/*
* Copyright (c) 2003-onwards Shaven Puppy Ltd
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* * Neither the name of 'Shaven Puppy' nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package worm;
/**
* Some geometry utils ripped out of SPGL-Extra.
* @author Cas
*/
public final class GeomUtil {
public static final int INSIDE = 0;
public static final int SPANNING = 1;
public static final int OUTSIDE = 2;
public static final int CENTER_CENTER = 0x00000000;
public static final int LEFT_CODE = 0x00F00000;
public static final int RIGHT_CODE = 0x000F0000;
public static final int TOP_CODE = 0x0000F000;
public static final int BOTTOM_CODE = 0x00000F00;
/**
* No c'tor
*/
private GeomUtil() {
}
public static boolean rectangleContainsCircle(float x, float y, float radius, float rx, float ry, float width, float height) {
// Treat the circle like an AABB and see if it lies within the bounds
float halfSize = radius / 2f;
float boundsXMax = rx + width;
float boundsYMax = ry + height;
// Left edge
if (x - halfSize < rx) {
return false;
}
// Right edge
if (x + halfSize > boundsXMax) {
return false;
}
// Top edge
if (y - halfSize < boundsYMax) {
return false;
}
if (y + halfSize > ry) {
return false;
}
// All edges ok, circle is within bounding rect
return true;
}
public static int classifyCircle(float x, float y, float radius, float rx, float ry, float width, float height) {
// Totally inside?
if (rectangleContainsCircle(x, y, radius, rx, ry, width, height)) {
return INSIDE;
}
// Totally outside?
int region = findRegionForCircle(x, y, radius, rx, ry, width, height);
if (region != CENTER_CENTER) {
return OUTSIDE;
}
return SPANNING;
}
/** Finds a region code for a circle against this rectangle's bounds
* Outer region codes are returned if the circle is totally within the region.
* Otherwise we return CENTER_CENTER.
*
* NB: This means that CENTER_CENTER could indicate total containment or spanning an edge.
*/
public static int findRegionForCircle(float x, float y, float radius, float rx, float ry, float width, float height) {
int region = CENTER_CENTER;
if (x + radius < rx) {
region |= LEFT_CODE;
} else if (x - radius > rx + width) {
region |= RIGHT_CODE;
}
if (y + radius < ry) {
region |= BOTTOM_CODE;
} else if (y - radius > ry + height) {
region |= TOP_CODE;
}
return region;
}
public static boolean pointInCircle(float x, float y, float radius, float px, float py) {
float dx = px - x;
float dy = py - y;
return Math.sqrt(dx * dx + dy * dy) < radius;
}
public static boolean circleRectCollision(float x, float y, float radius, float rx, float ry, float width, float height) {
// 1. Corners in circle?
if (pointInCircle(x, y, radius, rx, ry)) {
return true;
}
if (pointInCircle(x, y, radius, rx + width, ry)) {
return true;
}
if (pointInCircle(x, y, radius, rx + width, ry + height)) {
return true;
}
if (pointInCircle(x, y, radius, rx, ry + height)) {
return true;
}
// 2. Edge in circle?
if (x >= rx && x < rx + width) {
if (Math.abs(ry - y) < radius) {
return true;
}
if (Math.abs(y - (ry + height)) < radius) {
return true;
}
} else if (y >= ry && y < ry + height) {
if (Math.abs(rx - x) < radius) {
return true;
}
if (Math.abs(x - (rx + width)) < radius) {
return true;
}
}
// 3. Wholly contained?
return x >= rx + radius && y >= ry + radius && x < rx + width - radius && y < ry + height - radius;
}
}