Fix T57045: Unhandled degenerate case in bevel code

Reviewers: howardt

Differential Revision: https://developer.blender.org/D4104

1 files changed, 27 insertions, 22 deletions

diff --git a/source/blender/bmesh/tools/bmesh_bevel.c b/source/blender/bmesh/tools/bmesh_bevel.c
index 8499db2fdb5..f0c2a343d4a 100644
--- a/source/blender/bmesh/tools/bmesh_bevel.c
+++ b/source/blender/bmesh/tools/bmesh_bevel.c
@@ -1261,31 +1261,36 @@ static bool make_unit_square_map(
 
 	sub_v3_v3v3(va_vmid, vmid, va);
 	sub_v3_v3v3(vb_vmid, vmid, vb);
-	if (fabsf(angle_v3v3(va_vmid, vb_vmid) - (float)M_PI) > BEVEL_EPSILON_ANG) {
-		sub_v3_v3v3(vo, va, vb_vmid);
-		cross_v3_v3v3(vddir, vb_vmid, va_vmid);
-		normalize_v3(vddir);
-		add_v3_v3v3(vd, vo, vddir);
-
-		/* The cols of m are: {vmid - va, vmid - vb, vmid + vd - va -vb, va + vb - vmid;
-		 * blender transform matrices are stored such that m[i][*] is ith column;
-		 * the last elements of each col remain as they are in unity matrix */
-		sub_v3_v3v3(&r_mat[0][0], vmid, va);
-		r_mat[0][3] = 0.0f;
-		sub_v3_v3v3(&r_mat[1][0], vmid, vb);
-		r_mat[1][3] = 0.0f;
-		add_v3_v3v3(&r_mat[2][0], vmid, vd);
-		sub_v3_v3(&r_mat[2][0], va);
-		sub_v3_v3(&r_mat[2][0], vb);
-		r_mat[2][3] = 0.0f;
-		add_v3_v3v3(&r_mat[3][0], va, vb);
-		sub_v3_v3(&r_mat[3][0], vmid);
-		r_mat[3][3] = 1.0f;
 
-		return true;
+	if (is_zero_v3(va_vmid) || is_zero_v3(vb_vmid)) {
+		return false;
 	}
-	else
+
+	if (fabsf(angle_v3v3(va_vmid, vb_vmid) - (float)M_PI) <= BEVEL_EPSILON_ANG) {
 		return false;
+	}
+
+	sub_v3_v3v3(vo, va, vb_vmid);
+	cross_v3_v3v3(vddir, vb_vmid, va_vmid);
+	normalize_v3(vddir);
+	add_v3_v3v3(vd, vo, vddir);
+
+	/* The cols of m are: {vmid - va, vmid - vb, vmid + vd - va -vb, va + vb - vmid;
+		* blender transform matrices are stored such that m[i][*] is ith column;
+		* the last elements of each col remain as they are in unity matrix */
+	sub_v3_v3v3(&r_mat[0][0], vmid, va);
+	r_mat[0][3] = 0.0f;
+	sub_v3_v3v3(&r_mat[1][0], vmid, vb);
+	r_mat[1][3] = 0.0f;
+	add_v3_v3v3(&r_mat[2][0], vmid, vd);
+	sub_v3_v3(&r_mat[2][0], va);
+	sub_v3_v3(&r_mat[2][0], vb);
+	r_mat[2][3] = 0.0f;
+	add_v3_v3v3(&r_mat[3][0], va, vb);
+	sub_v3_v3(&r_mat[3][0], vmid);
+	r_mat[3][3] = 1.0f;
+
+	return true;
 }
 
 /* Like make_unit_square_map, but this one makes a matrix that transforms the