Question

嗨最近我实现了bezier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，因为它给了我x，y的小数点形式我会感激任何帮助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;
        }
    }

我使用生成的点在excel中绘制它们，这是我的结果

三次贝塞尔曲线初始t = 0，步长= 0.01的示例，具有控制点（-5,0），（0,5），（5,0），（0，-5）生成X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

Answer 1

将点集乘以某个比例因子，然后舍入为整数。我会建议x的因子Screen Width/MAX(list of x points)和y的Screen Height/MAX(list of y points)。这应该为您提供一个缩放到当前屏幕大小的点列表。这是一些实现这个想法的python代码。

X = "-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"
X = X.split(" ");
absX = list();
for x in X:
    absX.append(abs(float(x)));
max_X = max(absX);
min_X = min(X);
screen_width = 1024;
scale_factor = screen_width/float(max_X + float(max(X)));
newX = list();
for x in X:
    x = int(float(x)*scale_factor) + screen_width;
    newX.append(x)
print(newX);

返回以下X坐标列表：

[300, 322, 344, 366, 387, 409, 430, 452, 473, 495, 516, 537, 559, 580, 601, 621, 642, 663, 683, 703, 723, 743, 763, 782, 802, 821, 840, 858, 877, 895, 913, 931, 948, 965, 982, 999, 1015, 1030, 1045, 1061, 1076, 1090, 1104, 1118, 1132, 1145, 1158, 1170, 1182, 1193, 1205, 1215, 1225, 1235, 1244, 1253, 1262, 1269, 1277, 1284, 1290, 1296, 1301, 1306, 1310, 1314, 1317, 1319, 1321, 1323, 1323, 1323, 1323, 1322, 1320, 1318, 1315, 1311, 1307, 1301, 1296, 1289, 1282, 1274, 1266, 1256, 1246, 1236, 1224, 1212, 1199, 1185, 1170, 1155, 1139, 1121, 1104, 1085, 1065, 1045]

这是Y：

[768, 784, 799, 814, 829, 843, 856, 868, 880, 891, 902, 912, 921, 930, 938, 946, 953, 960, 966, 971, 976, 981, 984, 988, 991, 993, 995, 996, 997, 997, 997, 997, 996, 994, 992, 990, 987, 984, 980, 976, 972, 967, 962, 956, 950, 944, 937, 930, 922, 914, 906, 898, 889, 880, 870, 861, 851, 840, 830, 819, 807, 796, 784, 772, 761, 749, 736, 723, 710, 697, 683, 669, 655, 641, 627, 612, 598, 583, 568, 553, 538, 522, 507, 491, 475, 460, 444, 428, 411, 395, 379, 363, 346, 330, 313, 297, 280, 264, 247, 230]

此脚本并不完美，并且不会返回正确范围内的值，但它应该让您知道从哪里开始。

Bézier曲线图x，y指向屏幕

1 个答案: