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- LineClipper added start(x0,y0), clipNext(x1,y1) 'state' clipping mode

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- use vec4 array for extrusion colors -> set color only once for all tiles
- use full range for direction vector in extrusion vertex
This commit is contained in:
Hannes Janetzek
2013-01-06 21:52:10 +01:00
parent e9d2c88022
commit d0ad2f3bd4
3 changed files with 109 additions and 71 deletions
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110
src/org/oscim/utils/LineClipper.java
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@@ -14,8 +14,6 @@
*/
package org.oscim.utils;
import android.graphics.Point;
/**
* @author Hannes Janetzek
* taken from http://en.wikipedia.org/wiki/Cohen%E2%80%93
@@ -24,14 +22,11 @@ import android.graphics.Point;
public class LineClipper {
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
// Compute the bit code for a point (x, y) using the clip rectangle
// bounded diagonally by (xmin, ymin), and (xmax, ymax)
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
private int xmin, xmax, ymin, ymax;
@@ -42,41 +37,71 @@ public class LineClipper {
this.ymax = maxy;
}
public boolean clip(Point p1, Point p2) {
return clip(p1.x, p1.y, p2.x, p2.y);
private int mPrevOutcode;
private int mPrevX;
private int mPrevY;
public void clipStart(int x0, int y0) {
mPrevX = x0;
mPrevY = y0;
int outcode = INSIDE;
if (x0 < xmin)
outcode |= LEFT;
else if (x0 > xmax)
outcode |= RIGHT;
if (y0 < ymin)
outcode |= BOTTOM;
else if (y0 > ymax)
outcode |= TOP;
mPrevOutcode = outcode;
}
public int outCode(int x, int y) {
int code;
public boolean clipNext(int x1, int y1) {
boolean accept;
code = INSIDE; // initialised as being inside of clip window
int outcode = INSIDE;
if (x1 < xmin)
outcode |= LEFT;
else if (x1 > xmax)
outcode |= RIGHT;
if (y1 < ymin)
outcode |= BOTTOM;
else if (y1 > ymax)
outcode |= TOP;
if (x < xmin) // to the left of clip window
code |= LEFT;
else if (x > xmax) // to the right of clip window
code |= RIGHT;
if (y < ymin) // below the clip window
code |= BOTTOM;
else if (y > ymax) // above the clip window
code |= TOP;
if ((mPrevOutcode | outcode) == 0) {
// Bitwise OR is 0. Trivially accept
accept = true;
} else if ((mPrevOutcode & outcode) != 0) {
// Bitwise AND is not 0. Trivially reject
accept = false;
} else {
accept = clip(mPrevX, mPrevY, x1, y1, xmin, ymin, xmax, ymax, mPrevOutcode, outcode);
}
mPrevOutcode = outcode;
mPrevX = x1;
mPrevY = y1;
return code;
return accept;
}
// CohenSutherland clipping algorithm clips a line from
// P0 = (x0, y0) to P1 = (x1, y1) against a rectangle with
// diagonal from (xmin, ymin) to (xmax, ymax).
public boolean clip(int x0, int y0, int x1, int y1) {
// compute outcodes for P0, P1, and whatever point lies outside the clip rectangle
int outcode0 = outCode(x0, y0);
int outcode1 = outCode(x1, y1);
private static boolean clip(int x0, int y0, int x1, int y1,
int xmin, int ymin, int xmax, int ymax, int outcode0, int outcode1) {
boolean accept = false;
while (true) {
if ((outcode0 | outcode1) == 0) { // Bitwise OR is 0. Trivially accept and get out of loop
if ((outcode0 | outcode1) == 0) {
// Bitwise OR is 0. Trivially accept and get out of loop
accept = true;
break;
} else if ((outcode0 & outcode1) != 0) { // Bitwise AND is not 0. Trivially reject and get out of loop
} else if ((outcode0 & outcode1) != 0) {
// Bitwise AND is not 0. Trivially reject and get out of loop
break;
} else {
// failed both tests, so calculate the line segment to clip
@@ -92,32 +117,45 @@ public class LineClipper {
if ((outcodeOut & TOP) != 0) { // point is above the clip rectangle
x = x0 + (x1 - x0) * (ymax - y0) / (y1 - y0);
y = ymax;
} else if ((outcodeOut & BOTTOM) != 0) { // point is below the clip rectangle
} else if ((outcodeOut & BOTTOM) != 0) {
// point is below the clip rectangle
x = x0 + (x1 - x0) * (ymin - y0) / (y1 - y0);
y = ymin;
} else if ((outcodeOut & RIGHT) != 0) { // point is to the right of clip rectangle
} else if ((outcodeOut & RIGHT) != 0) {
// point is to the right of clip rectangle
y = y0 + (y1 - y0) * (xmax - x0) / (x1 - x0);
x = xmax;
} else if ((outcodeOut & LEFT) != 0) { // point is to the left of clip rectangle
} else if ((outcodeOut & LEFT) != 0) {
// point is to the left of clip rectangle
y = y0 + (y1 - y0) * (xmin - x0) / (x1 - x0);
x = xmin;
}
int outcode = INSIDE;
if (x < xmin)
outcode |= LEFT;
else if (x > xmax)
outcode |= RIGHT;
if (y < ymin)
outcode |= BOTTOM;
else if (y > ymax)
outcode |= TOP;
// Now we move outside point to intersection point to clip
// and get ready for next pass.
if (outcodeOut == outcode0) {
x0 = x;
y0 = y;
outcode0 = outCode(x0, y0);
outcode0 = outcode;
} else {
x1 = x;
y1 = y;
outcode1 = outCode(x1, y1);
outcode1 = outcode;
}
}
}
// TODO do sth with the result x0...
// TODO could do sth with the result x0...
return accept;
}