252 lines
6.5 KiB
C++
252 lines
6.5 KiB
C++
/*
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Copyright (C) 2001-2006, William Joseph.
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All Rights Reserved.
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This file is part of GtkRadiant.
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GtkRadiant is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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GtkRadiant is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GtkRadiant; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#if !defined( INCLUDED_MATH_CURVE_H )
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#define INCLUDED_MATH_CURVE_H
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/// \file
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/// \brief Curve data types and related operations.
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#include "debugging/debugging.h"
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#include "container/array.h"
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#include <math/matrix.h>
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template<typename I, typename Degree>
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struct BernsteinPolynomial
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{
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static double apply( double t ){
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return 1; // general case not implemented
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}
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};
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typedef IntegralConstant<0> Zero;
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typedef IntegralConstant<1> One;
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typedef IntegralConstant<2> Two;
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typedef IntegralConstant<3> Three;
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typedef IntegralConstant<4> Four;
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template<>
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struct BernsteinPolynomial<Zero, Zero>
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{
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static double apply( double t ){
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return 1;
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}
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};
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template<>
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struct BernsteinPolynomial<Zero, One>
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{
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static double apply( double t ){
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return 1 - t;
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}
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};
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template<>
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struct BernsteinPolynomial<One, One>
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{
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static double apply( double t ){
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return t;
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}
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};
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template<>
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struct BernsteinPolynomial<Zero, Two>
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{
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static double apply( double t ){
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return ( 1 - t ) * ( 1 - t );
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}
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};
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template<>
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struct BernsteinPolynomial<One, Two>
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{
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static double apply( double t ){
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return 2 * ( 1 - t ) * t;
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}
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};
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template<>
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struct BernsteinPolynomial<Two, Two>
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{
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static double apply( double t ){
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return t * t;
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}
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};
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template<>
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struct BernsteinPolynomial<Zero, Three>
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{
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static double apply( double t ){
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return ( 1 - t ) * ( 1 - t ) * ( 1 - t );
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}
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};
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template<>
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struct BernsteinPolynomial<One, Three>
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{
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static double apply( double t ){
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return 3 * ( 1 - t ) * ( 1 - t ) * t;
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}
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};
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template<>
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struct BernsteinPolynomial<Two, Three>
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{
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static double apply( double t ){
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return 3 * ( 1 - t ) * t * t;
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}
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};
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template<>
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struct BernsteinPolynomial<Three, Three>
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{
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static double apply( double t ){
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return t * t * t;
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}
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};
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typedef Array<Vector3> ControlPoints;
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inline Vector3 CubicBezier_evaluate( const Vector3* firstPoint, double t ){
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Vector3 result( 0, 0, 0 );
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double denominator = 0;
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{
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double weight = BernsteinPolynomial<Zero, Three>::apply( t );
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result += vector3_scaled( *firstPoint++, weight );
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denominator += weight;
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}
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{
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double weight = BernsteinPolynomial<One, Three>::apply( t );
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result += vector3_scaled( *firstPoint++, weight );
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denominator += weight;
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}
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{
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double weight = BernsteinPolynomial<Two, Three>::apply( t );
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result += vector3_scaled( *firstPoint++, weight );
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denominator += weight;
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}
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{
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double weight = BernsteinPolynomial<Three, Three>::apply( t );
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result += vector3_scaled( *firstPoint++, weight );
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denominator += weight;
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}
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return result / denominator;
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}
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inline Vector3 CubicBezier_evaluateMid( const Vector3* firstPoint ){
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return vector3_scaled( firstPoint[0], 0.125 )
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+ vector3_scaled( firstPoint[1], 0.375 )
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+ vector3_scaled( firstPoint[2], 0.375 )
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+ vector3_scaled( firstPoint[3], 0.125 );
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}
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inline Vector3 CatmullRom_evaluate( const ControlPoints& controlPoints, double t ){
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// scale t to be segment-relative
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t *= double(controlPoints.size() - 1);
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// subtract segment index;
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std::size_t segment = 0;
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for ( std::size_t i = 0; i < controlPoints.size() - 1; ++i )
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{
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if ( t <= double(i + 1) ) {
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segment = i;
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break;
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}
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}
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t -= segment;
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const double reciprocal_alpha = 1.0 / 3.0;
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Vector3 bezierPoints[4];
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bezierPoints[0] = controlPoints[segment];
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bezierPoints[1] = ( segment > 0 )
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? controlPoints[segment] + vector3_scaled( controlPoints[segment + 1] - controlPoints[segment - 1], reciprocal_alpha * 0.5 )
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: controlPoints[segment] + vector3_scaled( controlPoints[segment + 1] - controlPoints[segment], reciprocal_alpha );
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bezierPoints[2] = ( segment < controlPoints.size() - 2 )
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? controlPoints[segment + 1] + vector3_scaled( controlPoints[segment] - controlPoints[segment + 2], reciprocal_alpha * 0.5 )
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: controlPoints[segment + 1] + vector3_scaled( controlPoints[segment] - controlPoints[segment + 1], reciprocal_alpha );
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bezierPoints[3] = controlPoints[segment + 1];
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return CubicBezier_evaluate( bezierPoints, t );
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}
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typedef Array<float> Knots;
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inline double BSpline_basis( const Knots& knots, std::size_t i, std::size_t degree, double t ){
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if ( degree == 0 ) {
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if ( knots[i] <= t
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&& t < knots[i + 1]
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&& knots[i] < knots[i + 1] ) {
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return 1;
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}
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return 0;
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}
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double leftDenom = knots[i + degree] - knots[i];
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double left = ( leftDenom == 0 ) ? 0 : ( ( t - knots[i] ) / leftDenom ) * BSpline_basis( knots, i, degree - 1, t );
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double rightDenom = knots[i + degree + 1] - knots[i + 1];
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double right = ( rightDenom == 0 ) ? 0 : ( ( knots[i + degree + 1] - t ) / rightDenom ) * BSpline_basis( knots, i + 1, degree - 1, t );
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return left + right;
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}
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inline Vector3 BSpline_evaluate( const ControlPoints& controlPoints, const Knots& knots, std::size_t degree, double t ){
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Vector3 result( 0, 0, 0 );
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for ( std::size_t i = 0; i < controlPoints.size(); ++i )
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{
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result += vector3_scaled( controlPoints[i], BSpline_basis( knots, i, degree, t ) );
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}
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return result;
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}
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typedef Array<float> NURBSWeights;
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inline Vector3 NURBS_evaluate( const ControlPoints& controlPoints, const NURBSWeights& weights, const Knots& knots, std::size_t degree, double t ){
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Vector3 result( 0, 0, 0 );
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double denominator = 0;
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for ( std::size_t i = 0; i < controlPoints.size(); ++i )
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{
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double weight = weights[i] * BSpline_basis( knots, i, degree, t );
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result += vector3_scaled( controlPoints[i], weight );
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denominator += weight;
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}
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return result / denominator;
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}
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inline void KnotVector_openUniform( Knots& knots, std::size_t count, std::size_t degree ){
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knots.resize( count + degree + 1 );
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std::size_t equalKnots = 1;
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for ( std::size_t i = 0; i < equalKnots; ++i )
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{
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knots[i] = 0;
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knots[knots.size() - ( i + 1 )] = 1;
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}
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std::size_t difference = knots.size() - 2 * ( equalKnots );
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for ( std::size_t i = 0; i < difference; ++i )
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{
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knots[i + equalKnots] = Knots::value_type( double(i + 1) * 1.0 / double(difference + 1) );
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}
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}
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#endif
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