/*************************************************************************
*                                                                       *
* Open Dynamics Engine, Copyright (C) 2001-2003 Russell L. Smith.       *
* All rights reserved.  Email: russ@q12.org   Web: www.q12.org          *
*                                                                       *
* This library is free software; you can redistribute it and/or         *
* modify it under the terms of EITHER:                                  *
*   (1) The GNU Lesser General Public License as published by the Free  *
*       Software Foundation; either version 2.1 of the License, or (at  *
*       your option) any later version. The text of the GNU Lesser      *
*       General Public License is included with this library in the     *
*       file LICENSE.TXT.                                               *
*   (2) The BSD-style license that is included with this library in     *
*       the file LICENSE-BSD.TXT.                                       *
*                                                                       *
* This library is distributed in the hope that it will be useful,       *
* but WITHOUT ANY WARRANTY; without even the implied warranty of        *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the files    *
* LICENSE.TXT and LICENSE-BSD.TXT for more details.                     *
*                                                                       *
*************************************************************************/


/*
 * Cylinder-Plane collider by Christoph Beyer ( boernerb@web.de )
 *
 * This testing basically comes down to testing the intersection
 * of the cylinder caps (discs) with the plane.
 * 
 */

#include <ode/collision.h>
#include <ode/matrix.h>
#include <ode/rotation.h>
#include <ode/odemath.h>
#include <ode/objects.h>

#include "collision_kernel.h"	// for dxGeom

int dCollideCylinderPlane(dxGeom *Cylinder, dxGeom *Plane, int flags, dContactGeom *contact, int skip)
{

	unsigned char* pContactData = (unsigned char*)contact;
	int GeomCount = 0; // count of used contactgeoms

	const dReal toleranz = REAL(0.0001f);


	// Get the properties of the cylinder (length+radius)
	dReal radius, length;
	dGeomCylinderGetParams(Cylinder, &radius, &length);
	dVector3 &cylpos = Cylinder->final_posr->pos;
	// and the plane
	dVector4 planevec;
	dGeomPlaneGetParams(Plane, planevec);
	dVector3 PlaneNormal = {planevec[0],planevec[1],planevec[2]};

	dVector3 G1Pos1, G1Pos2, vDir1;
	vDir1[0] = Cylinder->final_posr->R[2];
	vDir1[1] = Cylinder->final_posr->R[6];
	vDir1[2] = Cylinder->final_posr->R[10];

	dReal s;
	s = dMUL(length,REAL(0.5));
	G1Pos2[0] = dMUL(vDir1[0],s) + cylpos[0];
	G1Pos2[1] = dMUL(vDir1[1],s) + cylpos[1];
	G1Pos2[2] = dMUL(vDir1[2],s) + cylpos[2];

	G1Pos1[0] = dMUL(vDir1[0],-s) + cylpos[0];
	G1Pos1[1] = dMUL(vDir1[1],-s) + cylpos[1];
	G1Pos1[2] = dMUL(vDir1[2],-s) + cylpos[2];

	dVector3 C;

	// parallel-check
	s = dMUL(vDir1[0],PlaneNormal[0]) + dMUL(vDir1[1],PlaneNormal[1]) + dMUL(vDir1[2],PlaneNormal[2]);
	if(s < 0)
		s += REAL(1.0); // is ca. 0, if vDir1 and PlaneNormal are parallel
	else
		s -= REAL(1.0); // is ca. 0, if vDir1 and PlaneNormal are parallel
	if(s < toleranz && s > (-toleranz))
	{
		// discs are parallel to the plane

		// 1.compute if, and where contacts are
		dVector3 P;
		s = planevec[3] - dMUL(planevec[0],G1Pos1[0]) - dMUL(planevec[1],G1Pos1[1]) - dMUL(planevec[2],G1Pos1[2]);
		dReal t;
		t = planevec[3] - dMUL(planevec[0],G1Pos2[0]) - dMUL(planevec[1],G1Pos2[1]) - dMUL(planevec[2],G1Pos2[2]);
		if(s >= t) // s == t does never happen, 
		{
			if(s >= 0)
			{
				// 1. Disc
				P[0] = G1Pos1[0];
				P[1] = G1Pos1[1];
				P[2] = G1Pos1[2];
			}
			else
				return GeomCount; // no contacts
		}
		else
		{
			if(t >= 0)
			{
				// 2. Disc
				P[0] = G1Pos2[0];
				P[1] = G1Pos2[1];
				P[2] = G1Pos2[2];
			}
			else
				return GeomCount; // no contacts
		}

		// 2. generate a coordinate-system on the disc
		dVector3 V1, V2;
		if(vDir1[0] < toleranz && vDir1[0] > (-toleranz))
		{
			// not x-axis
			V1[0] = vDir1[0] + REAL(1.0); // random value
			V1[1] = vDir1[1];
			V1[2] = vDir1[2];
		}
		else
		{
			// maybe x-axis
			V1[0] = vDir1[0];
			V1[1] = vDir1[1] + REAL(1.0); // random value
			V1[2] = vDir1[2];
		}
		// V1 is now another direction than vDir1
		// Cross-product
	    V2[0] = dMUL(V1[1],vDir1[2]) - dMUL(V1[2],vDir1[1]);
		V2[1] = dMUL(V1[2],vDir1[0]) - dMUL(V1[0],vDir1[2]);
		V2[2] = dMUL(V1[0],vDir1[1]) - dMUL(V1[1],vDir1[0]);
		// make unit V2
		t = dSqrt(dMUL(V2[0],V2[0]) + dMUL(V2[1],V2[1]) + dMUL(V2[2],V2[2]));
		t = dDIV(radius,t);
		V2[0] = dMUL(V2[0],t);
		V2[1] = dMUL(V2[1],t);
		V2[2] = dMUL(V2[2],t);
		// cross again
	    V1[0] = dMUL(V2[1],vDir1[2]) - dMUL(V2[2],vDir1[1]);
		V1[1] = dMUL(V2[2],vDir1[0]) - dMUL(V2[0],vDir1[2]);
		V1[2] = dMUL(V2[0],vDir1[1]) - dMUL(V2[1],vDir1[0]);
		// |V2| is 'radius' and vDir1 unit, so |V1| is 'radius'
		// V1 = first axis
		// V2 = second axis

		// 3. generate contactpoints

		// Potential contact 1
		contact->pos[0] = P[0] + V1[0];
		contact->pos[1] = P[1] + V1[1];
		contact->pos[2] = P[2] + V1[2];
		contact->depth = planevec[3] - dMUL(planevec[0],contact->pos[0]) - dMUL(planevec[1],contact->pos[1]) - dMUL(planevec[2],contact->pos[2]);
		if(contact->depth > 0)
		{
			contact->normal[0] = PlaneNormal[0];
			contact->normal[1] = PlaneNormal[1];
			contact->normal[2] = PlaneNormal[2];
			contact->g1 = Cylinder;
			contact->g2 = Plane;
			GeomCount++;
			if( GeomCount >= (flags & 0x0ffff))
				return GeomCount; // enough contactgeoms
			pContactData += skip;
			contact = (dContactGeom*)pContactData;
		}

		// Potential contact 2
		contact->pos[0] = P[0] - V1[0];
		contact->pos[1] = P[1] - V1[1];
		contact->pos[2] = P[2] - V1[2];
		contact->depth = planevec[3] - dMUL(planevec[0],contact->pos[0]) - dMUL(planevec[1],contact->pos[1]) - dMUL(planevec[2],contact->pos[2]);
		if(contact->depth > 0)
		{
			contact->normal[0] = PlaneNormal[0];
			contact->normal[1] = PlaneNormal[1];
			contact->normal[2] = PlaneNormal[2];
			contact->g1 = Cylinder;
			contact->g2 = Plane;
			GeomCount++;
			if( GeomCount >= (flags & 0x0ffff))
				return GeomCount; // enough contactgeoms
			pContactData += skip;
			contact = (dContactGeom*)pContactData;
		}

		// Potential contact 3
		contact->pos[0] = P[0] + V2[0];
		contact->pos[1] = P[1] + V2[1];
		contact->pos[2] = P[2] + V2[2];
		contact->depth = planevec[3] - dMUL(planevec[0],contact->pos[0]) - dMUL(planevec[1],contact->pos[1]) - dMUL(planevec[2],contact->pos[2]);
		if(contact->depth > 0)
		{
			contact->normal[0] = PlaneNormal[0];
			contact->normal[1] = PlaneNormal[1];
			contact->normal[2] = PlaneNormal[2];
			contact->g1 = Cylinder;
			contact->g2 = Plane;
			GeomCount++;
			if( GeomCount >= (flags & 0x0ffff))
				return GeomCount; // enough contactgeoms
			pContactData += skip;
			contact = (dContactGeom*)pContactData;
		}

		// Potential contact 4
		contact->pos[0] = P[0] - V2[0];
		contact->pos[1] = P[1] - V2[1];
		contact->pos[2] = P[2] - V2[2];
		contact->depth = planevec[3] - dMUL(planevec[0],contact->pos[0]) - dMUL(planevec[1],contact->pos[1]) - dMUL(planevec[2],contact->pos[2]);
		if(contact->depth > 0)
		{
			contact->normal[0] = PlaneNormal[0];
			contact->normal[1] = PlaneNormal[1];
			contact->normal[2] = PlaneNormal[2];
			contact->g1 = Cylinder;
			contact->g2 = Plane;
			GeomCount++;
			if( GeomCount >= (flags & 0x0ffff))
				return GeomCount; // enough contactgeoms
			pContactData += skip;
			contact = (dContactGeom*)pContactData;
		}
	}
	else
	{
		dReal t = -(dMUL((-PlaneNormal[0]),vDir1[0]) + dMUL((-PlaneNormal[1]),vDir1[1]) + dMUL((-PlaneNormal[2]),vDir1[2]));
		C[0] = dMUL(vDir1[0],t) - PlaneNormal[0];
		C[1] = dMUL(vDir1[1],t) - PlaneNormal[1];
		C[2] = dMUL(vDir1[2],t) - PlaneNormal[2];
		s = dSqrt(dMUL(C[0],C[0]) + dMUL(C[1],C[1]) + dMUL(C[2],C[2]));
		// move C onto the circle
		s = dDIV(radius,s);
		C[0] = dMUL(C[0],s);
		C[1] = dMUL(C[1],s);
		C[2] = dMUL(C[2],s);

		// deepest point of disc 1
		contact->pos[0] = C[0] + G1Pos1[0];
		contact->pos[1] = C[1] + G1Pos1[1];
		contact->pos[2] = C[2] + G1Pos1[2];

		// depth of the deepest point
		contact->depth = planevec[3] - dMUL(planevec[0],contact->pos[0]) - dMUL(planevec[1],contact->pos[1]) - dMUL(planevec[2],contact->pos[2]);
		if(contact->depth >= 0)
		{
			contact->normal[0] = PlaneNormal[0];
			contact->normal[1] = PlaneNormal[1];
			contact->normal[2] = PlaneNormal[2];
			contact->g1 = Cylinder;
			contact->g2 = Plane;
			GeomCount++;
			if( GeomCount >= (flags & 0x0ffff))
				return GeomCount; // enough contactgeoms
			pContactData += skip;
			contact = (dContactGeom*)pContactData;
		}

		// C is still computed

		// deepest point of disc 2
		contact->pos[0] = C[0] + G1Pos2[0];
		contact->pos[1] = C[1] + G1Pos2[1];
		contact->pos[2] = C[2] + G1Pos2[2];

		// depth of the deepest point
		contact->depth = planevec[3] - dMUL(planevec[0],contact->pos[0]) - dMUL(planevec[1],contact->pos[1]) - dMUL(planevec[2],contact->pos[2]);
		if(contact->depth >= 0)
		{
			contact->normal[0] = PlaneNormal[0];
			contact->normal[1] = PlaneNormal[1];
			contact->normal[2] = PlaneNormal[2];
			contact->g1 = Cylinder;
			contact->g2 = Plane;
			GeomCount++;
			if( GeomCount >= (flags & 0x0ffff))
				return GeomCount; // enough contactgeoms
			pContactData += skip;
			contact = (dContactGeom*)pContactData;
		}
	}
	return GeomCount;
}