text: /*
  ===========================================================================
  
  Doom 3 BFG Edition GPL Source Code
  Copyright (C) 1993-2012 id Software LLC, a ZeniMax Media company. 
  
  This file is part of the Doom 3 BFG Edition GPL Source Code ("Doom 3 BFG Edition Source Code").  
  
  Doom 3 BFG Edition Source Code 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 3 of the License, or
  (at your option) any later version.
  
  Doom 3 BFG Edition Source Code 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 Doom 3 BFG Edition Source Code.  If not, see <http://www.gnu.org/licenses/>.
  
  In addition, the Doom 3 BFG Edition Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU General Public License which accompanied the Doom 3 BFG Edition Source Code.  If not, please request a copy in writing from id Software at the address below.
  
  If you have questions concerning this license or the applicable additional terms, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.
  
  ===========================================================================
  */
  
  /*
  ===============================================================================
  
  	Trace model vs. polygonal model collision detection.
  
  ===============================================================================
  */
  
  #pragma hdrstop
  #include "../idlib/precompiled.h"
  
  
  #include "CollisionModel_local.h"
  
  /*
  ===============================================================================
  
  Trace through the spatial subdivision
  
  ===============================================================================
  */
  
  /*
  ================
  idCollisionModelManagerLocal::TraceTrmThroughNode
  ================
  */
  void idCollisionModelManagerLocal::TraceTrmThroughNode( cm_traceWork_t *tw, cm_node_t *node ) {
  	cm_polygonRef_t *pref;
  	cm_brushRef_t *bref;
  
  	// position test
  	if ( tw->positionTest ) {
  		// if already stuck in solid
  		if ( tw->trace.fraction == 0.0f ) {
  			return;
  		}
  		// test if any of the trm vertices is inside a brush
  		for ( bref = node->brushes; bref; bref = bref->next ) {
  			if ( idCollisionModelManagerLocal::TestTrmVertsInBrush( tw, bref->b ) ) {
  				return;
  			}
  		}
  		// if just testing a point we're done
  		if ( tw->pointTrace ) {
  			return;
  		}
  		// test if the trm is stuck in any polygons
  		for ( pref = node->polygons; pref; pref = pref->next ) {
  			if ( idCollisionModelManagerLocal::TestTrmInPolygon( tw, pref->p ) ) {
  				return;
  			}
  		}
  	}
  	else if ( tw->rotation ) {
  		// rotate through all polygons in this leaf
  		for ( pref = node->polygons; pref; pref = pref->next ) {
  			if ( idCollisionModelManagerLocal::RotateTrmThroughPolygon( tw, pref->p ) ) {
  				return;
  			}
  		}
  	}
  	else {
  		// trace through all polygons in this leaf
  		for ( pref = node->polygons; pref; pref = pref->next ) {
  			if ( idCollisionModelManagerLocal::TranslateTrmThroughPolygon( tw, pref->p ) ) {
  				return;
  			}
  		}
  	}
  }
  
  /*
  ================
  idCollisionModelManagerLocal::TraceThroughAxialBSPTree_r
  ================
  */
  //#define NO_SPATIAL_SUBDIVISION
  
  void idCollisionModelManagerLocal::TraceThroughAxialBSPTree_r( cm_traceWork_t *tw, cm_node_t *node, float p1f, float p2f, idVec3 &p1, idVec3 &p2) {
  	float		t1, t2, offset;
  	float		frac, frac2;
  	float		idist;
  	idVec3		mid;
  	int			side;
  	float		midf;
  
  	if ( !node ) {
  		return;
  	}
  
  	if ( tw->quickExit ) {
  		return;		// stop immediately
  	}
  
  	if ( tw->trace.fraction <= p1f ) {
  		return;		// already hit something nearer
  	}
  
  	// if we need to test this node for collisions
  	if ( node->polygons || (tw->positionTest && node->brushes) ) {
  		// trace through node with collision data
  		idCollisionModelManagerLocal::TraceTrmThroughNode( tw, node );
  	}
  	// if already stuck in solid
  	if ( tw->positionTest && tw->trace.fraction == 0.0f ) {
  		return;
  	}
  	// if this is a leaf node
  	if ( node->planeType == -1 ) {
  		return;
  	}
  #ifdef NO_SPATIAL_SUBDIVISION
  	idCollisionModelManagerLocal::TraceThroughAxialBSPTree_r( tw, node->children[0], p1f, p2f, p1, p2 );
  	idCollisionModelManagerLocal::TraceThroughAxialBSPTree_r( tw, node->children[1], p1f, p2f, p1, p2 );
  	return;
  #endif
  	// distance from plane for trace start and end
  	t1 = p1[node->planeType] - node->planeDist;
  	t2 = p2[node->planeType] - node->planeDist;
  	// adjust the plane distance appropriately for mins/maxs
  	offset = tw->extents[node->planeType];
  	// see which sides we need to consider
  	if ( t1 >= offset && t2 >= offset ) {
  		idCollisionModelManagerLocal::TraceThroughAxialBSPTree_r( tw, node->children[0], p1f, p2f, p1, p2 );
  		return;
  	}
  
  	if ( t1 < -offset && t2 < -offset ) {
  		idCollisionModelManagerLocal::TraceThroughAxialBSPTree_r( tw, node->children[1], p1f, p2f, p1, p2 );
  		return;
  	}
  
  	if ( t1 < t2 ) {
  		idist = 1.0f / (t1-t2);
  		side = 1;
  		frac2 = (t1 + offset) * idist;
  		frac = (t1 - offset) * idist;
  	} else if (t1 > t2) {
  		idist = 1.0f / (t1-t2);
  		side = 0;
  		frac2 = (t1 - offset) * idist;
  		frac = (t1 + offset) * idist;
  	} else {
  		side = 0;
  		frac = 1.0f;
  		frac2 = 0.0f;
  	}
  
  	// move up to the node
  	if ( frac < 0.0f ) {
  		frac = 0.0f;
  	}
  	else if ( frac > 1.0f ) {
  		frac = 1.0f;
  	}
  
  	midf = p1f + (p2f - p1f)*frac;
  
  	mid[0] = p1[0] + frac*(p2[0] - p1[0]);
  	mid[1] = p1[1] + frac*(p2[1] - p1[1]);
  	mid[2] = p1[2] + frac*(p2[2] - p1[2]);
  
  	idCollisionModelManagerLocal::TraceThroughAxialBSPTree_r( tw, node->children[side], p1f, midf, p1, mid );
  
  
  	// go past the node
  	if ( frac2 < 0.0f ) {
  		frac2 = 0.0f;
  	}
  	else if ( frac2 > 1.0f ) {
  		frac2 = 1.0f;
  	}
  		
  	midf = p1f + (p2f - p1f)*frac2;
  
  	mid[0] = p1[0] + frac2*(p2[0] - p1[0]);
  	mid[1] = p1[1] + frac2*(p2[1] - p1[1]);
  	mid[2] = p1[2] + frac2*(p2[2] - p1[2]);
  
  	idCollisionModelManagerLocal::TraceThroughAxialBSPTree_r( tw, node->children[side^1], midf, p2f, mid, p2 );
  }
  
  /*
  ================
  idCollisionModelManagerLocal::TraceThroughModel
  ================
  */
  void idCollisionModelManagerLocal::TraceThroughModel( cm_traceWork_t *tw ) {
  	float d;
  	int i, numSteps;
  	idVec3 start, end;
  	idRotation rot;
  
  	if ( !tw->rotation ) {
  		// trace through spatial subdivision and then through leafs
  		idCollisionModelManagerLocal::TraceThroughAxialBSPTree_r( tw, tw->model->node, 0, 1, tw->start, tw->end );
  	}
  	else {
  		// approximate the rotation with a series of straight line movements
  		// total length covered along circle
  		d = tw->radius * DEG2RAD( tw->angle );
  		// if more than one step
  		if ( d > CIRCLE_APPROXIMATION_LENGTH ) {
  			// number of steps for the approximation
  			numSteps = (int) (CIRCLE_APPROXIMATION_LENGTH / d);
  			// start of approximation
  			start = tw->start;
  			// trace circle approximation steps through the BSP tree
  			for ( i = 0; i < numSteps; i++ ) {
  				// calculate next point on approximated circle
  				rot.Set( tw->origin, tw->axis, tw->angle * ((float) (i+1) / numSteps) );
  				end = start * rot;
  				// trace through spatial subdivision and then through leafs
  				idCollisionModelManagerLocal::TraceThroughAxialBSPTree_r( tw, tw->model->node, 0, 1, start, end );
  				// no need to continue if something was hit already
  				if ( tw->trace.fraction < 1.0f ) {
  					return;
  				}
  				start = end;
  			}
  		}
  		else {
  			start = tw->start;
  		}
  		// last step of the approximation
  		idCollisionModelManagerLocal::TraceThroughAxialBSPTree_r( tw, tw->model->node, 0, 1, start, tw->end );
  	}
  }
  