intersect line

pgfw/Delegate.py

@@ -62,7 +62,7 @@ class Delegate(GameChild):
         self.subscribers[kind].remove(callback)
 
     def compare(self, evt, commands=None, cancel=False, **attributes):
-        if evt.type == self.command_event_id:
+        if self.is_command(evt):
             self.add_cancel_flag_to_attributes(attributes, cancel)
         if commands is not None and not isinstance(commands, list):
             commands = [commands]

pgfw/extension.py

@@ -58,3 +58,43 @@ def place_in_rect(rect, incoming, contain=True, *args):
                     break
             if not collides:
                 break
+
+def get_intersection(p0, p1, p2, p3):
+    x0, y0 = p0
+    x1, y1 = p1
+    x2, y2 = p2
+    x3, y3 = p3
+    a0 = y1 - y0
+    b0 = x0 - x1
+    c0 = x1 * y0 - x0 * y1
+    r2 = a0 * x2 + b0 * y2 + c0
+    r3 = a0 * x3 + b0 * y3 + c0
+    if r2 != 0 and r3 != 0 and r2 * r3 > 0:
+        return None
+    a1 = y3 - y2
+    b1 = x2 - x3
+    c1 = x3 * y2 - x2 * y3
+    r0 = a1 * x0 + b1 * y0 + c1
+    r1 = a1 * x1 + b1 * y1 + c1
+    if r0 != 0 and r1 != 0 and r0 * r1 > 0:
+        return None
+    denominator = a0 * b1 - a1 * b0
+    if denominator == 0:
+        return (x0 + x1 + x2 + x3) / 4, (y0 + y1 + y2 + y3) / 4
+    if denominator < 0:
+        offset = -denominator / 2
+    else:
+        offset = denominator / 2
+    numerator = b0 * c1 - b1 * c0
+    x = ((-1, 1)[numerator < 0] * offset + numerator) / denominator
+    numerator = a1 * c0 - a0 * c1
+    y = ((-1, 1)[numerator < 0] * offset + numerator) / denominator
+    return x, y
+
+def collide_line_with_rect(rect, p0, p1):
+    for line in ((rect.topleft, rect.topright),
+                 (rect.topright, rect.bottomright),
+                 (rect.bottomright, rect.bottomleft),
+                 (rect.bottomleft, rect.topleft)):
+        if get_intersection(p0, p1, *line):
+            return True