added suport for ballxpolygon collision ... VERY hacky

[physics.git] / src / mathw.cpp

diff --git a/src/mathw.cpp b/src/mathw.cpp
index 430a601..eda4781 100644 (file)
--- a/src/mathw.cpp
+++ b/src/mathw.cpp
@@ -1,9 +1,21 @@
-#include "mathw.h"
-
-
-/// ***** Private Varibles *****
+/*
+ *  Copyright (C) 2008 Patrik Gornicz, Gornicz_P (at) hotmail (dot) com.
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
 
-const float PI = 3.141592653;
+#include "mathw.h"
 
 
 /// ***** Public Methods *****
@@ -13,7 +25,36 @@ int mod(int x, int y)
   return x % y + (x < 0 ? y : 0);
 }
 
-/// Vector2 Math
+// Vector2 Math
+
+Vector2 vectorToLine
+(
+  const Vector2& vec,
+  float x1,
+  float y1,
+  float x2,
+  float y2
+)
+{
+    float lineSize = (float) sqrt((x1 - x2) * (x1 - x2)
+                                + (y1 - y2) * (y1 - y2));
+    if (lineSize == 0)
+        return Vector2(x1 - vec.x, y1 - vec.y);
+
+    float u = ((vec.x - x1) * (x2 - x1)
+             + (vec.y - y1) * (y2 - y1)) / (lineSize * lineSize);
+
+    if (u < 0)
+        return Vector2(x1 - vec.x, y1 - vec.y);
+    else if (u > 1)
+        return Vector2(x2 - vec.x, y2 - vec.y);
+    else
+    {
+        float ix = x1 + u * (x2 - x1);
+        float iy = y1 + u * (y2 - y1);
+        return Vector2(ix - vec.x, iy - vec.y);
+    }
+}
 
 Vector2 perp(const Vector2& vec)
 {