Added Box2D

external/Box2D-2.3.1/Contributions/Enhancements/Controllers/b2TensorDampingController.cpp

@@ -0,0 +1,72 @@
+/*
+* 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 "b2TensorDampingController.h"
+
+b2TensorDampingController::b2TensorDampingController(const b2TensorDampingControllerDef* def) : b2Controller(def)
+{
+	T = def->T;
+	maxTimestep = def->maxTimestep;
+}
+
+void b2TensorDampingController::Step(const b2TimeStep& step)
+{
+	float32 timestep = step.dt;
+	if(timestep<=B2_FLT_EPSILON)
+		return;
+	if(timestep>maxTimestep && maxTimestep>0)
+		timestep = maxTimestep;
+	for(b2ControllerEdge *i=m_bodyList;i;i=i->nextBody){
+		b2Body* body = i->body;
+		if(body->IsSleeping())
+			continue;
+		b2Vec2 damping = body->GetWorldVector(
+							b2Mul(T,
+								body->GetLocalVector(
+									body->GetLinearVelocity()
+								)
+							)
+						);
+		body->SetLinearVelocity(body->GetLinearVelocity() + timestep * damping);
+	}
+}
+
+void b2TensorDampingControllerDef::SetAxisAligned(float32 xDamping, float32 yDamping)
+{
+	T.col1.x = -xDamping;
+	T.col1.y = 0;
+	T.col2.x = 0;
+	T.col2.y = -yDamping;
+	if(xDamping>0 || yDamping>0){
+		maxTimestep = 1/b2Max(xDamping,yDamping);
+	}else{
+		maxTimestep = 0;
+	}
+}
+
+void b2TensorDampingController::Destroy(b2BlockAllocator* allocator)
+{
+	allocator->Free(this, sizeof(b2TensorDampingController));
+}
+
+
+b2TensorDampingController* b2TensorDampingControllerDef::Create(b2BlockAllocator* allocator) const
+{
+	void* mem = allocator->Allocate(sizeof(b2TensorDampingController));
+	return new (mem) b2TensorDampingController(this);
+}