b2dlite/bbody.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.bbody;
  12
  13 import iv.vmath;
  14 import b2dlite.mathutils;
  15
  16
  17 // ////////////////////////////////////////////////////////////////////////// //
  18 public class Body {
  19 private:
  20   static shared uint lastidx;
  21
  22 package(b2dlite):
  23   uint midx;
  24
  25 public:
  26   Vec2 position;
  27   VFloat rotation;
  28
  29   Vec2 velocity;
  30   VFloat angularVelocity;
  31
  32   Vec2 force;
  33   VFloat torque;
  34
  35   Vec2 width;
  36
  37   VFloat friction;
  38   VFloat mass, invMass;
  39   VFloat I, invI;
  40
  41 public:
  42   this () @trusted {
  43     import core.atomic : atomicOp;
  44     midx = atomicOp!"+="(lastidx, 1);
  45     position.set(VFloatNum!(0.0), VFloatNum!(0.0));
  46     rotation = VFloatNum!(0.0);
  47     velocity.set(VFloatNum!(0.0), VFloatNum!(0.0));
  48     angularVelocity = VFloatNum!(0.0);
  49     force.set(VFloatNum!(0.0), VFloatNum!(0.0));
  50     torque = VFloatNum!(0.0);
  51     friction = VFloatNum!(0.2);
  52
  53     width.set(VFloatNum!(1.0), VFloatNum!(1.0));
  54     mass = VFloat.max;
  55     invMass = VFloatNum!(0.0);
  56     I = VFloat.max;
  57     invI = VFloatNum!(0.0);
  58   }
  59
  60   @property uint id () const pure nothrow @safe @nogc { pragma(inline, true); return midx; }
  61
  62   void set() (in auto ref Vec2 w, VFloat m) {
  63     position.set(VFloatNum!(0.0), VFloatNum!(0.0));
  64     rotation = VFloatNum!(0.0);
  65     velocity.set(VFloatNum!(0.0), VFloatNum!(0.0));
  66     angularVelocity = VFloatNum!(0.0);
  67     force.set(VFloatNum!(0.0), VFloatNum!(0.0));
  68     torque = VFloatNum!(0.0);
  69     friction = VFloatNum!(0.2);
  70     width = w;
  71     mass = m;
  72     if (mass < VFloat.max) {
  73       invMass = VFloatNum!(1.0)/mass;
  74       I = mass*(width.x*width.x+width.y*width.y)/VFloatNum!(12.0);
  75       invI = VFloatNum!(1.0)/I;
  76     } else {
  77       invMass = VFloatNum!(0.0);
  78       I = VFloat.max;
  79       invI = VFloatNum!(0.0);
  80     }
  81   }
  82
  83   void addForce() (in auto ref Vec2 f) { pragma(inline, true); force += f; }
  84
  85   int opCmp() (Body b) pure const nothrow @trusted @nogc {
  86     pragma(inline, true);
  87     return (b !is null ? b.midx == midx : 1);
  88   }
  89 }