text: /**
   * Copyright (c) 2006-2018 LOVE Development Team
   *
   * This software is provided 'as-is', without any express or implied
   * warranty.  In no event will the authors be held liable for any damages
   * arising from the use of this software.
   *
   * Permission is granted to anyone to use this software for any purpose,
   * including commercial applications, and to alter it and redistribute it
   * freely, subject to the following restrictions:
   *
   * 1. The origin of this software must not be misrepresented; you must not
   *    claim that you wrote the original software. If you use this software
   *    in a product, an acknowledgment in the product documentation would be
   *    appreciated but is not required.
   * 2. Altered source versions must be plainly marked as such, and must not be
   *    misrepresented as being the original software.
   * 3. This notice may not be removed or altered from any source distribution.
   **/
  
  #include "Physics.h"
  
  // LOVE
  #include "common/math.h"
  #include "wrap_Body.h"
  
  namespace love
  {
  namespace physics
  {
  namespace box2d
  {
  
  float Physics::meter = Physics::DEFAULT_METER;
  
  const char *Physics::getName() const
  {
  	return "love.physics.box2d";
  }
  
  World *Physics::newWorld(float gx, float gy, bool sleep)
  {
  	return new World(b2Vec2(gx, gy), sleep);
  }
  
  Body *Physics::newBody(World *world, float x, float y, Body::Type type)
  {
  	return new Body(world, b2Vec2(x, y), type);
  }
  
  Body *Physics::newBody(World *world, Body::Type type)
  {
  	return new Body(world, b2Vec2(0, 0), type);
  }
  
  CircleShape *Physics::newCircleShape(float radius)
  {
  	return newCircleShape(0, 0, radius);
  }
  
  CircleShape *Physics::newCircleShape(float x, float y, float radius)
  {
  	b2CircleShape *s = new b2CircleShape();
  	s->m_p = Physics::scaleDown(b2Vec2(x, y));
  	s->m_radius = Physics::scaleDown(radius);
  	return new CircleShape(s);
  }
  
  PolygonShape *Physics::newRectangleShape(float w, float h)
  {
  	return newRectangleShape(0, 0, w, h, 0);
  }
  
  PolygonShape *Physics::newRectangleShape(float x, float y, float w, float h)
  {
  	return newRectangleShape(x, y, w, h, 0);
  }
  
  PolygonShape *Physics::newRectangleShape(float x, float y, float w, float h, float angle)
  {
  	b2PolygonShape *s = new b2PolygonShape();
  	s->SetAsBox(Physics::scaleDown(w/2.0f), Physics::scaleDown(h/2.0f), Physics::scaleDown(b2Vec2(x, y)), angle);
  	return new PolygonShape(s);
  }
  
  EdgeShape *Physics::newEdgeShape(float x1, float y1, float x2, float y2)
  {
  	b2EdgeShape *s = new b2EdgeShape();
  	s->Set(Physics::scaleDown(b2Vec2(x1, y1)), Physics::scaleDown(b2Vec2(x2, y2)));
  	return new EdgeShape(s);
  }
  
  int Physics::newPolygonShape(lua_State *L)
  {
  	int argc = lua_gettop(L);
  
  	bool istable = lua_istable(L, 1);
  
  	if (istable)
  		argc = (int) luax_objlen(L, 1);
  
  	if (argc % 2 != 0)
  		return luaL_error(L, "Number of vertex components must be a multiple of two.");
  
  	// 3 to 8 (b2_maxPolygonVertices) vertices
  	int vcount = argc / 2;
  	if (vcount < 3)
  		return luaL_error(L, "Expected a minimum of 3 vertices, got %d.", vcount);
  	else if (vcount > b2_maxPolygonVertices)
  		return luaL_error(L, "Expected a maximum of %d vertices, got %d.", b2_maxPolygonVertices, vcount);
  
  	b2Vec2 vecs[b2_maxPolygonVertices];
  
  	if (istable)
  	{
  		for (int i = 0; i < vcount; i++)
  		{
  			lua_rawgeti(L, 1, 1 + i * 2);
  			lua_rawgeti(L, 1, 2 + i * 2);
  			float x = (float)luaL_checknumber(L, -2);
  			float y = (float)luaL_checknumber(L, -1);
  			vecs[i] = Physics::scaleDown(b2Vec2(x, y));
  			lua_pop(L, 2);
  		}
  	}
  	else
  	{
  		for (int i = 0; i < vcount; i++)
  		{
  			float x = (float)luaL_checknumber(L, 1 + i * 2);
  			float y = (float)luaL_checknumber(L, 2 + i * 2);
  			vecs[i] = Physics::scaleDown(b2Vec2(x, y));
  		}
  	}
  
  	b2PolygonShape *s = new b2PolygonShape();
  
  	try
  	{
  		s->Set(vecs, vcount);
  	}
  	catch (love::Exception &)
  	{
  		delete s;
  		throw;
  	}
  
  	PolygonShape *p = new PolygonShape(s);
  	luax_pushtype(L, p);
  	p->release();
  	return 1;
  }
  
  int Physics::newChainShape(lua_State *L)
  {
  	int argc = lua_gettop(L)-1; // first argument is looping
  
  	bool istable = lua_istable(L, 2);
  
  	if (istable)
  		argc = (int) luax_objlen(L, 2);
  
  	if (argc % 2 != 0)
  		return luaL_error(L, "Number of vertex components must be a multiple of two.");
  
  	int vcount = argc/2;
  	bool loop = luax_checkboolean(L, 1);
  	b2Vec2 *vecs = new b2Vec2[vcount];
  
  	if (istable)
  	{
  		for (int i = 0; i < vcount; i++)
  		{
  			lua_rawgeti(L, 2, 1 + i * 2);
  			lua_rawgeti(L, 2, 2 + i * 2);
  			float x = (float)lua_tonumber(L, -2);
  			float y = (float)lua_tonumber(L, -1);
  			vecs[i] = Physics::scaleDown(b2Vec2(x, y));
  			lua_pop(L, 2);
  		}
  	}
  	else
  	{
  		for (int i = 0; i < vcount; i++)
  		{
  			float x = (float)luaL_checknumber(L, 2 + i * 2);
  			float y = (float)luaL_checknumber(L, 3 + i * 2);
  			vecs[i] = Physics::scaleDown(b2Vec2(x, y));
  		}
  	}
  
  	b2ChainShape *s = new b2ChainShape();
  
  	try
  	{
  		if (loop)
  			s->CreateLoop(vecs, vcount);
  		else
  			s->CreateChain(vecs, vcount);
  	}
  	catch (love::Exception &)
  	{
  		delete[] vecs;
  		delete s;
  		throw;
  	}
  
  	delete[] vecs;
  
  	ChainShape *c = new ChainShape(s);
  	luax_pushtype(L, c);
  	c->release();
  	return 1;
  }
  
  DistanceJoint *Physics::newDistanceJoint(Body *body1, Body *body2, float x1, float y1, float x2, float y2, bool collideConnected)
  {
  	return new DistanceJoint(body1, body2, x1, y1, x2, y2, collideConnected);
  }
  
  MouseJoint *Physics::newMouseJoint(Body *body, float x, float y)
  {
  	return new MouseJoint(body, x, y);
  }
  
  RevoluteJoint *Physics::newRevoluteJoint(Body *body1, Body *body2, float xA, float yA, float xB, float yB, bool collideConnected)
  {
  	return new RevoluteJoint(body1, body2, xA, yA, xB, yB, collideConnected);
  }
  
  RevoluteJoint *Physics::newRevoluteJoint(Body *body1, Body *body2, float xA, float yA, float xB, float yB, bool collideConnected, float referenceAngle)
  {
  	return new RevoluteJoint(body1, body2, xA, yA, xB, yB, collideConnected, referenceAngle);
  }
  
  PrismaticJoint *Physics::newPrismaticJoint(Body *body1, Body *body2, float xA, float yA, float xB, float yB, float ax, float ay, bool collideConnected)
  {
  	return new PrismaticJoint(body1, body2, xA, yA, xB, yB, ax, ay, collideConnected);
  }
  
  PrismaticJoint *Physics::newPrismaticJoint(Body *body1, Body *body2, float xA, float yA, float xB, float yB, float ax, float ay, bool collideConnected, float referenceAngle)
  {
  	return new PrismaticJoint(body1, body2, xA, yA, xB, yB, ax, ay, collideConnected, referenceAngle);
  }
  
  PulleyJoint *Physics::newPulleyJoint(Body *body1, Body *body2, b2Vec2 groundAnchor1, b2Vec2 groundAnchor2, b2Vec2 anchor1, b2Vec2 anchor2, float ratio, bool collideConnected)
  {
  	return new PulleyJoint(body1, body2, groundAnchor1, groundAnchor2, anchor1, anchor2, ratio, collideConnected);
  }
  
  GearJoint *Physics::newGearJoint(Joint *joint1, Joint *joint2, float ratio, bool collideConnected)
  {
  	return new GearJoint(joint1, joint2, ratio, collideConnected);
  }
  
  FrictionJoint *Physics::newFrictionJoint(Body *body1, Body *body2, float xA, float yA, float xB, float yB, bool collideConnected)
  {
  	return new FrictionJoint(body1, body2, xA, yA, xB, yB, collideConnected);
  }
  
  WeldJoint *Physics::newWeldJoint(Body *body1, Body *body2, float xA, float yA, float xB, float yB, bool collideConnected)
  {
  	return new WeldJoint(body1, body2, xA, yA, xB, yB, collideConnected);
  }
  
  WeldJoint *Physics::newWeldJoint(Body *body1, Body *body2, float xA, float yA, float xB, float yB, bool collideConnected, float referenceAngle)
  {
  	return new WeldJoint(body1, body2, xA, yA, xB, yB, collideConnected, referenceAngle);
  }
  
  WheelJoint *Physics::newWheelJoint(Body *body1, Body *body2, float xA, float yA, float xB, float yB, float ax, float ay, bool collideConnected)
  {
  	return new WheelJoint(body1, body2, xA, yA, xB, yB, ax, ay, collideConnected);
  }
  
  RopeJoint *Physics::newRopeJoint(Body *body1, Body *body2, float x1, float y1, float x2, float y2, float maxLength, bool collideConnected)
  {
  	return new RopeJoint(body1, body2, x1, y1, x2, y2, maxLength, collideConnected);
  }
  
  MotorJoint *Physics::newMotorJoint(Body *body1, Body *body2)
  {
  	return new MotorJoint(body1, body2);
  }
  
  MotorJoint *Physics::newMotorJoint(Body *body1, Body *body2, float correctionFactor, bool collideConnected)
  {
  	return new MotorJoint(body1, body2, correctionFactor, collideConnected);
  }
  
  
  Fixture *Physics::newFixture(Body *body, Shape *shape, float density)
  {
  	return new Fixture(body, shape, density);
  }
  
  int Physics::getDistance(lua_State *L)
  {
  	Fixture *fixtureA = luax_checktype<Fixture>(L, 1);
  	Fixture *fixtureB = luax_checktype<Fixture>(L, 2);
  	b2DistanceProxy pA, pB;
  	b2DistanceInput i;
  	b2DistanceOutput o;
  	b2SimplexCache c;
  	c.count = 0;
  
  	luax_catchexcept(L, [&]() {
  		pA.Set(fixtureA->fixture->GetShape(), 0);
  		pB.Set(fixtureB->fixture->GetShape(), 0);
  		i.proxyA = pA;
  		i.proxyB = pB;
  		i.transformA = fixtureA->fixture->GetBody()->GetTransform();
  		i.transformB = fixtureB->fixture->GetBody()->GetTransform();
  		i.useRadii = true;
  		b2Distance(&o, &c, &i);
  	});
  
  	lua_pushnumber(L, Physics::scaleUp(o.distance));
  	lua_pushnumber(L, Physics::scaleUp(o.pointA.x));
  	lua_pushnumber(L, Physics::scaleUp(o.pointA.y));
  	lua_pushnumber(L, Physics::scaleUp(o.pointB.x));
  	lua_pushnumber(L, Physics::scaleUp(o.pointB.y));
  	return 5;
  }
  
  void Physics::setMeter(float scale)
  {
  	if (scale < 1) throw love::Exception("Physics error: invalid meter");
  	Physics::meter = scale;
  }
  
  float Physics::getMeter()
  {
  	return meter;
  }
  
  void Physics::scaleDown(float &x, float &y)
  {
  	x /= meter;
  	y /= meter;
  }
  
  void Physics::scaleUp(float &x, float &y)
  {
  	x *= meter;
  	y *= meter;
  }
  
  float Physics::scaleDown(float f)
  {
  	return f/meter;
  }
  
  float Physics::scaleUp(float f)
  {
  	return f*meter;
  }
  
  b2Vec2 Physics::scaleDown(const b2Vec2 &v)
  {
  	b2Vec2 t = v;
  	scaleDown(t.x, t.y);
  	return t;
  }
  
  b2Vec2 Physics::scaleUp(const b2Vec2 &v)
  {
  	b2Vec2 t = v;
  	scaleUp(t.x, t.y);
  	return t;
  }
  
  b2AABB Physics::scaleDown(const b2AABB &aabb)
  {
  	b2AABB t;
  	t.lowerBound = scaleDown(aabb.lowerBound);
  	t.upperBound = scaleDown(aabb.upperBound);
  	return t;
  }
  
  b2AABB Physics::scaleUp(const b2AABB &aabb)
  {
  	b2AABB t;
  	t.lowerBound = scaleUp(aabb.lowerBound);
  	t.upperBound = scaleUp(aabb.upperBound);
  	return t;
  }
  
  } // box2d
  } // physics
  } // love
  