b2dlite/mathutils.d

   1 /*
   2  * Copyright (c) 2006-2007 Erin Catto http://www.gphysics.com
   3  *
   4  * Permission to use, copy, modify, distribute and sell this software
   5  * and its documentation for any purpose is hereby granted without fee,
   6  * provided that the above copyright notice appear in all copies.
   7  * Erin Catto makes no representations about the suitability
   8  * of this software for any purpose.
   9  * It is provided "as is" without express or implied warranty.
  10  */
  11 module b2dlite.mathutils;
  12
  13 import iv.vmath;
  14
  15 public alias Vec2 = VecN!(2, float);
  16 public alias VFloat = Vec2.VFloat;
  17 public alias VFloatNum = Vec2.VFloatNum;
  18
  19
  20 // ////////////////////////////////////////////////////////////////////////// //
  21 public struct Mat22 {
  22 nothrow @safe @nogc:
  23 public:
  24   Vec2 col1, col2;
  25
  26 public:
  27   this (VFloat angle) {
  28     pragma(inline, true);
  29     import core.stdc.math : cosf, sinf;
  30     immutable VFloat c = cosf(angle), s = sinf(angle);
  31     col1.x =  c; col1.y = s;
  32     col2.x = -s; col2.y = c;
  33   }
  34
  35 pure:
  36   this() (in auto ref Vec2 acol1, in auto ref Vec2 acol2) { pragma(inline, true); col1 = acol1; col2 = acol2; }
  37
  38   Mat22 transpose () const { pragma(inline, true); return Mat22(Vec2(col1.x, col2.x), Vec2(col1.y, col2.y)); }
  39
  40   Mat22 invert () const {
  41     pragma(inline, true);
  42     immutable VFloat a = col1.x, b = col2.x, c = col1.y, d = col2.y;
  43     Mat22 B;
  44     VFloat det = a*d-b*c;
  45     assert(det != VFloatNum!(0.0));
  46     det = VFloatNum!(1.0)/det;
  47     B.col1.x = det*d;
  48     B.col2.x = -det*b;
  49     B.col1.y = -det*c;
  50     B.col2.y = det*a;
  51     return B;
  52   }
  53
  54   Vec2 opBinary(string op:"*") (in auto ref Vec2 v) const { pragma(inline, true); return Vec2(col1.x*v.x+col2.x*v.y, col1.y*v.x+col2.y*v.y); }
  55
  56   Mat22 opBinary(string op:"+") (in auto ref Mat22 B) const { pragma(inline, true); return Mat22(col1+B.col1, col2+B.col2); }
  57   Mat22 opBinary(string op:"*") (in auto ref Mat22 B) const { pragma(inline, true); return Mat22(this*B.col1, this*B.col2); }
  58
  59   Mat22 abs() () { pragma(inline, true); return Mat22(col1.abs, col2.abs); }
  60 }
  61
  62
  63 // ////////////////////////////////////////////////////////////////////////// //
  64 package(b2dlite) Vec2 fcross() (VFloat s, in auto ref Vec2 a) { pragma(inline, true); return Vec2(-s*a.y, s*a.x); }