Moving Line to Line intersection into arithb

source/blender/blenlib/BLI_arithb.h

@@ -374,6 +374,7 @@ void LocQuatSizeToMat4(float mat[][4], float loc[3], float quat[4], float size[3
 void tubemap(float x, float y, float z, float *u, float *v);
 void spheremap(float x, float y, float z, float *u, float *v);
 
+int LineIntersectLine(float v1[3], float v2[3], float v3[3], float v4[3], float i1[3], float i2[3]);
 int LineIntersectsTriangle(float p1[3], float p2[3], float v0[3], float v1[3], float v2[3], float *lambda, float *uv);
 int RayIntersectsTriangle(float p1[3], float d[3], float v0[3], float v1[3], float v2[3], float *lambda, float *uv);
 int SweepingSphereIntersectsTriangleUV(float p1[3], float p2[3], float radius, float v0[3], float v1[3], float v2[3], float *lambda, float *ipoint);

source/blender/blenlib/intern/arithb.c

@@ -4032,6 +4032,74 @@ int AxialLineIntersectsTriangle(int axis, float p1[3], float p2[3], float v0[3],
 	return 1;
 }
 
+/* Returns the number of point of interests
+ * 0 - lines are colinear
+ * 1 - lines are coplanar, i1 is set to intersection
+ * 2 - i1 and i2 are the nearest points on line 1 (v1, v2) and line 2 (v3, v4) respectively 
+ * */
+int LineIntersectLine(float v1[3], float v2[3], float v3[3], float v4[3], float i1[3], float i2[3])
+{
+	float a[3], b[3], c[3], ab[3], cb[3], dir1[3], dir2[3];
+	float d;
+	
+	VecSubf(c, v3, v1);
+	VecSubf(a, v2, v1);
+	VecSubf(b, v4, v3);
+
+	VecCopyf(dir1, a);
+	Normalize(dir1);
+	VecCopyf(dir2, b);
+	Normalize(dir2);
+	d = Inpf(dir1, dir2);
+	if (d == 1.0f || d == -1.0f) {
+		/* colinear */
+		return 0;
+	}
+
+	Crossf(ab, a, b);
+	d = Inpf(c, ab);
+
+	/* test if the two lines are coplanar */
+	if (d > -0.000001f && d < 0.000001f) {
+		Crossf(cb, c, b);
+
+		VecMulf(a, Inpf(cb, ab) / Inpf(ab, ab));
+		VecAddf(i1, v1, a);
+		VecCopyf(i2, i1);
+		
+		return 1; /* one intersection only */
+	}
+	/* if not */
+	else {
+		float n[3], t[3];
+		float v3t[3], v4t[3];
+		VecSubf(t, v1, v3);
+
+		/* offset between both plane where the lines lies */
+		Crossf(n, a, b);
+		Projf(t, t, n);
+
+		/* for the first line, offset the second line until it is coplanar */
+		VecAddf(v3t, v3, t);
+		VecAddf(v4t, v4, t);
+		
+		VecSubf(c, v3t, v1);
+		VecSubf(a, v2, v1);
+		VecSubf(b, v4t, v3);
+
+		Crossf(ab, a, b);
+		Crossf(cb, c, b);
+
+		VecMulf(a, Inpf(cb, ab) / Inpf(ab, ab));
+		VecAddf(i1, v1, a);
+
+		/* for the second line, just substract the offset from the first intersection point */
+		VecSubf(i2, i1, t);
+		
+		return 2; /* two nearest points */
+	}
+} 
+
 int AabbIntersectAabb(float min1[3], float max1[3], float min2[3], float max2[3])
 {
 	return (min1[0]<max2[0] && min1[1]<max2[1] && min1[2]<max2[2] &&

source/blender/python/api2_2x/Mathutils.c

@@ -1452,8 +1452,8 @@ PyObject *M_Mathutils_LineIntersect( PyObject * self, PyObject * args )
 						"vectors must be of the same size\n" ) );
 
 	if( vec1->size == 3 || vec1->size == 2) {
-		float a[3], b[3], c[3], ab[3], cb[3], dir1[3], dir2[3];
+		int result;
-		float d;
+		
 		if (vec1->size == 3) {
 			VECCOPY(v1, vec1->vec);
 			VECCOPY(v2, vec2->vec);
@@ -1477,63 +1477,19 @@ PyObject *M_Mathutils_LineIntersect( PyObject * self, PyObject * args )
 			v4[1] = vec4->vec[1];
 			v4[2] = 0.0f;
 		}
+		
+		result = LineIntersectLine(v1, v2, v3, v4, i1, i2);
 
-		VecSubf(c, v3, v1);
+		if (result == 0) {
-		VecSubf(a, v2, v1);
-		VecSubf(b, v4, v3);
-
-		VECCOPY(dir1, a);
-		Normalize(dir1);
-		VECCOPY(dir2, b);
-		Normalize(dir2);
-		d = Inpf(dir1, dir2);
-		if (d == 1.0f || d == -1.0f) {
 			/* colinear */
 			return EXPP_incr_ret( Py_None );
 		}
-
-		Crossf(ab, a, b);
-		d = Inpf(c, ab);
-
-		/* test if the two lines are coplanar */
-		if (d > -0.000001f && d < 0.000001f) {
-			Crossf(cb, c, b);
-
-			VecMulf(a, Inpf(cb, ab) / Inpf(ab, ab));
-			VecAddf(i1, v1, a);
-			VECCOPY(i2, i1);
-		}
-		/* if not */
 		else {
-			float n[3], t[3];
+			tuple = PyTuple_New( 2 );
-			VecSubf(t, v1, v3);
+			PyTuple_SetItem( tuple, 0, newVectorObject(i1, vec1->size, Py_NEW) );
-
+			PyTuple_SetItem( tuple, 1, newVectorObject(i2, vec1->size, Py_NEW) );
-			/* offset between both plane where the lines lies */
+			return tuple;
-			Crossf(n, a, b);
-			Projf(t, t, n);
-
-			/* for the first line, offset the second line until it is coplanar */
-			VecAddf(v3, v3, t);
-			VecAddf(v4, v4, t);
-			
-			VecSubf(c, v3, v1);
-			VecSubf(a, v2, v1);
-			VecSubf(b, v4, v3);
-
-			Crossf(ab, a, b);
-			Crossf(cb, c, b);
-
-			VecMulf(a, Inpf(cb, ab) / Inpf(ab, ab));
-			VecAddf(i1, v1, a);
-
-			/* for the second line, just substract the offset from the first intersection point */
-			VecSubf(i2, i1, t);
 		}
-
-		tuple = PyTuple_New( 2 );
-		PyTuple_SetItem( tuple, 0, newVectorObject(i1, vec1->size, Py_NEW) );
-		PyTuple_SetItem( tuple, 1, newVectorObject(i2, vec1->size, Py_NEW) );
-		return tuple;
 	}
 	else {
 		return ( EXPP_ReturnPyObjError( PyExc_TypeError,