Fix issue discovered in soc-paint-2013 branch.

Weights do not need perspective correction since they are calculated on
flat triangle coordinates. Only pixel coordinates, reprojected from the
weights need this.

This was already fixed for clone brushes but in
soc-2013-paint where we have stencil preview, it is apparent that the
stencil suffered from the perspective distortion issue too.

1 files changed, 2 insertions, 39 deletions

diff --git a/source/blender/editors/sculpt_paint/paint_image_proj.c b/source/blender/editors/sculpt_paint/paint_image_proj.c
index 86a4de9d985..e691ecdc006 100644
--- a/source/blender/editors/sculpt_paint/paint_image_proj.c
+++ b/source/blender/editors/sculpt_paint/paint_image_proj.c
@@ -1063,8 +1063,8 @@ static void screen_px_from_ortho(
 	interp_v3_v3v3v3(pixelScreenCo, v1co, v2co, v3co, w);
 }
 
-/* same as screen_px_from_ortho except we need to take into account
- * the perspective W coord for each vert */
+/* same as screen_px_from_ortho except we
+ * do perspective correction on the pixel coordinate */
 static void screen_px_from_persp(
         const float uv[2],
         const float v1co[4], const float v2co[4], const float v3co[4],  /* screenspace coords */
@@ -1072,41 +1072,6 @@ static void screen_px_from_persp(
         float pixelScreenCo[4],
         float w[3])
 {
-
-	float wtot_inv, wtot;
-	barycentric_weights_v2(uv1co, uv2co, uv3co, uv, w);
-
-	/* re-weight from the 4th coord of each screen vert */
-	w[0] *= v1co[3];
-	w[1] *= v2co[3];
-	w[2] *= v3co[3];
-
-	wtot = w[0] + w[1] + w[2];
-
-	if (wtot > 0.0f) {
-		wtot_inv = 1.0f / wtot;
-		w[0] *= wtot_inv;
-		w[1] *= wtot_inv;
-		w[2] *= wtot_inv;
-	}
-	else {
-		w[0] = w[1] = w[2] = 1.0f / 3.0f;  /* dummy values for zero area face */
-	}
-	/* done re-weighting */
-
-	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(
-        const float uv[2],
-        const float v1co[4], const float v2co[4], const float v3co[4],  /* screenspace coords */
-        const float uv1co[2], const float uv2co[2], const 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);
@@ -2183,7 +2148,6 @@ static void project_paint_face_init(const ProjPaintState *ps, const int thread_i
 	float uv_clip[8][2];
 	int uv_clip_tot;
 	const bool is_ortho = ps->is_ortho;
-	const bool is_clone_other = ((ps->brush->imagepaint_tool == PAINT_TOOL_CLONE) && ps->dm_mtface_clone);
 	const bool do_backfacecull = ps->do_backfacecull;
 	const bool do_clip = ps->rv3d ? ps->rv3d->rflag & RV3D_CLIPPING : 0;
 
@@ -2291,7 +2255,6 @@ 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 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 */