Fix T40646: Knife project fails with clipping

1 files changed, 18 insertions, 7 deletions

diff --git a/source/blender/editors/mesh/editmesh_knife.c b/source/blender/editors/mesh/editmesh_knife.c
index 8be8c415be2..96a608a432b 100644
--- a/source/blender/editors/mesh/editmesh_knife.c
+++ b/source/blender/editors/mesh/editmesh_knife.c
@@ -1161,6 +1161,13 @@ static bool point_is_visible(KnifeTool_OpData *kcd, const float p[3], const floa
 {
 	BMFace *f_hit;
 
+	/* If box clipping on, make sure p is not clipped */
+	if (kcd->vc.rv3d->rflag & RV3D_CLIPPING &&
+	    ED_view3d_clipping_test(kcd->vc.rv3d, p, true))
+	{
+		return false;
+	}
+
 	/* If not cutting through, make sure no face is in front of p */
 	if (!kcd->cut_through) {
 		float dist;
@@ -1181,19 +1188,23 @@ static bool point_is_visible(KnifeTool_OpData *kcd, const float p[3], const floa
 			dist = kcd->vc.v3d->far * 2.0f;
 		}
 
+		if (kcd->vc.rv3d->rflag & RV3D_CLIPPING) {
+			float view_clip[2][3];
+			/* note: view_clip[0] should never get clipped */
+			copy_v3_v3(view_clip[0], p_ofs);
+			madd_v3_v3v3fl(view_clip[1], p_ofs, view, dist);
+
+			if (clip_segment_v3_plane_n(view_clip[0], view_clip[1], kcd->vc.rv3d->clip_local, 6)) {
+				dist = len_v3v3(p_ofs, view_clip[1]);
+			}
+		}
+
 		/* see if there's a face hit between p1 and the view */
 		f_hit = BKE_bmbvh_ray_cast(kcd->bmbvh, p_ofs, view, KNIFE_FLT_EPS, &dist, NULL, NULL);
 		if (f_hit)
 			return false;
 	}
 
-	/* If box clipping on, make sure p is not clipped */
-	if (kcd->vc.rv3d->rflag & RV3D_CLIPPING &&
-	    ED_view3d_clipping_test(kcd->vc.rv3d, p, true))
-	{
-		return false;
-	}
-
 	return true;
 }