org.jbox2d.common.MathUtils Maven / Gradle / Ivy
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* Copyright (c) 2013, Daniel Murphy
* All rights reserved.
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/*
* JBox2D - A Java Port of Erin Catto's Box2D
*
* JBox2D homepage: http://jbox2d.sourceforge.net/
* Box2D homepage: http://www.box2d.org
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
package org.jbox2d.common;
import java.util.Random;
/**
* A few math methods that don't fit very well anywhere else.
*/
public class MathUtils extends PlatformMathUtils {
public static final float PI = (float) Math.PI;
public static final float TWOPI = (float) (Math.PI * 2);
public static final float INV_PI = 1f / PI;
public static final float HALF_PI = PI / 2;
public static final float QUARTER_PI = PI / 4;
public static final float THREE_HALVES_PI = TWOPI - HALF_PI;
/**
* Degrees to radians conversion factor
*/
public static final float DEG2RAD = PI / 180;
/**
* Radians to degrees conversion factor
*/
public static final float RAD2DEG = 180 / PI;
public static final float[] sinLUT = new float[Settings.SINCOS_LUT_LENGTH];
static {
for (int i = 0; i < Settings.SINCOS_LUT_LENGTH; i++) {
sinLUT[i] = (float) Math.sin(i * Settings.SINCOS_LUT_PRECISION);
}
}
public static final float sin(float x) {
if (Settings.SINCOS_LUT_ENABLED) {
return sinLUT(x);
} else {
return (float) StrictMath.sin(x);
}
}
public static final float sinLUT(float x) {
x %= TWOPI;
if (x < 0) {
x += TWOPI;
}
if (Settings.SINCOS_LUT_LERP) {
x /= Settings.SINCOS_LUT_PRECISION;
final int index = (int) x;
if (index != 0) {
x %= index;
}
// the next index is 0
if (index == Settings.SINCOS_LUT_LENGTH - 1) {
return ((1 - x) * sinLUT[index] + x * sinLUT[0]);
} else {
return ((1 - x) * sinLUT[index] + x * sinLUT[index + 1]);
}
} else {
return sinLUT[MathUtils.round(x / Settings.SINCOS_LUT_PRECISION) % Settings.SINCOS_LUT_LENGTH];
}
}
public static final float cos(float x) {
if (Settings.SINCOS_LUT_ENABLED) {
return sinLUT(HALF_PI - x);
} else {
return (float) StrictMath.cos(x);
}
}
public static final float abs(final float x) {
if (Settings.FAST_ABS) {
return x > 0 ? x : -x;
} else {
return StrictMath.abs(x);
}
}
public static final float fastAbs(final float x) {
return x > 0 ? x : -x;
}
public static final int abs(int x) {
int y = x >> 31;
return (x ^ y) - y;
}
public static final int floor(final float x) {
if (Settings.FAST_FLOOR) {
return fastFloor(x);
} else {
return (int) StrictMath.floor(x);
}
}
public static final int fastFloor(final float x) {
int y = (int) x;
if (x < y) {
return y - 1;
}
return y;
}
public static final int ceil(final float x) {
if (Settings.FAST_CEIL) {
return fastCeil(x);
} else {
return (int) StrictMath.ceil(x);
}
}
public static final int fastCeil(final float x) {
int y = (int) x;
if (x > y) {
return y + 1;
}
return y;
}
public static final int round(final float x) {
if (Settings.FAST_ROUND) {
return floor(x + .5f);
} else {
return StrictMath.round(x);
}
}
/**
* Rounds up the value to the nearest higher power^2 value.
*
* @param x
* @return power^2 value
*/
public static final int ceilPowerOf2(int x) {
int pow2 = 1;
while (pow2 < x) {
pow2 <<= 1;
}
return pow2;
}
public final static float max(final float a, final float b) {
return a > b ? a : b;
}
public final static int max(final int a, final int b) {
return a > b ? a : b;
}
public final static float min(final float a, final float b) {
return a < b ? a : b;
}
public final static int min(final int a, final int b) {
return a < b ? a : b;
}
public final static float map(final float val, final float fromMin, final float fromMax,
final float toMin, final float toMax) {
final float mult = (val - fromMin) / (fromMax - fromMin);
final float res = toMin + mult * (toMax - toMin);
return res;
}
/** Returns the closest value to 'a' that is in between 'low' and 'high' */
public final static float clamp(final float a, final float low, final float high) {
return max(low, min(a, high));
}
public final static Vec2 clamp(final Vec2 a, final Vec2 low, final Vec2 high) {
final Vec2 min = new Vec2();
min.x = a.x < high.x ? a.x : high.x;
min.y = a.y < high.y ? a.y : high.y;
min.x = low.x > min.x ? low.x : min.x;
min.y = low.y > min.y ? low.y : min.y;
return min;
}
public final static void clampToOut(final Vec2 a, final Vec2 low, final Vec2 high, final Vec2 dest) {
dest.x = a.x < high.x ? a.x : high.x;
dest.y = a.y < high.y ? a.y : high.y;
dest.x = low.x > dest.x ? low.x : dest.x;
dest.y = low.y > dest.y ? low.y : dest.y;
}
/**
* Next Largest Power of 2: Given a binary integer value x, the next largest power of 2 can be
* computed by a SWAR algorithm that recursively "folds" the upper bits into the lower bits. This
* process yields a bit vector with the same most significant 1 as x, but all 1's below it. Adding
* 1 to that value yields the next largest power of 2.
*/
public final static int nextPowerOfTwo(int x) {
x |= x >> 1;
x |= x >> 2;
x |= x >> 4;
x |= x >> 8;
x |= x >> 16;
return x + 1;
}
public final static boolean isPowerOfTwo(final int x) {
return x > 0 && (x & x - 1) == 0;
}
public static final float pow(float a, float b) {
if (Settings.FAST_POW) {
return fastPow(a, b);
} else {
return (float) StrictMath.pow(a, b);
}
}
public static final float atan2(final float y, final float x) {
if (Settings.FAST_ATAN2) {
return fastAtan2(y, x);
} else {
return (float) StrictMath.atan2(y, x);
}
}
public static final float fastAtan2(float y, float x) {
if (x == 0.0f) {
if (y > 0.0f) return HALF_PI;
if (y == 0.0f) return 0.0f;
return -HALF_PI;
}
float atan;
final float z = y / x;
if (abs(z) < 1.0f) {
atan = z / (1.0f + 0.28f * z * z);
if (x < 0.0f) {
if (y < 0.0f) return atan - PI;
return atan + PI;
}
} else {
atan = HALF_PI - z / (z * z + 0.28f);
if (y < 0.0f) return atan - PI;
}
return atan;
}
public static final float reduceAngle(float theta) {
theta %= TWOPI;
if (abs(theta) > PI) {
theta = theta - TWOPI;
}
if (abs(theta) > HALF_PI) {
theta = PI - theta;
}
return theta;
}
public static final float randomFloat(float argLow, float argHigh) {
return (float) Math.random() * (argHigh - argLow) + argLow;
}
public static final float randomFloat(Random r, float argLow, float argHigh) {
return r.nextFloat() * (argHigh - argLow) + argLow;
}
public static final float sqrt(float x) {
return (float) StrictMath.sqrt(x);
}
public final static float distanceSquared(Vec2 v1, Vec2 v2) {
float dx = (v1.x - v2.x);
float dy = (v1.y - v2.y);
return dx * dx + dy * dy;
}
public final static float distance(Vec2 v1, Vec2 v2) {
return sqrt(distanceSquared(v1, v2));
}
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