Only calculate texture paint slots from mtex if renderer is blender

internal.

This should eliminate some confusion when people use external render
engines.

source/blender/blenkernel/BKE_material.h

@@ -86,8 +86,8 @@ short find_material_index(struct Object *ob, struct Material *ma);
 bool object_add_material_slot(struct Object *ob);
 bool object_remove_material_slot(struct Object *ob);
 
-void BKE_texpaint_slot_refresh_cache(struct Material *ma, bool use_nodes);
-void BKE_texpaint_slots_refresh_object(struct Object *ob, bool use_nodes);
+void BKE_texpaint_slot_refresh_cache(struct Scene *scene, struct Material *ma);
+void BKE_texpaint_slots_refresh_object(struct Scene *scene, struct Object *ob);
 void BKE_texpaint_slots_clear(struct Material *ma);
 
 /* rna api */

source/blender/blenkernel/BKE_scene.h

@@ -131,6 +131,7 @@ int get_render_shadow_samples(struct RenderData *r, int samples);
 float get_render_aosss_error(struct RenderData *r, float error);
 
 bool BKE_scene_use_new_shading_nodes(struct Scene *scene);
+bool BKE_scene_uses_blender_internal(struct Scene *scene);
 
 void BKE_scene_disable_color_management(struct Scene *scene);
 bool BKE_scene_check_color_management_enabled(const struct Scene *scene);

source/blender/blenkernel/intern/depsgraph.c

@@ -2497,11 +2497,10 @@ static void dag_id_flush_update(Main *bmain, Scene *sce, ID *id)
 		}
 
 		if (ELEM(idtype, ID_MA, ID_TE)) {
-			const bool new_shading_nodes = BKE_scene_use_new_shading_nodes(sce);
 			for (obt = bmain->object.first; obt; obt = obt->id.next) {
 				if (obt->mode & OB_MODE_TEXTURE_PAINT) {
 					obt->recalc |= OB_RECALC_DATA;
-					BKE_texpaint_slots_refresh_object(obt, new_shading_nodes);
+					BKE_texpaint_slots_refresh_object(sce, obt);
 					lib_id_recalc_data_tag(bmain, &obt->id);
 				}
 			}

source/blender/blenkernel/intern/material.c

@@ -63,6 +63,7 @@
 #include "BKE_main.h"
 #include "BKE_material.h"
 #include "BKE_mesh.h"
+#include "BKE_scene.h"
 #include "BKE_node.h"
 #include "BKE_curve.h"
 
@@ -1326,12 +1327,15 @@ static bool get_mtex_slot_valid_texpaint(struct MTex *mtex)
 	        mtex->tex->ima);
 }
 
-void BKE_texpaint_slot_refresh_cache(Material *ma, bool use_nodes)
+void BKE_texpaint_slot_refresh_cache(Scene *scene, Material *ma)
 {
 	MTex **mtex;
 	short count = 0;
 	short index = 0, i;
 
+	bool use_nodes = BKE_scene_use_new_shading_nodes(scene);
+	bool is_bi = BKE_scene_uses_blender_internal(scene);
+	
 	if (!ma)
 		return;
 
@@ -1340,10 +1344,10 @@ void BKE_texpaint_slot_refresh_cache(Material *ma, bool use_nodes)
 		ma->texpaintslot = NULL;
 	}
 
-	if (use_nodes) {
+	if (use_nodes || ma->use_nodes) {
 		bNode *node, *active_node;
 
-		if (!(ma->use_nodes && ma->nodetree))
+		if (!(ma->nodetree))
 			return;
 
 		for (node = ma->nodetree->nodes.first; node; node = node->next) {
@@ -1369,7 +1373,7 @@ void BKE_texpaint_slot_refresh_cache(Material *ma, bool use_nodes)
 			}
 		}
 	}
-	else {
+	else if (is_bi) {
 		for (mtex = ma->mtex, i = 0; i < MAX_MTEX; i++, mtex++) {
 			if (get_mtex_slot_valid_texpaint(*mtex)) {
 				count++;
@@ -1407,13 +1411,13 @@ void BKE_texpaint_slot_refresh_cache(Material *ma, bool use_nodes)
 	return;
 }
 
-void BKE_texpaint_slots_refresh_object(struct Object *ob, bool use_nodes)
+void BKE_texpaint_slots_refresh_object(Scene *scene, struct Object *ob)
 {
 	int i;
 
 	for (i = 1; i < ob->totcol + 1; i++) {
 		Material *ma = give_current_material(ob, i);
-		BKE_texpaint_slot_refresh_cache(ma, use_nodes);
+		BKE_texpaint_slot_refresh_cache(scene, ma);
 	}
 }
 

source/blender/blenkernel/intern/scene.c

@@ -1900,6 +1900,12 @@ bool BKE_scene_use_new_shading_nodes(Scene *scene)
 	return (type && type->flag & RE_USE_SHADING_NODES);
 }
 
+bool BKE_scene_uses_blender_internal(struct Scene *scene)
+{
+	return strcmp("BLENDER_INTERNAL", scene->r.engine);
+}
+
+
 void BKE_scene_base_flag_to_objects(struct Scene *scene)
 {
 	Base *base = scene->base.first;

source/blender/editors/sculpt_paint/paint_image.c

@@ -1445,10 +1445,9 @@ static int texture_paint_toggle_exec(bContext *C, wmOperator *op)
 		Main *bmain = CTX_data_main(C);
 		Material *ma;
 
-		bool use_nodes = BKE_scene_use_new_shading_nodes(scene);
 		/* This has to stay here to regenerate the texture paint
 		 * cache in case we are loading a file */
-		BKE_texpaint_slots_refresh_object(ob, use_nodes);
+		BKE_texpaint_slots_refresh_object(scene, ob);
 
 		paint_proj_mesh_data_ensure(C, ob, op);
 

source/blender/editors/sculpt_paint/paint_image_proj.c

@@ -4886,7 +4886,7 @@ bool proj_paint_add_slot(bContext *C, Material *ma, wmOperator *op)
 					ima = mtex->tex->ima = BKE_image_add_generated(bmain, width, height, imagename, alpha ? 32 : 24, use_float,
 					                                               gen_type, color);
 
-					BKE_texpaint_slot_refresh_cache(ma, false);
+					BKE_texpaint_slot_refresh_cache(scene, ma);
 					BKE_image_signal(ima, NULL, IMA_SIGNAL_USER_NEW_IMAGE);
 					WM_event_add_notifier(C, NC_TEXTURE | NA_ADDED, mtex->tex);
 					WM_event_add_notifier(C, NC_IMAGE | NA_ADDED, ima);
@@ -4993,7 +4993,7 @@ static int texture_paint_delete_texture_paint_slot_exec(bContext *C, wmOperator
 			MEM_freeN(ma->mtex[i]);
 			ma->mtex[i] = NULL;
 			
-			BKE_texpaint_slot_refresh_cache(ma, false);
+			BKE_texpaint_slot_refresh_cache(scene, ma);
 			DAG_id_tag_update(&ma->id, 0);
 			WM_event_add_notifier(C, NC_MATERIAL, CTX_data_scene(C));
 			/* we need a notifier for data change since we change the displayed modifier uvs */