netradiant-custom/radiant/winding.cpp

/*
   Copyright (C) 1999-2006 Id Software, Inc. and contributors.
   For a list of contributors, see the accompanying CONTRIBUTORS file.

   This file is part of GtkRadiant.

   GtkRadiant 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.

   GtkRadiant 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 GtkRadiant; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include "winding.h"

#include <algorithm>

#include "math/line.h"


inline double plane3_distance_to_point( const Plane3& plane, const DoubleVector3& point ){
	return vector3_dot( point, plane.normal() ) - plane.dist();
}

inline double plane3_distance_to_point( const Plane3& plane, const Vector3& point ){
	return vector3_dot( point, plane.normal() ) - plane.dist();
}

/// \brief Returns the point at which \p line intersects \p plane, or an undefined value if there is no intersection.
inline DoubleVector3 line_intersect_plane( const DoubleLine& line, const Plane3& plane ){
	return line.origin + vector3_scaled(
			   line.direction,
			   -plane3_distance_to_point( plane, line.origin )
			   / vector3_dot( line.direction, plane.normal() )
			   );
}

inline bool float_is_largest_absolute( double axis, double other ){
	return fabs( axis ) > fabs( other );
}

/// \brief Returns the index of the component of \p v that has the largest absolute value.
inline int vector3_largest_absolute_component_index( const DoubleVector3& v ){
	return ( float_is_largest_absolute( v[1], v[0] ) )
		   ? ( float_is_largest_absolute( v[1], v[2] ) )
		   ? 1
		   : 2
		   : ( float_is_largest_absolute( v[0], v[2] ) )
		   ? 0
		   : 2;
}

/// \brief Returns the infinite line that is the intersection of \p plane and \p other.
DoubleLine plane3_intersect_plane3( const Plane3& plane, const Plane3& other ){
	DoubleLine line;
	line.direction = vector3_cross( plane.normal(), other.normal() );
	switch ( vector3_largest_absolute_component_index( line.direction ) )
	{
	case 0:
		line.origin.x() = 0;
		line.origin.y() = ( -other.dist() * plane.normal().z() - -plane.dist() * other.normal().z() ) / line.direction.x();
		line.origin.z() = ( -plane.dist() * other.normal().y() - -other.dist() * plane.normal().y() ) / line.direction.x();
		break;
	case 1:
		line.origin.x() = ( -plane.dist() * other.normal().z() - -other.dist() * plane.normal().z() ) / line.direction.y();
		line.origin.y() = 0;
		line.origin.z() = ( -other.dist() * plane.normal().x() - -plane.dist() * other.normal().x() ) / line.direction.y();
		break;
	case 2:
		line.origin.x() = ( -other.dist() * plane.normal().y() - -plane.dist() * other.normal().y() ) / line.direction.z();
		line.origin.y() = ( -plane.dist() * other.normal().x() - -other.dist() * plane.normal().x() ) / line.direction.z();
		line.origin.z() = 0;
		break;
	default:
		break;
	}

	return line;
}


/// \brief Keep the value of \p infinity as small as possible to improve precision in Winding_Clip.
void Winding_createInfinite( FixedWinding& winding, const Plane3& plane, double infinity ){
	double max = -infinity;
	int x = -1;
	for ( int i = 0 ; i < 3; i++ )
	{
		double d = fabs( plane.normal()[i] );
		if ( d > max ) {
			x = i;
			max = d;
		}
	}
	if ( x == -1 ) {
		globalErrorStream() << "invalid plane\n";
		return;
	}

	DoubleVector3 vup = g_vector3_identity;
	switch ( x )
	{
	case 0:
	case 1:
		vup[2] = 1;
		break;
	case 2:
		vup[0] = 1;
		break;
	}


	vector3_add( vup, vector3_scaled( plane.normal(), -vector3_dot( vup, plane.normal() ) ) );
	vector3_normalise( vup );

	DoubleVector3 org = vector3_scaled( plane.normal(), plane.dist() );

	DoubleVector3 vright = vector3_cross( vup, plane.normal() );

	vector3_scale( vup, infinity );
	vector3_scale( vright, infinity );

	// project a really big  axis aligned box onto the plane

	DoubleLine r1, r2, r3, r4;
	r1.origin = vector3_added( vector3_subtracted( org, vright ), vup );
	r1.direction = vector3_normalised( vright );
	winding.push_back( FixedWindingVertex( r1.origin, r1, c_brush_maxFaces ) );
	r2.origin = vector3_added( vector3_added( org, vright ), vup );
	r2.direction = vector3_normalised( vector3_negated( vup ) );
	winding.push_back( FixedWindingVertex( r2.origin, r2, c_brush_maxFaces ) );
	r3.origin = vector3_subtracted( vector3_added( org, vright ), vup );
	r3.direction = vector3_normalised( vector3_negated( vright ) );
	winding.push_back( FixedWindingVertex( r3.origin, r3, c_brush_maxFaces ) );
	r4.origin = vector3_subtracted( vector3_subtracted( org, vright ), vup );
	r4.direction = vector3_normalised( vup );
	winding.push_back( FixedWindingVertex( r4.origin, r4, c_brush_maxFaces ) );
}


inline PlaneClassification Winding_ClassifyDistance( const double distance, const double epsilon ){
	if ( distance > epsilon ) {
		return ePlaneFront;
	}
	if ( distance < -epsilon ) {
		return ePlaneBack;
	}
	return ePlaneOn;
}

/// \brief Returns true if
/// !flipped && winding is completely BACK or ON
/// or flipped && winding is completely FRONT or ON
bool Winding_TestPlane( const Winding& winding, const Plane3& plane, bool flipped ){
	const int test = ( flipped ) ? ePlaneBack : ePlaneFront;
	for ( Winding::const_iterator i = winding.begin(); i != winding.end(); ++i )
	{
		if ( test == Winding_ClassifyDistance( plane3_distance_to_point( plane, ( *i ).vertex ), ON_EPSILON ) ) {
			return false;
		}
	}
	return true;
}

/// \brief Returns true if any point in \p w1 is in front of plane2, or any point in \p w2 is in front of plane1
bool Winding_PlanesConcave( const Winding& w1, const Winding& w2, const Plane3& plane1, const Plane3& plane2 ){
	return !Winding_TestPlane( w1, plane2, false ) || !Winding_TestPlane( w2, plane1, false );
}

brushsplit_t Winding_ClassifyPlane( const Winding& winding, const Plane3& plane ){
	brushsplit_t split;
	for ( Winding::const_iterator i = winding.begin(); i != winding.end(); ++i )
	{
		++split.counts[Winding_ClassifyDistance( plane3_distance_to_point( plane, ( *i ).vertex ), ON_EPSILON )];
	}
	return split;
}


#define DEBUG_EPSILON ON_EPSILON
const double DEBUG_EPSILON_SQUARED = DEBUG_EPSILON * DEBUG_EPSILON;

#define WINDING_DEBUG 0

/// \brief Clip \p winding which lies on \p plane by \p clipPlane, resulting in \p clipped.
/// If \p winding is completely in front of the plane, \p clipped will be identical to \p winding.
/// If \p winding is completely in back of the plane, \p clipped will be empty.
/// If \p winding intersects the plane, the edge of \p clipped which lies on \p clipPlane will store the value of \p adjacent.
void Winding_Clip( const FixedWinding& winding, const Plane3& plane, const Plane3& clipPlane, std::size_t adjacent, FixedWinding& clipped ){
	PlaneClassification classification = Winding_ClassifyDistance( plane3_distance_to_point( clipPlane, winding.back().vertex ), ON_EPSILON );
	PlaneClassification nextClassification;
	// for each edge
	for ( std::size_t next = 0, i = winding.size() - 1; next != winding.size(); i = next, ++next, classification = nextClassification )
	{
		nextClassification = Winding_ClassifyDistance( plane3_distance_to_point( clipPlane, winding[next].vertex ), ON_EPSILON );
		const FixedWindingVertex& vertex = winding[i];

		// if first vertex of edge is ON
		if ( classification == ePlaneOn ) {
			// append first vertex to output winding
			if ( nextClassification == ePlaneBack ) {
				// this edge lies on the clip plane
				clipped.push_back( FixedWindingVertex( vertex.vertex, plane3_intersect_plane3( plane, clipPlane ), adjacent ) );
			}
			else
			{
				clipped.push_back( vertex );
			}
			continue;
		}

		// if first vertex of edge is FRONT
		if ( classification == ePlaneFront ) {
			// add first vertex to output winding
			clipped.push_back( vertex );
		}
		// if second vertex of edge is ON
		if ( nextClassification == ePlaneOn ) {
			continue;
		}
		// else if second vertex of edge is same as first
		else if ( nextClassification == classification ) {
			continue;
		}
		// else if first vertex of edge is FRONT and there are only two edges
		else if ( classification == ePlaneFront && winding.size() == 2 ) {
			continue;
		}
		// else first vertex is FRONT and second is BACK or vice versa
		else
		{
			// append intersection point of line and plane to output winding
			DoubleVector3 mid( line_intersect_plane( vertex.edge, clipPlane ) );

			if ( classification == ePlaneFront ) {
				// this edge lies on the clip plane
				clipped.push_back( FixedWindingVertex( mid, plane3_intersect_plane3( plane, clipPlane ), adjacent ) );
			}
			else
			{
				clipped.push_back( FixedWindingVertex( mid, vertex.edge, vertex.adjacent ) );
			}
		}
	}
}

std::size_t Winding_FindAdjacent( const Winding& winding, std::size_t face ){
	for ( std::size_t i = 0; i < winding.numpoints; ++i )
	{
		ASSERT_MESSAGE( winding[i].adjacent != c_brush_maxFaces, "edge connectivity data is invalid" );
		if ( winding[i].adjacent == face ) {
			return i;
		}
	}
	return c_brush_maxFaces;
}

std::size_t Winding_Opposite( const Winding& winding, const std::size_t index, const std::size_t other ){
	ASSERT_MESSAGE( index < winding.numpoints && other < winding.numpoints, "Winding_Opposite: index out of range" );

	double dist_best = 0;
	std::size_t index_best = c_brush_maxFaces;

	Ray edge( ray_for_points( winding[index].vertex, winding[other].vertex ) );

	for ( std::size_t i = 0; i < winding.numpoints; ++i )
	{
		if ( i == index || i == other ) {
			continue;
		}

		double dist_squared = ray_squared_distance_to_point( edge, winding[i].vertex );

		if ( dist_squared > dist_best ) {
			dist_best = dist_squared;
			index_best = i;
		}
	}
	return index_best;
}

std::size_t Winding_Opposite( const Winding& winding, const std::size_t index ){
	return Winding_Opposite( winding, index, Winding_next( winding, index ) );
}

/// \brief Calculate the \p centroid of the polygon defined by \p winding which lies on plane \p plane.
void Winding_Centroid( const Winding& winding, const Plane3& plane, Vector3& centroid ){
	double area2 = 0, x_sum = 0, y_sum = 0;
	const ProjectionAxis axis = projectionaxis_for_normal( plane.normal() );
	const indexremap_t remap = indexremap_for_projectionaxis( axis );
	for ( std::size_t i = winding.numpoints - 1, j = 0; j < winding.numpoints; i = j, ++j )
	{
		const double ai = winding[i].vertex[remap.x] * winding[j].vertex[remap.y] - winding[j].vertex[remap.x] * winding[i].vertex[remap.y];
		area2 += ai;
		x_sum += ( winding[j].vertex[remap.x] + winding[i].vertex[remap.x] ) * ai;
		y_sum += ( winding[j].vertex[remap.y] + winding[i].vertex[remap.y] ) * ai;
	}

	centroid[remap.x] = static_cast<float>( x_sum / ( 3 * area2 ) );
	centroid[remap.y] = static_cast<float>( y_sum / ( 3 * area2 ) );
	{
		Ray ray( Vector3( 0, 0, 0 ), Vector3( 0, 0, 0 ) );
		ray.origin[remap.x] = centroid[remap.x];
		ray.origin[remap.y] = centroid[remap.y];
		ray.direction[remap.z] = 1;
		centroid[remap.z] = static_cast<float>( ray_distance_to_plane( ray, plane ) );
	}
}