【发布时间】：2016-07-10 17:24:44
【问题描述】：
嗨，最近我实现了贝塞尔曲线，它工作正常，但我的问题是我不知道如何将 x,y 点映射到屏幕，因为它以小数点的形式给了我 x,y，我将不胜感激 这是我认为有效的代码。
import java.util.ArrayList;
public class Bezier {
public static void main(String[] args) {
ArrayList<Point> CP = new ArrayList<Point>();
CP.add(new Point(-5, 0));
CP.add(new Point(0, 5));
CP.add(new Point(5, 0));
CP.add(new Point(0,-5));
Bezier curve = new Bezier(3, 0, 0.01, CP);
curve.DefineBezierCurve();
ArrayList<Point>Results = curve.getCurvePoints();
for(int i = 0; i<Results.size() ; i++){
Point x = Results.get(i);
System.out.println(x.Y);
}
}
// class definitions
private ArrayList<Point> controlPoints;// the control points
private double t;//the value of t indicates the location of the point on the line sigment
private double step;// the increment value that the t increments
private int N;//the Beziar Curve Order
private ArrayList<Point>CurvePoints;// genrated (x,y) values of the curve
// constructor
public Bezier(int n , double t , double step ,ArrayList<Point> CP ){
this.N = n ;
this.t = t;
this.step = step;
this.controlPoints = CP;
CurvePoints = new ArrayList<Point>();
}
private int factorial(int x){
int result =1;
for(int i= x ; x>0 ; x--){
result*=x;
}
return result;
}
private int BinomialCoefficient(int i){
// we get the order form the global variable
int factN = factorial(this.N);
int factI = factorial(i);
int factN_I = factorial(this.N-i);
int theCoefficient = (factN/(factI*factN_I));
return theCoefficient ;
}
private Point BI_N_P(int i){
int coefficient = BinomialCoefficient(i);
Point CurrentControlPoint = this.controlPoints.get(i);
double X = coefficient* Math.pow(t,i)* Math.pow((1-t),(this.N-i))*CurrentControlPoint.X ;
double Y = coefficient* Math.pow(t,i)* Math.pow((1-t),(this.N-i))*CurrentControlPoint.Y ;
Point Tmp = new Point(X, Y);
return Tmp;
// this.CurvePoints.add(PointOnCrve);
}
private void DefineBezierCurve(){
while(t<=1){
Point PointOnCurve = new Point(0, 0);
for(int i = 0 ; i<=this.N ; i++){
Point tmp = BI_N_P(i);
PointOnCurve.X+=tmp.X;
PointOnCurve.Y+=tmp.Y;
}
this.CurvePoints.add(PointOnCurve);
this.t+=this.step;
}
}
public ArrayList<Point> getCurvePoints(){
return this.CurvePoints;
}
}
class Point{
public double X;
public double Y;
public Point(double x,double y){
X=x;
Y=y;
}
}
三次贝塞尔曲线初始 t=0,step = 0.01 的示例，带有控制点 (-5, 0),(0, 5),(5, 0),(0,-5) 生成X个点
-5.0
-4.85001
-4.700079999999999
-4.55027
-4.400639999999999
-4.25125
-4.102159999999999
-3.9534299999999996
-3.80512
-3.6572900000000006
-3.5100000000000007
-3.3633100000000002
-3.2172800000000006
-3.07197
-2.92744
-2.7837499999999995
-2.6409599999999993
-2.4991299999999996
-2.3583199999999995
-2.2185899999999994
-2.0799999999999996
-1.9426099999999988
-1.8064799999999992
-1.6716699999999989
-1.5382399999999987
-1.4062499999999998
-1.2757599999999993
-1.1468299999999993
-1.0195199999999995
-0.8938899999999995
-0.7699999999999991
-0.6479099999999991
-0.527679999999999
-0.4093699999999989
-0.29303999999999886
-0.17874999999999885
-0.06655999999999862
0.043470000000001674
0.15128000000000164
0.256810000000002
0.3600000000000019
0.4607900000000018
0.5591200000000022
0.6549300000000019
0.7481600000000019
0.838750000000002
0.9266400000000021
1.011770000000002
1.094080000000002
1.173510000000002
1.2500000000000018
1.3234900000000016
1.3939200000000018
1.4612300000000018
1.5253600000000018
1.5862500000000017
1.6438400000000017
1.6980700000000017
1.7488800000000018
1.7962100000000016
1.8400000000000019
1.8801900000000014
1.916720000000001
1.9495300000000007
1.9785600000000012
2.0037500000000006
2.0250400000000006
2.042370000000001
2.05568
2.0649100000000002
2.0700000000000003
2.07089
2.06752
2.0598299999999994
2.0477599999999994
2.031249999999999
2.010239999999999
1.984669999999999
1.9544799999999984
1.9196099999999983
1.8799999999999981
1.8355899999999976
1.7863199999999972
1.7321299999999973
1.672959999999997
1.6087499999999963
1.539439999999996
1.4649699999999957
1.3852799999999954
1.3003099999999952
1.2099999999999946
1.1142899999999942
1.0131199999999938
0.9064299999999934
0.7941599999999929
0.6762499999999925
0.552639999999992
0.4232699999999916
0.28807999999999107
0.14700999999999054
生成的 Y 点
0.0
0.14701
0.28808
0.42327
0.55264
0.6762500000000001
0.79416
0.90643
1.0131200000000002
1.1142900000000002
1.21
1.3003099999999999
1.3852799999999996
1.4649699999999997
1.5394399999999997
1.6087499999999997
1.6729599999999996
1.7321299999999997
1.78632
1.83559
1.88
1.91961
1.95448
1.98467
2.0102400000000005
2.0312500000000004
2.0477600000000002
2.0598300000000003
2.0675200000000005
2.0708900000000003
2.0700000000000003
2.0649100000000002
2.0556800000000006
2.0423700000000005
2.0250400000000006
2.00375
1.9785599999999997
1.9495300000000002
1.91672
1.8801899999999998
1.8399999999999999
1.7962099999999999
1.748879999999999
1.6980699999999993
1.6438399999999993
1.5862499999999993
1.5253599999999992
1.461229999999999
1.3939199999999987
1.3234899999999983
1.2499999999999982
1.173509999999998
1.094079999999998
1.011769999999998
0.9266399999999977
0.8387499999999977
0.7481599999999973
0.6549299999999975
0.5591199999999971
0.46078999999999715
0.359999999999997
0.2568099999999969
0.15127999999999653
0.043469999999996345
-0.06656000000000395
-0.17875000000000396
-0.2930400000000042
-0.40937000000000445
-0.5276800000000048
-0.6479100000000048
-0.7700000000000049
-0.8938900000000052
-1.0195200000000053
-1.1468300000000053
-1.2757600000000053
-1.4062500000000062
-1.538240000000006
-1.6716700000000062
-1.8064800000000063
-1.9426100000000066
-2.0800000000000067
-2.218590000000007
-2.3583200000000066
-2.499130000000007
-2.6409600000000077
-2.783750000000008
-2.927440000000008
-3.0719700000000083
-3.217280000000008
-3.363310000000008
-3.5100000000000087
-3.6572900000000086
-3.805120000000009
-3.9534300000000084
-4.102160000000009
-4.251250000000009
-4.40064000000001
-4.550270000000009
-4.7000800000000105
-4.85001000000001
【问题讨论】：
-
这看起来像是将 double 转换为 int 问题 -_- 吗？？
-
"它工作正常，但我的问题是我不知道如何将 x,y 点映射到屏幕因为它以小数点的形式给了我 x,y"，确实如此。
-
老兄，我知道，但在这里你不能简单地将它转换为 int，必须有一种方法，当你这样做时，结果曲线是一样的，希望它现在清晰
标签： java math interpolation bezier