quadrilateralcowboy/idlib/geometry/Winding2D.cpp

/*
===========================================================================

Doom 3 GPL Source Code
Copyright (C) 1999-2011 id Software LLC, a ZeniMax Media company. 

This file is part of the Doom 3 GPL Source Code (?Doom 3 Source Code?).  

Doom 3 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 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 Source Code.  If not, see <http://www.gnu.org/licenses/>.

In addition, the Doom 3 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 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.

===========================================================================
*/

#include "../precompiled.h"
#pragma hdrstop

#include "Winding2D.h"


/*
============
GetAxialBevel
============
*/
bool GetAxialBevel( const idVec3 &plane1, const idVec3 &plane2, const idVec2 &point, idVec3 &bevel ) {
	if ( FLOATSIGNBITSET( plane1.x ) ^ FLOATSIGNBITSET( plane2.x ) ) {
		if ( idMath::Fabs( plane1.x ) > 0.1f && idMath::Fabs( plane2.x ) > 0.1f ) {
			bevel.x = 0.0f;
			if ( FLOATSIGNBITSET( plane1.y ) ) {
				bevel.y = -1.0f;
			}
			else {
				bevel.y = 1.0f;
			}
			bevel.z = - ( point.x * bevel.x + point.y * bevel.y );
			return true;
		}
	}
	if ( FLOATSIGNBITSET( plane1.y ) ^ FLOATSIGNBITSET( plane2.y ) ) {
		if ( idMath::Fabs( plane1.y ) > 0.1f && idMath::Fabs( plane2.y ) > 0.1f ) {
			bevel.y = 0.0f;
			if ( FLOATSIGNBITSET( plane1.x ) ) {
				bevel.x = -1.0f;
			}
			else {
				bevel.x = 1.0f;
			}
			bevel.z = - ( point.x * bevel.x + point.y * bevel.y );
			return true;
		}
	}
	return false;
}

/*
============
idWinding2D::ExpandForAxialBox
============
*/
void idWinding2D::ExpandForAxialBox( const idVec2 bounds[2] ) {
	int i, j, numPlanes;
	idVec2 v;
	idVec3 planes[MAX_POINTS_ON_WINDING_2D], plane, bevel;

	// get planes for the edges and add bevels
	for ( numPlanes = i = 0; i < numPoints; i++ ) {
		j = (i+1) % numPoints;
		if ( ( p[j] - p[i] ).LengthSqr() < 0.01f ) {
			continue;
		}
		plane = Plane2DFromPoints( p[i], p[j], true );
		if ( i ) {
			if ( GetAxialBevel( planes[numPlanes-1], plane, p[i], bevel ) ) {
				planes[numPlanes++] = bevel;
			}
		}
		assert( numPlanes < MAX_POINTS_ON_WINDING_2D );
		planes[numPlanes++] = plane;
	}
	if ( GetAxialBevel( planes[numPlanes-1], planes[0], p[0], bevel ) ) {
		planes[numPlanes++] = bevel;
	}

	// expand the planes
	for ( i = 0; i < numPlanes; i++ ) {
		v.x = bounds[ FLOATSIGNBITSET( planes[i].x ) ].x;
		v.y = bounds[ FLOATSIGNBITSET( planes[i].y ) ].y;
		planes[i].z += v.x * planes[i].x + v.y * planes[i].y;
	}

	// get intersection points of the planes
	for ( numPoints = i = 0; i < numPlanes; i++ ) {
		if ( Plane2DIntersection( planes[(i+numPlanes-1) % numPlanes], planes[i], p[numPoints] ) ) {
			numPoints++;
		}
	}
}

/*
============
idWinding2D::Expand
============
*/
void idWinding2D::Expand( const float d ) {
	int i;
	idVec2 edgeNormals[MAX_POINTS_ON_WINDING_2D];

	for ( i = 0; i < numPoints; i++ ) {
		idVec2 &start = p[i];
		idVec2 &end = p[(i+1)%numPoints];
		edgeNormals[i].x = start.y - end.y;
		edgeNormals[i].y = end.x - start.x;
		edgeNormals[i].Normalize();
		edgeNormals[i] *= d;
	}

	for ( i = 0; i < numPoints; i++ ) {
		p[i] += edgeNormals[i] + edgeNormals[(i+numPoints-1)%numPoints];
	}
}

/*
=============
idWinding2D::Split
=============
*/
int idWinding2D::Split( const idVec3 &plane, const float epsilon, idWinding2D **front, idWinding2D **back ) const {
	float			dists[MAX_POINTS_ON_WINDING_2D];
	byte			sides[MAX_POINTS_ON_WINDING_2D];
	int				counts[3];
	float			dot;
	int				i, j;
	const idVec2 *	p1, *p2;
	idVec2			mid;
	idWinding2D *	f;
	idWinding2D *	b;
	int				maxpts;

	counts[0] = counts[1] = counts[2] = 0;

	// determine sides for each point
	for ( i = 0; i < numPoints; i++ ) {
		dists[i] = dot = plane.x * p[i].x + plane.y * p[i].y + plane.z;
		if ( dot > epsilon ) {
			sides[i] = SIDE_FRONT;
		} else if ( dot < -epsilon ) {
			sides[i] = SIDE_BACK;
		} else {
			sides[i] = SIDE_ON;
		}
		counts[sides[i]]++;
	}
	sides[i] = sides[0];
	dists[i] = dists[0];
	
	*front = *back = NULL;

	// if nothing at the front of the clipping plane
	if ( !counts[SIDE_FRONT] ) {
		*back = Copy();
		return SIDE_BACK;
	}
	// if nothing at the back of the clipping plane
	if ( !counts[SIDE_BACK] ) {
		*front = Copy();
		return SIDE_FRONT;
	}

	maxpts = numPoints+4;	// cant use counts[0]+2 because of fp grouping errors

	*front = f = new idWinding2D;
	*back = b = new idWinding2D;
		
	for ( i = 0; i < numPoints; i++ ) {
		p1 = &p[i];
		
		if ( sides[i] == SIDE_ON ) {
			f->p[f->numPoints] = *p1;
			f->numPoints++;
			b->p[b->numPoints] = *p1;
			b->numPoints++;
			continue;
		}
	
		if ( sides[i] == SIDE_FRONT ) {
			f->p[f->numPoints] = *p1;
			f->numPoints++;
		}

		if ( sides[i] == SIDE_BACK ) {
			b->p[b->numPoints] = *p1;
			b->numPoints++;
		}

		if ( sides[i+1] == SIDE_ON || sides[i+1] == sides[i] ) {
			continue;
		}
			
		// generate a split point
		p2 = &p[(i+1)%numPoints];
		
		// always calculate the split going from the same side
		// or minor epsilon issues can happen
		if ( sides[i] == SIDE_FRONT ) {
			dot = dists[i] / ( dists[i] - dists[i+1] );
			for ( j = 0; j < 2; j++ ) {
				// avoid round off error when possible
				if ( plane[j] == 1.0f ) {
					mid[j] = plane.z;
				} else if ( plane[j] == -1.0f ) {
					mid[j] = -plane.z;
				} else {
					mid[j] = (*p1)[j] + dot * ((*p2)[j] - (*p1)[j]);
				}
			}
		} else {
			dot = dists[i+1] / ( dists[i+1] - dists[i] );
			for ( j = 0; j < 2; j++ ) {
				// avoid round off error when possible
				if ( plane[j] == 1.0f ) {
					mid[j] = plane.z;
				} else if ( plane[j] == -1.0f ) {
					mid[j] = -plane.z;
				} else {
					mid[j] = (*p2)[j] + dot * ( (*p1)[j] - (*p2)[j] );
				}
			}
		}

		f->p[f->numPoints] = mid;
		f->numPoints++;
		b->p[b->numPoints] = mid;
		b->numPoints++;
	}

	return SIDE_CROSS;
}

/*
============
idWinding2D::ClipInPlace
============
*/
bool idWinding2D::ClipInPlace( const idVec3 &plane, const float epsilon, const bool keepOn ) {
	int i, j, maxpts, newNumPoints;
	int sides[MAX_POINTS_ON_WINDING_2D+1], counts[3];
	float dot, dists[MAX_POINTS_ON_WINDING_2D+1];
	idVec2 *p1, *p2, mid, newPoints[MAX_POINTS_ON_WINDING_2D+4];

	counts[SIDE_FRONT] = counts[SIDE_BACK] = counts[SIDE_ON] = 0;

	for ( i = 0; i < numPoints; i++ ) {
		dists[i] = dot = plane.x * p[i].x + plane.y * p[i].y + plane.z;
		if ( dot > epsilon ) {
			sides[i] = SIDE_FRONT;
		} else if ( dot < -epsilon ) {
			sides[i] = SIDE_BACK;
		} else {
			sides[i] = SIDE_ON;
		}
		counts[sides[i]]++;
	}
	sides[i] = sides[0];
	dists[i] = dists[0];
	
	// if the winding is on the plane and we should keep it
	if ( keepOn && !counts[SIDE_FRONT] && !counts[SIDE_BACK] ) {
		return true;
	}
	if ( !counts[SIDE_FRONT] ) {
		numPoints = 0;
		return false;
	}
	if ( !counts[SIDE_BACK] ) {
		return true;
	}

	maxpts = numPoints + 4;		// cant use counts[0]+2 because of fp grouping errors
	newNumPoints = 0;

	for ( i = 0; i < numPoints; i++ ) {
		p1 = &p[i];

		if ( newNumPoints+1 > maxpts ) {
			return true;		// can't split -- fall back to original
		}
		
		if ( sides[i] == SIDE_ON ) {
			newPoints[newNumPoints] = *p1;
			newNumPoints++;
			continue;
		}
	
		if ( sides[i] == SIDE_FRONT ) {
			newPoints[newNumPoints] = *p1;
			newNumPoints++;
		}

		if ( sides[i+1] == SIDE_ON || sides[i+1] == sides[i] ) {
			continue;
		}
			
		if ( newNumPoints+1 > maxpts ) {
			return true;		// can't split -- fall back to original
		}

		// generate a split point
		p2 = &p[(i+1)%numPoints];
		
		dot = dists[i] / (dists[i] - dists[i+1]);
		for ( j = 0; j < 2; j++ ) {
			// avoid round off error when possible
			if ( plane[j] == 1.0f ) {
				mid[j] = plane.z;
			} else if ( plane[j] == -1.0f ) {
				mid[j] = -plane.z;
			} else {
				mid[j] = (*p1)[j] + dot * ((*p2)[j] - (*p1)[j]);
			}
		}

		newPoints[newNumPoints] = mid;
		newNumPoints++;
	}

	if ( newNumPoints >= MAX_POINTS_ON_WINDING_2D ) {
		return true;
	}

	numPoints = newNumPoints;
	memcpy( p, newPoints, newNumPoints * sizeof(idVec2) );

	return true;
}

/*
=============
idWinding2D::Copy
=============
*/
idWinding2D *idWinding2D::Copy( void ) const {
	idWinding2D *w;

	w = new idWinding2D;
	w->numPoints = numPoints;
	memcpy( w->p, p, numPoints * sizeof( p[0] ) );
	return w;
}

/*
=============
idWinding2D::Reverse
=============
*/
idWinding2D *idWinding2D::Reverse( void ) const {
	idWinding2D *w;
	int i;

	w = new idWinding2D;
	w->numPoints = numPoints;
	for ( i = 0; i < numPoints; i++ ) {
		w->p[ numPoints - i - 1 ] = p[i];
	}
	return w;
}

/*
============
idWinding2D::GetArea
============
*/
float idWinding2D::GetArea( void ) const {
	int i;
	idVec2 d1, d2;
	float total;

	total = 0.0f;
	for ( i = 2; i < numPoints; i++ ) {
		d1 = p[i-1] - p[0];
		d2 = p[i] - p[0];
		total += d1.x * d2.y - d1.y * d2.x;
	}
	return total * 0.5f;
}

/*
============
idWinding2D::GetCenter
============
*/
idVec2 idWinding2D::GetCenter( void ) const {
	int i;
	idVec2 center;

	center.Zero();
	for ( i = 0; i < numPoints; i++ ) {
		center += p[i];
	}
	center *= ( 1.0f / numPoints );
	return center;
}

/*
============
idWinding2D::GetRadius
============
*/
float idWinding2D::GetRadius( const idVec2 &center ) const {
	int i;
	float radius, r;
	idVec2 dir;

	radius = 0.0f;
	for ( i = 0; i < numPoints; i++ ) {
		dir = p[i] - center;
		r = dir * dir;
		if ( r > radius ) {
			radius = r;
		}
	}
	return idMath::Sqrt( radius );
}

/*
============
idWinding2D::GetBounds
============
*/
void idWinding2D::GetBounds( idVec2 bounds[2] ) const {
	int i;

	if ( !numPoints ) {
		bounds[0].x = bounds[0].y = idMath::INFINITY;
		bounds[1].x = bounds[1].y = -idMath::INFINITY;
		return;
	}
	bounds[0] = bounds[1] = p[0];
	for ( i = 1; i < numPoints; i++ ) {
		if ( p[i].x < bounds[0].x ) {
			bounds[0].x = p[i].x;
		} else if ( p[i].x > bounds[1].x ) {
			bounds[1].x = p[i].x;
		}
		if ( p[i].y < bounds[0].y ) {
			bounds[0].y = p[i].y;
		} else if ( p[i].y > bounds[1].y ) {
			bounds[1].y = p[i].y;
		}
	}
}

/*
=============
idWinding2D::IsTiny
=============
*/
#define	EDGE_LENGTH		0.2f

bool idWinding2D::IsTiny( void ) const {
	int		i;
	float	len;
	idVec2	delta;
	int		edges;

	edges = 0;
	for ( i = 0; i < numPoints; i++ ) {
		delta = p[(i+1)%numPoints] - p[i];
		len = delta.Length();
		if ( len > EDGE_LENGTH ) {
			if ( ++edges == 3 ) {
				return false;
			}
		}
	}
	return true;
}

/*
=============
idWinding2D::IsHuge
=============
*/
bool idWinding2D::IsHuge( void ) const {
	int i, j;

	for ( i = 0; i < numPoints; i++ ) {
		for ( j = 0; j < 2; j++ ) {
			if ( p[i][j] <= MIN_WORLD_COORD || p[i][j] >= MAX_WORLD_COORD ) {
				return true;
			}
		}
	}
	return false;
}

/*
=============
idWinding2D::Print
=============
*/
void idWinding2D::Print( void ) const {
	int i;

	for ( i = 0; i < numPoints; i++ ) {
		idLib::common->Printf( "(%5.1f, %5.1f)\n", p[i][0], p[i][1] );
	}
}

/*
=============
idWinding2D::PlaneDistance
=============
*/
float idWinding2D::PlaneDistance( const idVec3 &plane ) const {
	int		i;
	float	d, min, max;

	min = idMath::INFINITY;
	max = -min;
	for ( i = 0; i < numPoints; i++ ) {
		d = plane.x * p[i].x + plane.y * p[i].y + plane.z;
		if ( d < min ) {
			min = d;
			if ( FLOATSIGNBITSET( min ) & FLOATSIGNBITNOTSET( max ) ) {
				return 0.0f;
			}
		}
		if ( d > max ) {
			max = d;
			if ( FLOATSIGNBITSET( min ) & FLOATSIGNBITNOTSET( max ) ) {
				return 0.0f;
			}
		}
	}
	if ( FLOATSIGNBITNOTSET( min ) ) {
		return min;
	}
	if ( FLOATSIGNBITSET( max ) ) {
		return max;
	}
	return 0.0f;
}

/*
=============
idWinding2D::PlaneSide
=============
*/
int idWinding2D::PlaneSide( const idVec3 &plane, const float epsilon ) const {
	bool	front, back;
	int		i;
	float	d;

	front = false;
	back = false;
	for ( i = 0; i < numPoints; i++ ) {
		d = plane.x * p[i].x + plane.y * p[i].y + plane.z;
		if ( d < -epsilon ) {
			if ( front ) {
				return SIDE_CROSS;
			}
			back = true;
			continue;
		}
		else if ( d > epsilon ) {
			if ( back ) {
				return SIDE_CROSS;
			}
			front = true;
			continue;
		}
	}

	if ( back ) {
		return SIDE_BACK;
	}
	if ( front ) {
		return SIDE_FRONT;
	}
	return SIDE_ON;
}

/*
============
idWinding2D::PointInside
============
*/
bool idWinding2D::PointInside( const idVec2 &point, const float epsilon ) const {
	int i;
	float d;
	idVec3 plane;

	for ( i = 0; i < numPoints; i++ ) {
		plane = Plane2DFromPoints( p[i], p[(i+1) % numPoints] );
		d = plane.x * point.x + plane.y * point.y + plane.z;
		if ( d > epsilon ) {
			return false;
		}
	}
	return true;
}

/*
============
idWinding2D::LineIntersection
============
*/
bool idWinding2D::LineIntersection( const idVec2 &start, const idVec2 &end ) const {
	int i, numEdges;
	int sides[MAX_POINTS_ON_WINDING_2D+1], counts[3];
	float d1, d2, epsilon = 0.1f;
	idVec3 plane, edges[2];

	counts[SIDE_FRONT] = counts[SIDE_BACK] = counts[SIDE_ON] = 0;

	plane = Plane2DFromPoints( start, end );
	for ( i = 0; i < numPoints; i++ ) {
		d1 = plane.x * p[i].x + plane.y * p[i].y + plane.z;
		if ( d1 > epsilon ) {
			sides[i] = SIDE_FRONT;
		}
		else if ( d1 < -epsilon ) {
			sides[i] = SIDE_BACK;
		}
		else {
			sides[i] = SIDE_ON;
		}
		counts[sides[i]]++;
	}
	sides[i] = sides[0];

	if ( !counts[SIDE_FRONT] ) {
		return false;
	}
	if ( !counts[SIDE_BACK] ) {
		return false;
	}

	numEdges = 0;
	for ( i = 0; i < numPoints; i++ ) {
		if ( sides[i] != sides[i+1] && sides[i+1] != SIDE_ON ) {
			edges[numEdges++] = Plane2DFromPoints( p[i], p[(i+1)%numPoints] );
			if ( numEdges >= 2 ) {
				break;
			}
		}
	}
	if ( numEdges < 2 ) {
		return false;
	}

	d1 = edges[0].x * start.x + edges[0].y * start.y + edges[0].z;
	d2 = edges[0].x * end.x + edges[0].y * end.y + edges[0].z;
	if ( FLOATSIGNBITNOTSET( d1 ) & FLOATSIGNBITNOTSET( d2 ) ) {
		return false;
	}
	d1 = edges[1].x * start.x + edges[1].y * start.y + edges[1].z;
	d2 = edges[1].x * end.x + edges[1].y * end.y + edges[1].z;
	if ( FLOATSIGNBITNOTSET( d1 ) & FLOATSIGNBITNOTSET( d2 ) ) {
		return false;
	}
	return true;
}

/*
============
idWinding2D::RayIntersection
============
*/
bool idWinding2D::RayIntersection( const idVec2 &start, const idVec2 &dir, float &scale1, float &scale2, int *edgeNums ) const {
	int i, numEdges, localEdgeNums[2];
	int sides[MAX_POINTS_ON_WINDING_2D+1], counts[3];
	float d1, d2, epsilon = 0.1f;
	idVec3 plane, edges[2];

	scale1 = scale2 = 0.0f;
	counts[SIDE_FRONT] = counts[SIDE_BACK] = counts[SIDE_ON] = 0;

	plane = Plane2DFromVecs( start, dir );
	for ( i = 0; i < numPoints; i++ ) {
		d1 = plane.x * p[i].x + plane.y * p[i].y + plane.z;
		if ( d1 > epsilon ) {
			sides[i] = SIDE_FRONT;
		}
		else if ( d1 < -epsilon ) {
			sides[i] = SIDE_BACK;
		}
		else {
			sides[i] = SIDE_ON;
		}
		counts[sides[i]]++;
	}
	sides[i] = sides[0];

	if ( !counts[SIDE_FRONT] ) {
		return false;
	}
	if ( !counts[SIDE_BACK] ) {
		return false;
	}

	numEdges = 0;
	for ( i = 0; i < numPoints; i++ ) {
		if ( sides[i] != sides[i+1] && sides[i+1] != SIDE_ON ) {
			localEdgeNums[numEdges] = i;
			edges[numEdges++] = Plane2DFromPoints( p[i], p[(i+1)%numPoints] );
			if ( numEdges >= 2 ) {
				break;
			}
		}
	}
	if ( numEdges < 2 ) {
		return false;
	}

	d1 = edges[0].x * start.x + edges[0].y * start.y + edges[0].z;
	d2 = - ( edges[0].x * dir.x + edges[0].y * dir.y );
	if ( d2 == 0.0f ) {
		return false;
	}
	scale1 = d1 / d2;
	d1 = edges[1].x * start.x + edges[1].y * start.y + edges[1].z;
	d2 = - ( edges[1].x * dir.x + edges[1].y * dir.y );
	if ( d2 == 0.0f ) {
		return false;
	}
	scale2 = d1 / d2;

	if ( idMath::Fabs( scale1 ) > idMath::Fabs( scale2 ) ) {
		idSwap( scale1, scale2 );
		idSwap( localEdgeNums[0], localEdgeNums[1] );
	}

	if ( edgeNums ) {
		edgeNums[0] = localEdgeNums[0];
		edgeNums[1] = localEdgeNums[1];
	}
	return true;
}