From 64927349ec1ba59fcdc3dba3c6b7fb18e8478e7d Mon Sep 17 00:00:00 2001
From: Dalai Felinto <dalai@blender.org>
Date: Tue, 17 Oct 2023 11:55:14 +0200
Subject: [PATCH 1/2] GPv3: Replace Material node

Note: At the moment the node only supports non-Grease Pencil materials.
But if the material socket is connected to the modifier a Grease Pencil
material can be used.

Part of #113602.
---
 .../nodes/geometry/nodes/node_geo_material_replace.cc | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/source/blender/nodes/geometry/nodes/node_geo_material_replace.cc b/source/blender/nodes/geometry/nodes/node_geo_material_replace.cc
index 03f6cbed68f..eafabc5b15c 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_material_replace.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_material_replace.cc
@@ -10,13 +10,15 @@
 #include "DNA_mesh_types.h"
 #include "DNA_meshdata_types.h"
 
+#include "BKE_grease_pencil.hh"
 #include "BKE_material.h"
 
 namespace blender::nodes::node_geo_material_replace_cc {
 
 static void node_declare(NodeDeclarationBuilder &b)
 {
-  b.add_input<decl::Geometry>("Geometry").supported_type(GeometryComponent::Type::Mesh);
+  b.add_input<decl::Geometry>("Geometry")
+      .supported_type({GeometryComponent::Type::Mesh, GeometryComponent::Type::GreasePencil});
   b.add_input<decl::Material>("Old");
   b.add_input<decl::Material>("New").translation_context(BLT_I18NCONTEXT_ID_MATERIAL);
   b.add_output<decl::Geometry>("Geometry").propagate_all();
@@ -37,6 +39,13 @@ static void node_geo_exec(GeoNodeExecParams params)
         }
       }
     }
+    if (GreasePencil *grease_pencil = geometry_set.get_grease_pencil_for_write()) {
+      for (const int i : IndexRange(grease_pencil->material_array_num)) {
+        if (grease_pencil->material_array[i] == old_material) {
+          grease_pencil->material_array[i] = new_material;
+        }
+      }
+    }
   });
 
   params.set_output("Geometry", std::move(geometry_set));
-- 
2.30.2


From 379c28c6afdf5b8fe3b349f25ead3b2f4a365bbc Mon Sep 17 00:00:00 2001
From: Hans Goudey <hans@blender.org>
Date: Tue, 17 Oct 2023 18:49:07 +0200
Subject: [PATCH 2/2] From review: deduplicate code

---
 .../nodes/node_geo_material_replace.cc        | 25 +++++++++++--------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/source/blender/nodes/geometry/nodes/node_geo_material_replace.cc b/source/blender/nodes/geometry/nodes/node_geo_material_replace.cc
index eafabc5b15c..ad238c4110e 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_material_replace.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_material_replace.cc
@@ -24,6 +24,17 @@ static void node_declare(NodeDeclarationBuilder &b)
   b.add_output<decl::Geometry>("Geometry").propagate_all();
 }
 
+static void replace_materials(MutableSpan<Material *> materials,
+                              Material *src_material,
+                              Material *dst_material)
+{
+  for (const int i : materials.index_range()) {
+    if (materials[i] == src_material) {
+      materials[i] = dst_material;
+    }
+  }
+}
+
 static void node_geo_exec(GeoNodeExecParams params)
 {
   Material *old_material = params.extract_input<Material *>("Old");
@@ -33,18 +44,12 @@ static void node_geo_exec(GeoNodeExecParams params)
 
   geometry_set.modify_geometry_sets([&](GeometrySet &geometry_set) {
     if (Mesh *mesh = geometry_set.get_mesh_for_write()) {
-      for (const int i : IndexRange(mesh->totcol)) {
-        if (mesh->mat[i] == old_material) {
-          mesh->mat[i] = new_material;
-        }
-      }
+      replace_materials({mesh->mat, mesh->totcol}, old_material, new_material);
     }
     if (GreasePencil *grease_pencil = geometry_set.get_grease_pencil_for_write()) {
-      for (const int i : IndexRange(grease_pencil->material_array_num)) {
-        if (grease_pencil->material_array[i] == old_material) {
-          grease_pencil->material_array[i] = new_material;
-        }
-      }
+      replace_materials({grease_pencil->material_array, grease_pencil->material_array_num},
+                        old_material,
+                        new_material);
     }
   });
 
-- 
2.30.2