1 files changed, 41 insertions, 3 deletions

diff --git a/source/blender/editors/sculpt_paint/paint_image_proj.c b/source/blender/editors/sculpt_paint/paint_image_proj.c
index a24ee13e3bf..553a5cbe9ac 100644
--- a/source/blender/editors/sculpt_paint/paint_image_proj.c
+++ b/source/blender/editors/sculpt_paint/paint_image_proj.c
@@ -1121,6 +1121,44 @@ static void screen_px_from_persp(
 	interp_v3_v3v3v3(pixelScreenCo, v1co, v2co, v3co, w);
 }
 
+
+/* same as screen_px_from_persp except we return ortho weights back to the caller.
+ * These weights will be used to determine correct interpolation of uvs in cloned uv layer */
+static void screen_px_from_persp_ortho_weights(
+        float uv[2],
+        float v1co[4], float v2co[4], float v3co[4],  /* screenspace coords */
+        float uv1co[2], float uv2co[2], float uv3co[2],
+        float pixelScreenCo[4],
+        float w[3])
+{
+	float w_int[3];
+	float wtot_inv, wtot;
+	barycentric_weights_v2(uv1co, uv2co, uv3co, uv, w);
+
+	/* re-weight from the 4th coord of each screen vert */
+	w_int[0] = w[0] * v1co[3];
+	w_int[1] = w[1] * v2co[3];
+	w_int[2] = w[2] * v3co[3];
+
+	wtot = w_int[0] + w_int[1] + w_int[2];
+
+	if (wtot > 0.0f) {
+		wtot_inv = 1.0f / wtot;
+		w_int[0] *= wtot_inv;
+		w_int[1] *= wtot_inv;
+		w_int[2] *= wtot_inv;
+	}
+	else {
+		w[0] = w[1] = w[2] =
+		w_int[0] = w_int[1] = w_int[2] = 1.0f / 3.0f;  /* dummy values for zero area face */
+	}
+	/* done re-weighting */
+
+	/* do interpolation based on projected weight */
+	interp_v3_v3v3v3(pixelScreenCo, v1co, v2co, v3co, w_int);
+}
+
+
 static void project_face_pixel(const MTFace *tf_other, ImBuf *ibuf_other, const float w[3],
                                int side, unsigned char rgba_ub[4], float rgba_f[4])
 {
@@ -2168,6 +2206,7 @@ static void project_paint_face_init(const ProjPaintState *ps, const int thread_i
 	float uv_clip[8][2];
 	int uv_clip_tot;
 	const short is_ortho = ps->is_ortho;
+	const short is_clone_other = ((ps->brush->imagepaint_tool == PAINT_TOOL_CLONE) && ps->dm_mtface_clone);
 	const short do_backfacecull = ps->do_backfacecull;
 	const short do_clip = ps->rv3d ? ps->rv3d->rflag & RV3D_CLIPPING : 0;
 
@@ -2191,8 +2230,6 @@ static void project_paint_face_init(const ProjPaintState *ps, const int thread_i
 	 * but since the first thing most people try is painting onto a quad- better make it work.
 	 */
 
-
-
 	tf_uv_pxoffset[0][0] = tf->uv[0][0] - xhalfpx;
 	tf_uv_pxoffset[0][1] = tf->uv[0][1] - yhalfpx;
 
@@ -2277,7 +2314,8 @@ static void project_paint_face_init(const ProjPaintState *ps, const int thread_i
 						has_x_isect = has_isect = 1;
 
 						if (is_ortho) screen_px_from_ortho(uv, v1coSS, v2coSS, v3coSS, uv1co, uv2co, uv3co, pixelScreenCo, w);
-						else          screen_px_from_persp(uv, v1coSS, v2coSS, v3coSS, uv1co, uv2co, uv3co, pixelScreenCo, w);
+						else if (is_clone_other) screen_px_from_persp_ortho_weights(uv, v1coSS, v2coSS, v3coSS, uv1co, uv2co, uv3co, pixelScreenCo, w);
+						else screen_px_from_persp(uv, v1coSS, v2coSS, v3coSS, uv1co, uv2co, uv3co, pixelScreenCo, w);
 
 						/* a pity we need to get the worldspace pixel location here */
 						if (do_clip || do_3d_mapping) {