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 public struct Mat22 {
  21 pure nothrow @safe @nogc:
  22 public:
  23   Vec2 col1, col2;
  24
  25 public:
  26   this (VFloat angle) {
  27     pragma(inline, true);
  28     import std.math : cos, sin;
  29     immutable VFloat c = cos(angle), s = sin(angle);
  30     col1.x =  c; col1.y = s;
  31     col2.x = -s; col2.y = c;
  32   }
  33
  34   this() (in auto ref Vec2 acol1, in auto ref Vec2 acol2) { pragma(inline, true); col1 = acol1; col2 = acol2; }
  35
  36   Mat22 transpose () const { pragma(inline, true); return Mat22(Vec2(col1.x, col2.x), Vec2(col1.y, col2.y)); }
  37
  38   Mat22 invert () const {
  39     pragma(inline, true);
  40     immutable VFloat a = col1.x, b = col2.x, c = col1.y, d = col2.y;
  41     Mat22 B;
  42     VFloat det = a*d-b*c;
  43     assert(det != VFloatNum!(0.0));
  44     det = VFloatNum!(1.0)/det;
  45     B.col1.x = det*d;
  46     B.col2.x = -det*b;
  47     B.col1.y = -det*c;
  48     B.col2.y = det*a;
  49     return B;
  50   }
  51
  52   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); }
  53
  54   Mat22 opBinary(string op:"+") (in auto ref Mat22 B) const { pragma(inline, true); return Mat22(col1+B.col1, col2+B.col2); }
  55   Mat22 opBinary(string op:"*") (in auto ref Mat22 B) const { pragma(inline, true); return Mat22(this*B.col1, this*B.col2); }
  56
  57   Mat22 abs() () { pragma(inline, true); return Mat22(col1.abs, col2.abs); }
  58 }
  59
  60
  61 //public VFloat cross() (in auto ref Vec2 a, in auto ref Vec2 b) { pragma(inline, true); return a.x*b.y-a.y*b.x; }
  62 public Vec2 cross() (in auto ref Vec2 a, VFloat s) { pragma(inline, true); return Vec2(s*a.y, -s*a.x); }
  63 public Vec2 cross() (VFloat s, in auto ref Vec2 a) { pragma(inline, true); return Vec2(-s*a.y, s*a.x); }
  64
  65
  66 // Random number in range [-1,1]
  67 public VFloat Random (void) {
  68   pragma(inline, true);
  69   import std.random : uniform;
  70   return cast(VFloat)uniform!"[]"(-VFloatNum!(1.0), VFloatNum!(1.0));
  71 }
  72
  73 public VFloat Random (VFloat lo, VFloat hi) {
  74   pragma(inline, true);
  75   import std.random : uniform;
  76   return cast(VFloat)uniform!"[]"(lo, hi);
  77 }