package jhpro.engine3d;

public class MoebiusStrip {

   public static FacetedObject create(int numSegs)
    {
        int numFacets = numSegs;
        int numPoints = numSegs * 2;
        int radius = 50;
        double xr = (int)((double)radius * 1.2D);
        double yr = (int)((double)radius * 0.80000000000000004D);
        double width = 16D;
        double halfWidth = width / 2D;
        double radiansPerSeg = 6.2831853071795862D / (double)(float)numSegs;
        FacetedObject fo = new FacetedObject(numPoints, numFacets, 4);
        for(int i = 0; i < numSegs; i++)
        {
            double theta = (double)i * radiansPerSeg;
            double x;
            double z;
            if(i < numSegs / 2)
            {
                x = halfWidth * Math.sin(theta);
                z = halfWidth * Math.cos(theta);
            } else
            {
                x = 0.0D;
                z = -halfWidth;
            }
            double xm = (xr - x) * Math.cos(theta);
            double xp = (xr + x) * Math.cos(theta);
            double ym = (yr - x) * Math.sin(theta);
            double yp = (yr + x) * Math.sin(theta);
            fo.setPointData(xm, ym, z);
            fo.setPointData(xp, yp, -z);
        }

        int indexPattern[] = {
            0, 2, 3, 1
        };
        int indexPatternEnd[] = {
            numPoints - 2, 1, 0, numPoints - 1
        };
        for(int i = 0; i < numPoints; i += 2)
        {
            for(int j = 0; j < 4; j++)
                fo.setVectorIndex(i >= numPoints - 2 ? indexPatternEnd[j] : i + indexPattern[j]);

        }

        return fo;
    }



}