,7 @@
 #include "engines/basic/basic_engine.h"
 #include "engines/workbench/workbench_engine.h"
 #include "engines/external/external_engine.h"
+#include "engines/gpencil/gpencil_engine.h"
 
 #include "GPU_context.h"
 
@@ -2379,6 +2380,13 @@ void DRW_draw_select_loop(struct Depsgraph *depsgraph,
     }
   }
 
+  /* TODO: GPXX Workaround for grease pencil selection while draw manager support a callback from
+   * scene finish */
+  void *data = GPU_viewport_engine_data_get(DST.viewport, &draw_engine_gpencil_type);
+  if (data != NULL) {
+    DRW_gpencil_free_runtime_data(data);
+  }
+
   DRW_state_lock(0);
 
   DRW_draw_callbacks_post_scene();