/**
 * $Id: KX_RayCast.cpp 28415 2010-04-25 15:24:18Z campbellbarton $
 *
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): none yet.
 *
 * ***** END GPL LICENSE BLOCK *****
 * KX_MouseFocusSensor determines mouse in/out/over events.
 */

#include <stdlib.h>
#include <stdio.h>

#include "KX_RayCast.h"

#include "MT_Point3.h"
#include "MT_Vector3.h"

#include "KX_IPhysicsController.h"
#include "PHY_IPhysicsEnvironment.h"
#include "PHY_IPhysicsController.h"

KX_RayCast::KX_RayCast(KX_IPhysicsController* ignoreController, bool faceNormal, bool faceUV)
	:PHY_IRayCastFilterCallback(dynamic_cast<PHY_IPhysicsController*>(ignoreController), faceNormal, faceUV) 
{
}

void KX_RayCast::reportHit(PHY_RayCastResult* result)
{
	m_hitFound = true;
	m_hitPoint.setValue((const float*)result->m_hitPoint);
	m_hitNormal.setValue((const float*)result->m_hitNormal);
	m_hitUVOK = result->m_hitUVOK;
	m_hitUV.setValue((const float*)result->m_hitUV);
	m_hitMesh = result->m_meshObject;
	m_hitPolygon = result->m_polygon;
}

bool KX_RayCast::RayTest(PHY_IPhysicsEnvironment* physics_environment, const MT_Point3& _frompoint, const MT_Point3& topoint, KX_RayCast& callback)
{
	if(physics_environment==NULL) return false; /* prevents crashing in some cases */
	
	// Loops over all physics objects between frompoint and topoint,
	// calling callback.RayHit for each one.
	//
	// callback.RayHit should return true to stop looking, or false to continue.
	//
	// returns true if an object was found, false if not.
	
	MT_Point3 frompoint(_frompoint);
	const MT_Vector3 todir( (topoint - frompoint).safe_normalized() );
	MT_Point3 prevpoint(_frompoint+todir*(-1.f));
	
	PHY_IPhysicsController* hit_controller;

	while((hit_controller = physics_environment->rayTest(callback,
			frompoint.x(),frompoint.y(),frompoint.z(),
			topoint.x(),topoint.y(),topoint.z())) != NULL) 
	{
		KX_ClientObjectInfo* info = static_cast<KX_ClientObjectInfo*>(hit_controller->getNewClientInfo());
		
		if (!info)
		{
			printf("no info!\n");
			MT_assert(info && "Physics controller with no client object info");
			break;
		}
		
		// The biggest danger to endless loop, prevent this by checking that the
		// hit point always progresses along the ray direction..
		prevpoint -= callback.m_hitPoint;
		if (prevpoint.length2() < MT_EPSILON)
			break;

		if (callback.RayHit(info))
			// caller may decide to stop the loop and still cancel the hit
			return callback.m_hitFound;

		// Skip past the object and keep tracing.
		// Note that retrieving in a single shot multiple hit points would be possible 
		// but it would require some change in Bullet.
		prevpoint = callback.m_hitPoint;
		/* We add 0.001 of fudge, so that if the margin && radius == 0., we don't endless loop. */
		MT_Scalar marg = 0.001 + hit_controller->GetMargin();
		marg *= 2.f;
		/* Calculate the other side of this object */
		MT_Scalar h = MT_abs(todir.dot(callback.m_hitNormal));
		if (h <= 0.01)
			// the normal is almost orthogonal to the ray direction, cannot compute the other side
			break;
		marg /= h; 
		frompoint = callback.m_hitPoint + marg * todir;
		// verify that we are not passed the to point
		if ((topoint - frompoint).dot(todir) < 0.f)
			break;
	}
	return false;
}