Fix visible seams on normal map bake due to clear colour being black:

 This is a special case, tangent space normal maps should be cleared to
0.5, 0.5, 1.0. This is good practice but there's no reason why not to
automate this (for artists whose bump map fu may be a bit shallow).

Thanks to Morten Mikkelsen for reporting.

2 files changed, 29 insertions, 7 deletions

diff --git a/source/blender/editors/object/object_bake.c b/source/blender/editors/object/object_bake.c
index 322ba99593e..a680230fb32 100644
--- a/source/blender/editors/object/object_bake.c
+++ b/source/blender/editors/object/object_bake.c
@@ -257,11 +257,18 @@ static DerivedMesh *multiresbake_create_hiresdm(Scene *scene, Object *ob, int *l
 	return dm;
 }
 
-static void clear_images(MTFace *mtface, int totface)
+typedef enum ClearFlag {
+	CLEAR_NORMAL = 1
+} ClearFlag;
+
+
+static void clear_images(MTFace *mtface, int totface, ClearFlag flag)
 {
 	int a;
 	const float vec_alpha[4] = {0.0f, 0.0f, 0.0f, 0.0f};
 	const float vec_solid[4] = {0.0f, 0.0f, 0.0f, 1.0f};
+	const float nor_alpha[4] = {0.5f, 0.5f, 1.0f, 0.0f};
+	const float nor_solid[4] = {0.5f, 0.5f, 1.0f, 1.0f};
 
 	for (a = 0; a < totface; a++)
 		mtface[a].tpage->id.flag &= ~LIB_DOIT;
@@ -272,7 +279,11 @@ static void clear_images(MTFace *mtface, int totface)
 		if ((ima->id.flag & LIB_DOIT) == 0) {
 			ImBuf *ibuf = BKE_image_acquire_ibuf(ima, NULL, NULL);
 
-			IMB_rectfill(ibuf, (ibuf->planes == R_IMF_PLANES_RGBA) ? vec_alpha : vec_solid);
+			if (flag == CLEAR_NORMAL)
+				IMB_rectfill(ibuf, (ibuf->planes == R_IMF_PLANES_RGBA) ? nor_alpha : nor_solid);
+			else
+				IMB_rectfill(ibuf, (ibuf->planes == R_IMF_PLANES_RGBA) ? vec_alpha : vec_solid);
+
 			ima->id.flag |= LIB_DOIT;
 
 			BKE_image_release_ibuf(ima, ibuf, NULL);
@@ -300,7 +311,10 @@ static int multiresbake_image_exec_locked(bContext *C, wmOperator *op)
 			ob = base->object;
 			me = (Mesh *)ob->data;
 
-			clear_images(me->mtface, me->totface);
+			if (scene->r.bake_mode == RE_BAKE_NORMALS && scene->r.bake_normal_space == R_BAKE_SPACE_TANGENT)
+				clear_images(me->mtface, me->totface, CLEAR_NORMAL);
+			else
+				clear_images(me->mtface, me->totface, 0);
 		}
 		CTX_DATA_END;
 	}
@@ -395,7 +409,10 @@ static void multiresbake_startjob(void *bkv, short *stop, short *do_update, floa
 			DerivedMesh *dm = data->lores_dm;
 			MTFace *mtface = CustomData_get_layer(&dm->faceData, CD_MTFACE);
 
-			clear_images(mtface, dm->getNumTessFaces(dm));
+			if (bkj->mode == RE_BAKE_NORMALS)
+				clear_images(mtface, dm->getNumTessFaces(dm), CLEAR_NORMAL);
+			else
+				clear_images(mtface, dm->getNumTessFaces(dm), 0);
 		}
 	}
 
diff --git a/source/blender/render/intern/source/bake.c b/source/blender/render/intern/source/bake.c
index cb6f9611bfd..7c5d6038e0a 100644
--- a/source/blender/render/intern/source/bake.c
+++ b/source/blender/render/intern/source/bake.c
@@ -648,6 +648,8 @@ static int get_next_bake_face(BakeShade *bs)
 					ImBuf *ibuf = NULL;
 					const float vec_alpha[4] = {0.0f, 0.0f, 0.0f, 0.0f};
 					const float vec_solid[4] = {0.0f, 0.0f, 0.0f, 1.0f};
+					const float nor_alpha[4] = {0.5f, 0.5f, 1.0f, 0.0f};
+					const float nor_solid[4] = {0.5f, 0.5f, 1.0f, 1.0f};
 
 					tface = RE_vlakren_get_tface(obr, vlr, obr->bakemtface, NULL, 0);
 
@@ -684,9 +686,12 @@ static int get_next_bake_face(BakeShade *bs)
 						if (ibuf->rect_float)
 							imb_freerectImBuf(ibuf);
 						/* clear image */
-						if (R.r.bake_flag & R_BAKE_CLEAR)
-							IMB_rectfill(ibuf, (ibuf->planes == R_IMF_PLANES_RGBA) ? vec_alpha : vec_solid);
-
+						if (R.r.bake_flag & R_BAKE_CLEAR) {
+							if (R.r.bake_mode == RE_BAKE_NORMALS && R.r.bake_normal_space == R_BAKE_SPACE_TANGENT)
+								IMB_rectfill(ibuf, (ibuf->planes == R_IMF_PLANES_RGBA) ? nor_alpha : nor_solid);
+							else
+								IMB_rectfill(ibuf, (ibuf->planes == R_IMF_PLANES_RGBA) ? vec_alpha : vec_solid);
+						}
 						/* might be read by UI to set active image for display */
 						R.bakebuf = ima;
 					}