//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//  * Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
//  * Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//  * Neither the name of NVIDIA CORPORATION nor the names of its
//    contributors may be used to endorse or promote products derived
//    from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Copyright (c) 2008-2018 NVIDIA Corporation. All rights reserved.
// Copyright (c) 2004-2008 AGEIA Technologies, Inc. All rights reserved.
// Copyright (c) 2001-2004 NovodeX AG. All rights reserved.  

#ifndef GU_INTERSECTION_CAPSULE_TRIANGLE_H
#define GU_INTERSECTION_CAPSULE_TRIANGLE_H

#include "CmPhysXCommon.h"
#include "GuCapsule.h"
#include "PsUtilities.h"

namespace physx
{
namespace Gu
{
	// PT: precomputed data for capsule-triangle test. Useful when testing the same capsule vs several triangles.
	struct CapsuleTriangleOverlapData
	{
		PxVec3		mCapsuleDir;
		float		mBDotB;
		float		mOneOverBDotB;

		void		init(const Capsule& capsule)
		{
			const PxVec3 dir = capsule.p1 - capsule.p0;
			const float BDotB = dir.dot(dir);
			mCapsuleDir		= dir;
			mBDotB			= BDotB;
			mOneOverBDotB	= BDotB!=0.0f ? 1.0f/BDotB : 0.0f;
		}
	};

	// PT: tests if projections of capsule & triangle overlap on given axis
	PX_FORCE_INLINE PxU32 testAxis(const PxVec3& p0, const PxVec3& p1, const PxVec3& p2, const Capsule& capsule, const PxVec3& axis)
	{
		// Project capsule
		float min0 = capsule.p0.dot(axis);
		float max0 = capsule.p1.dot(axis);
		if(min0>max0)
			Ps::swap(min0, max0);
		const float MR = axis.magnitude()*capsule.radius;
		min0 -= MR;
		max0 += MR;

		// Project triangle
		float min1, max1;
		{
			min1 = max1 = p0.dot(axis);
			float dp = p1.dot(axis);
			if(dp<min1)	min1 = dp;
			if(dp>max1)	max1 = dp;
			dp = p2.dot(axis);
			if(dp<min1)	min1 = dp;
			if(dp>max1)	max1 = dp;
		}

		// Test projections
		if(max0<min1 || max1<min0)
			return 0;

		return 1;
	}

	// PT: computes shortest vector going from capsule axis to triangle edge
	PX_FORCE_INLINE PxVec3 computeEdgeAxis(	const PxVec3& p, const PxVec3& a,
											const PxVec3& q, const PxVec3& b,
											float BDotB, float oneOverBDotB)	
	{
		const PxVec3 T = q - p;
		const float ADotA = a.dot(a);
		const float ADotB = a.dot(b);
		const float ADotT = a.dot(T);
		const float BDotT = b.dot(T);

		const float denom = ADotA*BDotB - ADotB*ADotB;

		float t = denom!=0.0f ? (ADotT*BDotB - BDotT*ADotB) / denom : 0.0f;
		t = PxClamp(t, 0.0f, 1.0f);

		float u = (t*ADotB - BDotT) * oneOverBDotB;

		if(u<0.0f)
		{
			u = 0.0f;
			t = ADotT / ADotA;
			t = PxClamp(t, 0.0f, 1.0f);
		}
		else if(u>1.0f)
		{
			u = 1.0f;
			t = (ADotB + ADotT) / ADotA;
			t = PxClamp(t, 0.0f, 1.0f);
		}
		return T + b*u - a*t;
	}

	/**
	*	Checks if a capsule intersects a triangle.
	*
	*	\param		normal	[in] triangle normal (orientation does not matter)
	*	\param		p0		[in] triangle's first point
	*	\param		p1		[in] triangle's second point
	*	\param		p2		[in] triangle's third point
	*	\param		capsule	[in] capsule
	*	\param		params	[in] precomputed capsule params
	*	\return		true if capsule overlaps triangle
	*/
	bool intersectCapsuleTriangle(const PxVec3& normal, const PxVec3& p0, const PxVec3& p1, const PxVec3& p2, const Gu::Capsule& capsule, const CapsuleTriangleOverlapData& params);
}
}

#endif