AutoVisual/IGPFamily.pde: Adding functions for to find intersections

between lines (lineIntersections()), extend lines up until a given limit
in one dimension (extendLine()) and to get the angle between two
PVectors relative to the first one (angleBetweenTwoVectors()).

1 files changed, 37 insertions, 0 deletions

diff --git a/AutoVisual/IGPFamily.pde b/AutoVisual/IGPFamily.pde
index 3108686..4d05542 100644
--- a/AutoVisual/IGPFamily.pde
+++ b/AutoVisual/IGPFamily.pde
@@ -164,6 +164,43 @@ class IGPFamily {
     translate(mid.x*(-1), mid.y*(-1));
   }
 
+	PVector lineIntersection(PVector p1, PVector p2, PVector p3, PVector p4) {
+		PVector b = PVector.sub(p2, p1);
+		PVector d = PVector.sub(p4, p3);
+
+		float b_dot_d_perp = b.x * d.y - b.y * d.x;
+		if (b_dot_d_perp == 0) {
+      return null;
+    }
+
+		PVector c = PVector.sub(p3, p1);
+		float t = (c.x * d.y - c.y * d.x) / b_dot_d_perp;
+		if (t < 0 || t > 1) { return null; }
+		float u = (c.x * b.y - c.y * b.x) / b_dot_d_perp;
+		if (u < 0 || u > 1) { return null; }
+
+		return new PVector(p1.x+t*b.x, p1.y+t*b.y);
+	}
+
+  float angleBetweenTwoVectors (PVector p1, PVector p2) {
+    float angle = atan2(p1.y-p2.y, p1.x-p2.x);
+    if (angle < 0) {
+      angle+=TWO_PI;
+    }
+    return degrees(angle);
+  }
+
+  PVector extendLine(PVector startPoint, PVector endPoint, float boundary, boolean vertical){
+    float m,n;
+    m = (endPoint.y-startPoint.y)/(endPoint.x-startPoint.x);
+    n = endPoint.y-m*endPoint.x;
+    if (vertical){
+      return new PVector((boundary-n)/m, boundary);
+    } else {
+      return new PVector(boundary, (m*boundary)+n);
+    }
+  }
+
   void display() {
     createAlphaCircle();
   }