/*
* Copyright 2013 Hannes Janetzek
*
* This file is part of the OpenScienceMap project (http://www.opensciencemap.org).
*
* This program is free software: you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
* PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License along with
* this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.oscim.utils.geom;
/**
* ported from http://www.flipcode.com/archives/2D_OBB_Intersection.shtml
*/
public class OBB2D {
/**
* Vector math for one array
*/
public static class Vec2 {
public static void set(float[] v, int pos, float x, float y) {
v[pos + 0] = x;
v[pos + 1] = y;
}
public static float dot(float[] v, int a, int b) {
return v[a] * v[b] + v[a + 1] * v[b + 1];
}
public final static float lengthSquared(float[] v, int pos) {
float x = v[pos + 0];
float y = v[pos + 1];
return x * x + y * y;
}
public final static void normalizeSquared(float[] v, int pos) {
float x = v[pos + 0];
float y = v[pos + 1];
float length = x * x + y * y;
v[pos + 0] = x / length;
v[pos + 1] = y / length;
}
public final static void normalize(float[] v, int pos) {
float x = v[pos + 0];
float y = v[pos + 1];
double length = Math.sqrt(x * x + y * y);
v[pos + 0] = (float) (x / length);
v[pos + 1] = (float) (y / length);
}
public final static float length(float[] v, int pos) {
float x = v[pos + 0];
float y = v[pos + 1];
return (float) Math.sqrt(x * x + y * y);
}
public final static void add(float[] v, int r, int a, int b) {
v[r + 0] = v[a + 0] + v[b + 0];
v[r + 1] = v[a + 1] + v[b + 1];
}
public final static void sub(float[] v, int r, int a, int b) {
v[r + 0] = v[a + 0] - v[b + 0];
v[r + 1] = v[a + 1] - v[b + 1];
}
public final static void mul(float[] v, int pos, float a) {
v[pos + 0] *= a;
v[pos + 1] *= a;
}
}
float originX;
float originY;
public final float[] vec = new float[4 * 2 + 2 * 2];
// Corners of the box, where 0 is the lower left.
//public final float[] corner = new float[ 4 * 2];
private final static int CORNER_X = 0;
private final static int CORNER_Y = CORNER_X + 1;
private final static int CORNER_0 = CORNER_X;
private final static int CORNER_1 = CORNER_X + 2;
//private final static int CORNER_2 = CORNER_X + 4;
private final static int CORNER_3 = CORNER_X + 6;
// Two edges of the box extended away from origin[CORNER_X + 0].
//public final float[] axis = new float[2 * 2];
private final static int AXIS_X = 2 * 4;
private final static int AXIS_Y = AXIS_X + 1;
private final static int AXIS_1 = AXIS_X;
private final static int AXIS_2 = AXIS_X + 2;
// Returns true if other overlaps one dimension of this.
private boolean overlaps1Way(OBB2D other) {
for (int a = 0; a <= 2; a += 2) {
float ax = vec[AXIS_X + a];
float ay = vec[AXIS_Y + a];
// dot product
float t = ax * other.vec[CORNER_X] + ay * other.vec[CORNER_Y];
// Find the extent of box 2 on axis a
float tMin = t;
float tMax = t;
for (int c = CORNER_X + 2; c < 8; c += 2) {
t = ax * other.vec[c] + ay * other.vec[c + 1];
if (t < tMin)
tMin = t;
else if (t > tMax)
tMax = t;
}
// We have to subtract off the origin
// See if [tMin, tMax] intersects [0, 1]
if (a == 0) {
if ((tMin > 1 + originX) || (tMax < originX))
// There was no intersection along this dimension;
// the boxes cannot possibly overlap.
return false;
} else {
if ((tMin > 1 + originY) || (tMax < originY))
return false;
}
}
// There was no dimension along which there is no intersection.
// Therefore the boxes overlap.
return true;
}
// Updates the axes after the corners move. Assumes the
// corners actually form a rectangle.
private void computeAxes() {
Vec2.sub(vec, AXIS_1, CORNER_1, CORNER_0);
Vec2.sub(vec, AXIS_2, CORNER_3, CORNER_0);
// Make the length of each axis 1/edge length so we know any
// dot product must be less than 1 to fall within the edge.
Vec2.normalizeSquared(vec, AXIS_1);
originX = Vec2.dot(vec, CORNER_0, AXIS_1);
Vec2.normalizeSquared(vec, AXIS_2);
originY = Vec2.dot(vec, CORNER_0, AXIS_2);
}
// public OBB2D(float cx, float cy, float w, float h, float angle) {
// float rcos = (float) Math.cos(angle);
// float rsin = (float) Math.sin(angle);
//
// float[] tmp = new float[4 * 2];
// Vec2.set(tmp, 0, rcos, rsin);
// Vec2.set(tmp, 1, -rsin, rcos);
//
// Vec2.mul(tmp, 0, w / 2);
// Vec2.mul(tmp, 1, h / 2);
//
// Vec2.add(tmp, 2, tmp, 0, tmp, 1);
// Vec2.sub(tmp, 3, tmp, 0, tmp, 1);
//
// Vec2.set(tmp, 0, cx, cy);
//
// Vec2.sub(origin, CORNER_X + 0, tmp, 0, tmp, 3);
// Vec2.add(origin, CORNER_X + 2, tmp, 0, tmp, 3);
// Vec2.add(origin, CORNER_X + 4, tmp, 0, tmp, 2);
// Vec2.sub(origin, CORNER_X + 6, tmp, 0, tmp, 2);
//
// computeAxes();
// }
//
public OBB2D() {
}
public OBB2D(float cx, float cy, float width, float height, double acos, double asin) {
float vx = (float) acos * width / 2;
float vy = (float) asin * width / 2;
float ux = (float) -asin * height / 2;
float uy = (float) acos * height / 2;
vec[CORNER_X] = cx + (vx - ux);
vec[CORNER_Y] = cy + (vy - uy);
vec[CORNER_X + 2] = cx + (-vx - ux);
vec[CORNER_Y + 2] = cy + (-vy - uy);
vec[CORNER_X + 4] = cx + (-vx + ux);
vec[CORNER_Y + 4] = cy + (-vy + uy);
vec[CORNER_X + 6] = cx + (vx + ux);
vec[CORNER_Y + 6] = cy + (vy + uy);
computeAxes();
}
public void setNormalized(float cx, float cy, float vx, float vy, float width, float height,
float dy) {
float ux = -vy;
float uy = vx;
float hw = width / 2;
float hh = height / 2;
if (dy != 0) {
cx += vx * dy + vy * dy;
cy += -vy * dy + vx * dy;
}
vx *= hw;
vy *= hw;
ux *= hh;
uy *= hh;
vec[CORNER_X] = cx - (vx - ux);
vec[CORNER_Y] = cy - (vy - uy);
vec[CORNER_X + 2] = cx + (vx - ux);
vec[CORNER_Y + 2] = cy + (vy - uy);
vec[CORNER_X + 4] = cx + (vx + ux);
vec[CORNER_Y + 4] = cy + (vy + uy);
vec[CORNER_X + 6] = cx - (vx + ux);
vec[CORNER_Y + 6] = cy - (vy + uy);
computeAxes();
}
public void set(float cx, float cy, float dx, float dy, float width, float height) {
float vx = cx - dx;
float vy = cy - dy;
float a = (float) Math.sqrt(vx * vx + vy * vy);
vx /= a;
vy /= a;
float hw = width / 2;
float hh = height / 2;
float ux = vy * hh;
float uy = -vx * hh;
vx *= hw;
vy *= hw;
vec[CORNER_X] = cx - vx - ux;
vec[CORNER_Y] = cy - vy - uy;
vec[CORNER_X + 2] = cx + vx - ux;
vec[CORNER_Y + 2] = cy + vy - uy;
vec[CORNER_X + 4] = cx + vx + ux;
vec[CORNER_Y + 4] = cy + vy + uy;
vec[CORNER_X + 6] = cx - vx + ux;
vec[CORNER_Y + 6] = cy - vy + uy;
computeAxes();
}
public OBB2D(float cx, float cy, float dx, float dy, float width, float height) {
float vx = cx - dx;
float vy = cy - dy;
float a = (float) Math.sqrt(vx * vx + vy * vy);
vx /= a;
vy /= a;
float hw = width / 2;
float hh = height / 2;
float ux = vy * hh;
float uy = -vx * hh;
vx *= hw;
vy *= hw;
vec[CORNER_X + 0] = cx - vx - ux;
vec[CORNER_Y + 0] = cy - vy - uy;
vec[CORNER_X + 2] = cx + vx - ux;
vec[CORNER_Y + 2] = cy + vy - uy;
vec[CORNER_X + 4] = cx + vx + ux;
vec[CORNER_Y + 4] = cy + vy + uy;
vec[CORNER_X + 6] = cx - vx + ux;
vec[CORNER_Y + 6] = cy - vy + uy;
computeAxes();
}
// width and height must be > 1 I guess
public OBB2D(float cx, float cy, float width, float height) {
float hw = width / 2;
float hh = height / 2;
vec[CORNER_X] = cx - hw;
vec[CORNER_Y] = cy - hh;
vec[CORNER_X + 2] = cx - hw;
vec[CORNER_Y + 2] = cy + hh;
vec[CORNER_X + 4] = cx + hw;
vec[CORNER_Y + 4] = cy + hh;
vec[CORNER_X + 6] = cx + hw;
vec[CORNER_Y + 6] = cy - hh;
vec[AXIS_X + 0] = 0;
vec[AXIS_X + 1] = 1 / height;
vec[AXIS_X + 2] = 1 / width;
vec[AXIS_X + 3] = 0;
vec[0] = vec[CORNER_Y] * vec[AXIS_Y];
vec[1] = vec[CORNER_X + 2] * vec[AXIS_X + 2];
}
// Returns true if the intersection of the boxes is non-empty.
public boolean overlaps(OBB2D other) {
return overlaps1Way(other) && other.overlaps1Way(this);
}
}