Added Box2D

external/Box2D-2.3.1/Contributions/Enhancements/Controllers/b2GravityController.cpp

@@ -0,0 +1,70 @@
+/*
+* Copyright (c) 2006-2007 Erin Catto http://www.gphysics.com
+*
+* 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 "b2GravityController.h"
+
+b2GravityController::b2GravityController(const b2GravityControllerDef* def) : b2Controller(def)
+{
+	G = def->G;
+	invSqr = def->invSqr;
+}
+
+void b2GravityController::Step(const b2TimeStep& step)
+{
+	B2_NOT_USED(step);
+	if(invSqr){
+		for(b2ControllerEdge *i=m_bodyList;i;i=i->nextBody){
+			b2Body* body1 = i->body;
+			for(b2ControllerEdge *j=m_bodyList;j!=i;j=j->nextBody){
+				b2Body* body2 = j->body;
+				b2Vec2 d = body2->GetWorldCenter() - body1->GetWorldCenter();
+				float32 r2 = d.LengthSquared();
+				if(r2 < B2_FLT_EPSILON)
+					continue;
+				b2Vec2 f = G / r2 / sqrt(r2) * body1->GetMass() * body2->GetMass() * d;
+				body1->ApplyForce(f      , body1->GetWorldCenter());
+				body2->ApplyForce(-1.0f*f, body2->GetWorldCenter());
+			}
+		}
+	}else{
+		for(b2ControllerEdge *i=m_bodyList;i;i=i->nextBody){
+			b2Body* body1 = i->body;
+			for(b2ControllerEdge *j=m_bodyList;j!=i;j=j->nextBody){
+				b2Body* body2 = j->body;
+				b2Vec2 d = body2->GetWorldCenter() - body1->GetWorldCenter();
+				float32 r2 = d.LengthSquared();
+				if(r2 < B2_FLT_EPSILON)
+					continue;
+				b2Vec2 f = G / r2 * body1->GetMass() * body2->GetMass() * d;
+				body1->ApplyForce(f      , body1->GetWorldCenter());
+				body2->ApplyForce(-1.0f*f, body2->GetWorldCenter());
+			}
+		}
+	}
+}
+
+void b2GravityController::Destroy(b2BlockAllocator* allocator)
+{
+	allocator->Free(this, sizeof(b2GravityController));
+}
+
+b2GravityController* b2GravityControllerDef::Create(b2BlockAllocator* allocator) const
+{
+	void* mem = allocator->Allocate(sizeof(b2GravityController));
+	return new (mem) b2GravityController(this);
+}