Delphi/CppBuilder

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Delphi

UPulleys.pas：源码内容

							unit UPulleys;
interface
{$I ......SourcePhysics2D.inc}
uses
   UMain, UPhysics2DTypes, UPhysics2D, SysUtils;
type
   TPulleys = class(TTester)
   public
      m_joint1: Tb2PulleyJoint;
      constructor Create; override;
      procedure Step(var settings: TSettings; timeStep: Float); override;
   end;
implementation
{ TPulleys }
constructor TPulleys.Create;
var
   ground: Tb2Body;
   bd: Tb2BodyDef;
   sd: Tb2PolygonDef;
   body1, body2: Tb2Body;
   pulleyDef: Tb2PulleyJointDef;
   b, y, L: Float;
begin
   inherited;
   begin
      sd := Tb2PolygonDef.Create;
      sd.SetAsBox(50.0, 10.0);
      bd := Tb2BodyDef.Create;
      {$IFDEF OP_OVERLOAD}
      bd.position.SetValue(0.0, -10.0);
      {$ELSE}
      SetValue(bd.position, 0.0, -10.0);
      {$ENDIF}
      ground := m_world.CreateBody(bd);
      ground.CreateShape(sd);
   end;
   begin
      b := 4.0;
      y := 16.0;
      L := 12.0;
      sd := Tb2PolygonDef.Create;
      sd.SetAsBox(2, b);
      sd.density := 5.0;
      bd := Tb2BodyDef.Create;
      {$IFDEF OP_OVERLOAD}
      bd.position.SetValue(-10.0, y);
      {$ELSE}
      SetValue(bd.position, -10.0, y);
      {$ENDIF}
      body1 := m_world.CreateBody(bd, False);
      body1.CreateShape(sd, False);
      body1.SetMassFromShapes;
      {$IFDEF OP_OVERLOAD}
      bd.position.SetValue(10.0, y);
      {$ELSE}
      SetValue(bd.position, 10.0, y);
      {$ENDIF}
      body2 := m_world.CreateBody(bd);
      body2.CreateShape(sd);
      body2.SetMassFromShapes;
      pulleyDef := Tb2PulleyJointDef.Create;
      pulleyDef.Initialize(body1, body2, MakeVector(-10.0, y + b + L),
         MakeVector(10.0, y + b + L), MakeVector(-10.0, y + b), MakeVector(10.0, y + b), 2.0);
      m_joint1 := Tb2PulleyJoint(m_world.CreateJoint(pulleyDef));
   end;
end;
procedure TPulleys.Step(var settings: TSettings; timeStep: Float);
var
   L: Float;
begin
   inherited;
   L := m_joint1.GetLength1 + m_joint1.GetRatio * m_joint1.GetLength2;
   DrawText(Format('L1 + %4.2f * L2 = %4.2f', [m_joint1.GetRatio, L]));
end;
initialization
   RegisterTestEntry('Pulleys', TPulleys);
end.

						