Fix T46508: data_transfer of normals fails in case objects are transformed.

The final stage of the process (copying/interpolating new dst cddata from src cddata)
was simply broken in normal case, where we need to convert from source to destination
object space.

This patch is a bit verbose, but I cannot see how to avoid it really.

To think this code is in master since over 6 months and it only gets reported now... :/

1 files changed, 34 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/customdata.c b/source/blender/blenkernel/intern/customdata.c
index f14feee0b2a..7149b24161f 100644
--- a/source/blender/blenkernel/intern/customdata.c
+++ b/source/blender/blenkernel/intern/customdata.c
@@ -61,6 +61,8 @@
 #include "BKE_mesh_remap.h"
 #include "BKE_multires.h"
 
+#include "data_transfer_intern.h"
+
 #include "bmesh.h"
 
 #include <math.h>
@@ -3913,6 +3915,38 @@ static void customdata_data_transfer_interp_generic(
 	MEM_freeN(tmp_dst);
 }
 
+/* Normals are special, we need to take care of source & destination spaces... */
+void customdata_data_transfer_interp_normal_normals(
+        const CustomDataTransferLayerMap *laymap, void *data_dst,
+        const void **sources, const float *weights, const int count,
+        const float mix_factor)
+{
+	const int data_type = laymap->data_type;
+	const int mix_mode = laymap->mix_mode;
+
+	SpaceTransform *space_transform = laymap->interp_data;
+
+	const LayerTypeInfo *type_info = layerType_getInfo(data_type);
+	cd_interp interp_cd = type_info->interp;
+
+	float tmp_dst[3];
+
+	BLI_assert(data_type == CD_NORMAL);
+
+	if (!sources) {
+		/* Not supported here, abort. */
+		return;
+	}
+
+	interp_cd(sources, weights, NULL, count, tmp_dst);
+	if (space_transform) {
+		/* tmp_dst is in source space so far, bring it back in destination space. */
+		BLI_space_transform_invert_normal(space_transform, tmp_dst);
+	}
+
+	CustomData_data_mix_value(data_type, tmp_dst, data_dst, mix_mode, mix_factor);
+}
+
 void CustomData_data_transfer(const MeshPairRemap *me_remap, const CustomDataTransferLayerMap *laymap)
 {
 	MeshPairRemapItem *mapit = me_remap->items;