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add TileClipper

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This commit is contained in:
Hannes Janetzek 2013-10-06 21:15:02 +02:00
parent 6a28480510
commit d44489819a
2 changed files with 218 additions and 13 deletions
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23
vtm/src/org/oscim/utils/LineClipper.java
View File

@ -23,11 +23,11 @@ package org.oscim.utils;
public class LineClipper {
private static final int INSIDE = 0; // 0000
private static final int LEFT = 1; // 0001
private static final int RIGHT = 2; // 0010
private static final int BOTTOM = 4; // 0100
private static final int TOP = 8; // 1000
public static final int INSIDE = 0; // 0000
public static final int LEFT = 1; // 0001
public static final int RIGHT = 2; // 0010
public static final int BOTTOM = 4; // 0100
public static final int TOP = 8; // 1000
private final int xmin, xmax, ymin, ymax;
public final int[] out;
@ -62,17 +62,15 @@ public class LineClipper {
mPrevX = x0;
mPrevY = y0;
int outcode = INSIDE;
mPrevOutcode = INSIDE;
if (x0 < xmin)
outcode |= LEFT;
mPrevOutcode |= LEFT;
else if (x0 > xmax)
outcode |= RIGHT;
mPrevOutcode |= RIGHT;
if (y0 < ymin)
outcode |= BOTTOM;
mPrevOutcode |= BOTTOM;
else if (y0 > ymax)
outcode |= TOP;
mPrevOutcode = outcode;
mPrevOutcode |= TOP;
}
/**
@ -135,7 +133,6 @@ public class LineClipper {
// At least one endpoint is outside the clip rectangle; pick it.
int outcodeOut = (outcode0 == 0) ? outcode1 : outcode0;
// Now find the intersection point;
// use formulas y = y0 + slope * (x - x0), x = x0 + (1 / slope) * (y - y0)
if ((outcodeOut & TOP) != 0) { // point is above the clip rectangle

208
vtm/src/org/oscim/utils/TileClipper.java Normal file
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@ -0,0 +1,208 @@
package org.oscim.utils;
import org.oscim.core.GeometryBuffer;
/**
* Clip polygon to a rectangle. Output cannot expected to be valid
* Simple-Feature geometry, i.e. all rings are clipped independently
* so that inner and outer rings might touch, etc.
*
* based on http://www.cs.rit.edu/~icss571/clipTrans/PolyClipBack.html
* */
public class TileClipper {
private float minX;
private float maxX;
private float minY;
private float maxY;
public TileClipper(float minX, float minY, float maxX, float maxY) {
this.minX = minX;
this.minY = minY;
this.maxX = maxX;
this.maxY = maxY;
}
public void setRect(float minX, float minY, float maxX, float maxY) {
this.minX = minX;
this.minY = minY;
this.maxX = maxX;
this.maxY = maxY;
}
private final GeometryBuffer mGeomOut = new GeometryBuffer(10, 1);
public boolean clip(GeometryBuffer geom) {
GeometryBuffer out = mGeomOut;
out.clear();
clipEdge(geom, out, LineClipper.LEFT);
geom.clear();
clipEdge(out, geom, LineClipper.TOP);
out.clear();
clipEdge(geom, out, LineClipper.RIGHT);
geom.clear();
clipEdge(out, geom, LineClipper.BOTTOM);
if ((geom.indexPos == 0) && (geom.index[0] < 6))
return false;
return true;
}
private boolean clipEdge(GeometryBuffer in, GeometryBuffer out, int edge) {
out.startPolygon();
boolean outer = true;
int pointPos = 0;
for (int i = 0, n = in.index.length; i < n; i++) {
int len = in.index[i];
if (len < 0)
break;
if (len < 6) {
pointPos += len;
continue;
}
if (len == 0) {
out.startPolygon();
outer = true;
continue;
}
if (!outer)
out.startHole();
clipRing(i, pointPos, in, out, edge);
// if (out.index[i] < 6) {
// out.index[i] = 0;
// //if (out.indexPos > 0)
// // out.indexPos--;
// // TODO if outer skip holes
// }
pointPos += len;
outer = false;
}
return true;
}
private boolean clipRing(int indexPos, int pointPos, GeometryBuffer in, GeometryBuffer out,
int edge) {
int len = in.index[indexPos];
if (len < 6)
return false;
len += pointPos;
float px = in.points[len - 2];
float py = in.points[len - 1];
for (int i = pointPos; i < len;) {
float cx = in.points[i++];
float cy = in.points[i++];
switch (edge) {
case LineClipper.LEFT:
if (cx > minX) {
// current is inside
if (px > minX) {
// previous was inside
out.addPoint(cx, cy);
} else {
// previous was outside, add edge point
out.addPoint(minX, py + (cy - py) * (minX - px) / (cx - px));
out.addPoint(cx, cy);
}
} else {
if (px > minX) {
// previous was inside, add edge point
out.addPoint(minX, py + (cy - py) * (minX - px) / (cx - px));
}
}
break;
case LineClipper.RIGHT:
if (cx < maxX) {
if (px < maxX) {
out.addPoint(cx, cy);
} else {
out.addPoint(maxX, py + (cy - py) * (maxX - px) / (cx - px));
out.addPoint(cx, cy);
}
} else {
if (px < maxX) {
out.addPoint(maxX, py + (cy - py) * (maxX - px) / (cx - px));
}
}
break;
case LineClipper.BOTTOM:
if (cy > minY) {
if (py > minY) {
out.addPoint(cx, cy);
} else {
out.addPoint(px + (cx - px) * (minY - py) / (cy - py), minY);
out.addPoint(cx, cy);
}
} else {
if (py > minY) {
out.addPoint(px + (cx - px) * (minY - py) / (cy - py), minY);
}
}
break;
case LineClipper.TOP:
if (cy < maxY) {
if (py < maxY) {
out.addPoint(cx, cy);
} else {
out.addPoint(px + (cx - px) * (maxY - py) / (cy - py), maxY);
out.addPoint(cx, cy);
}
} else {
if (py < maxY) {
out.addPoint(px + (cx - px) * (maxY - py) / (cy - py), maxY);
}
}
break;
}
px = cx;
py = cy;
}
return true;
}
// public static void main(String[] args) {
// TileClipper clipper = new TileClipper(0, 0, 100, 100);
// GeometryBuffer geom = new GeometryBuffer(10, 1);
//
// geom.startPolygon();
// geom.addPoint(-10, -10);
// geom.addPoint(110, -10);
// geom.addPoint(110, 110);
// geom.addPoint(-10, 110);
//
// geom.startHole();
// geom.addPoint(10, 10);
// geom.addPoint(110, 10);
// geom.addPoint(110, 90);
// geom.addPoint(10, 90);
//
// System.out.println("" + Arrays.toString(geom.points));
// clipper.clip(geom);
// System.out.println("" + Arrays.toString(geom.points) + " " + geom.index[0]);
//
// }
}