尝试使用数学旋转多边形

Question

I have a school assignment where I'm supposed to (among other things) rotate a polygon. I can not use any premade rotate functions, so I have an array of points. The array is set up like this:

intArray[2][amount_of_points] where intArray[0] equals the points x coordinate, and intArray[1] holds the y coordinates.

    //x=pivot point x coordinate, y = pivot point y coordinate.
public int[][] rotate(int[][]matrix,int x, int y, double degrees){

    double s=Math.sin(degrees);
    double c=Math.cos(degrees);


    for (int i=0;i<matrix.length;i++){

        //translate to origin
        int px=matrix[0][i]-x;
        int py=matrix[1][i]-y;

        //rotate
        double xnew = (px*c)-(py*s);
        double ynew = (px*s)+(py*c);

        //translate back
        px=(int)((xnew+x)+0.5);
        py=(int)((ynew+y)+0.5);

        matrix[0][i]=px;
        matrix[1][i]=py;
    }

This is my code so far, and it is definitely not working out for me. I tried to trim the code as much as I could. Any help would mean a lot!

edit: I'm not getting any errors when I run the code, no exceptions etc. The only problem is that the polygon isn't rotating the way I intend it to.

I've made a test polygon:

polyArray = new int [2][3];
    polyArray[0][0]=400;
    polyArray[1][0]=200;
    polyArray[0][1]=300;
    polyArray[1][1]=500;
    polyArray[0][2]=500;
    polyArray[1][2]=500;

Which I draw in a JPanel, then I run this array through the rotation method like this: polyArray=mm.rotate(polyArray, polyArray[0][0], polyArray[1][0], Math.PI);

Using the top point as pivotpoint. The whole polygon is then deformed.

Answer 1

Although still not very clear on question, I feel your problem is with the loop. matrix.length is 2 . So, the code never uses these :

polyArray[0][2]=500;
polyArray[1][2]=500;

If you change the condition as below, it should work :

for (int i=0;i<matrix[0].length;i++)