From e0d1e66732156e01797dc2f1b7ce9fb507834903 Mon Sep 17 00:00:00 2001
From: Antonio Vazquez <blendergit@gmail.com>
Date: Thu, 30 Dec 2021 12:48:51 +0100
Subject: Fix T93868: GPencil material filter does not work with instances

When the material is used in several objects, the filter by material is not working as expected because the internal pointers are different due eval version.

Now, the original version of the material is compared to keep same address.
---
 .../blender/gpencil_modifiers/intern/MOD_gpencil_util.c   | 15 ++++++++++-----
 .../blender/gpencil_modifiers/intern/MOD_gpencil_util.h   |  2 +-
 2 files changed, 11 insertions(+), 6 deletions(-)

(limited to 'source')

diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencil_util.c b/source/blender/gpencil_modifiers/intern/MOD_gpencil_util.c
index f6a85919de4..c583a45a27d 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencil_util.c
+++ b/source/blender/gpencil_modifiers/intern/MOD_gpencil_util.c
@@ -40,6 +40,8 @@
 #include "MOD_gpencil_modifiertypes.h"
 #include "MOD_gpencil_util.h"
 
+#include "DEG_depsgraph_query.h"
+
 void gpencil_modifier_type_init(GpencilModifierTypeInfo *types[])
 {
 #define INIT_GP_TYPE(typeName) \
@@ -73,7 +75,7 @@ void gpencil_modifier_type_init(GpencilModifierTypeInfo *types[])
 
 bool is_stroke_affected_by_modifier(Object *ob,
                                     char *mlayername,
-                                    const Material *material,
+                                    Material *material,
                                     const int mpassindex,
                                     const int gpl_passindex,
                                     const int minpoints,
@@ -84,8 +86,8 @@ bool is_stroke_affected_by_modifier(Object *ob,
                                     const bool inv3,
                                     const bool inv4)
 {
-  Material *ma = BKE_gpencil_material(ob, gps->mat_nr + 1);
-  MaterialGPencilStyle *gp_style = ma->gp_style;
+  Material *ma_gps = BKE_gpencil_material(ob, gps->mat_nr + 1);
+  MaterialGPencilStyle *gp_style = ma_gps->gp_style;
 
   /* omit if filter by layer */
   if (mlayername[0] != '\0') {
@@ -102,13 +104,16 @@ bool is_stroke_affected_by_modifier(Object *ob,
   }
   /* Omit if filter by material. */
   if (material != NULL) {
+    /* Requires to use the original material to compare the same pointer address. */
+    Material *ma_md_orig = (Material *)DEG_get_original_id(&material->id);
+    Material *ma_gps_orig = (Material *)DEG_get_original_id(&ma_gps->id);
     if (inv4 == false) {
-      if (material != ma) {
+      if (ma_md_orig != ma_gps_orig) {
         return false;
       }
     }
     else {
-      if (material == ma) {
+      if (ma_md_orig == ma_gps_orig) {
         return false;
       }
     }
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencil_util.h b/source/blender/gpencil_modifiers/intern/MOD_gpencil_util.h
index 59ed11a02f3..722574929c0 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencil_util.h
+++ b/source/blender/gpencil_modifiers/intern/MOD_gpencil_util.h
@@ -34,7 +34,7 @@ struct bGPDstroke;
  */
 bool is_stroke_affected_by_modifier(struct Object *ob,
                                     char *mlayername,
-                                    const struct Material *material,
+                                    struct Material *material,
                                     const int mpassindex,
                                     const int gpl_passindex,
                                     const int minpoints,
-- 
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