com.bbn.openmap.proj
Class Clip

java.lang.Object
  com.bbn.openmap.proj.Clip

public class Clip
extends java.lang.Object

Clipping functions.

Method Summary

static float[]	liang_clip(int xleft, int xright, int ytop, int ybottom, float[] x, float[] y, int n, float[] ret_val) Liang Barsy polygon clipping algorithm.
static int	liang_get_buflen(int nverts) Calculate the float[] x,y buffer length for nverts.
static int	quickCheckLineClip(int x1, int y1, int x2, int y2, int xleft, int xright, int ytop, int ybottom) Check if a line is completely inside or completely outside viewport.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

liang_get_buflen

public static final int liang_get_buflen(int nverts)

Calculate the float[] x,y buffer length for nverts.

Parameters:

nverts - number of verts

Returns:

int length required

liang_clip

public static final float[] liang_clip(int xleft,
                                       int xright,
                                       int ytop,
                                       int ybottom,
                                       float[] x,
                                       float[] y,
                                       int n,
                                       float[] ret_val)

Liang Barsy polygon clipping algorithm.

Viewport: xleft < xright, ybottom < ytop

Set up with: float[] ret_val = new float[n*2*2]; ret_val = liang_clip(,...,ret_val);

Points: xpoints, ypoints, npts HACK: closure on these points?

Parameters:

xleft - left side of viewport

xright - right side of viewport

ytop - top of viewport

ybottom - bottom of viewport

x - float[] x coords

y - float[] y coords

n - numcoords

ret_val - float[] clipped polygon

See Also:

liang_get_buflen(int)

quickCheckLineClip

public static final int quickCheckLineClip(int x1,
                                           int y1,
                                           int x2,
                                           int y2,
                                           int xleft,
                                           int xright,
                                           int ytop,
                                           int ybottom)

Check if a line is completely inside or completely outside viewport.

Parameters:

x1 - pt1.x

y1 - pt1.y

x2 - pt2.x

y2 - pt2.y

xleft - left

xright - right

ytop - ytop < ybottom

ybottom - ybottom < ytop

Returns:

int -1=outside, 1=inside, 0=undetermined