Romain Guy | a32d100 | 2009-07-31 15:33:59 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2009 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package android.util; |
| 18 | |
| 19 | import java.util.Random; |
| 20 | |
| 21 | /** |
| 22 | * A class that contains utility methods related to numbers. |
ztenghui | 9af77a4c | 2015-04-01 16:38:44 -0700 | [diff] [blame] | 23 | * |
Romain Guy | a32d100 | 2009-07-31 15:33:59 -0700 | [diff] [blame] | 24 | * @hide Pending API council approval |
| 25 | */ |
| 26 | public final class MathUtils { |
| 27 | private static final Random sRandom = new Random(); |
| 28 | private static final float DEG_TO_RAD = 3.1415926f / 180.0f; |
| 29 | private static final float RAD_TO_DEG = 180.0f / 3.1415926f; |
| 30 | |
| 31 | private MathUtils() { |
| 32 | } |
| 33 | |
| 34 | public static float abs(float v) { |
ztenghui | 9af77a4c | 2015-04-01 16:38:44 -0700 | [diff] [blame] | 35 | return v > 0 ? v : -v; |
Romain Guy | a32d100 | 2009-07-31 15:33:59 -0700 | [diff] [blame] | 36 | } |
| 37 | |
| 38 | public static int constrain(int amount, int low, int high) { |
| 39 | return amount < low ? low : (amount > high ? high : amount); |
| 40 | } |
| 41 | |
Jeff Sharkey | ac3fcb1 | 2012-05-02 18:11:52 -0700 | [diff] [blame] | 42 | public static long constrain(long amount, long low, long high) { |
| 43 | return amount < low ? low : (amount > high ? high : amount); |
| 44 | } |
| 45 | |
Romain Guy | a32d100 | 2009-07-31 15:33:59 -0700 | [diff] [blame] | 46 | public static float constrain(float amount, float low, float high) { |
| 47 | return amount < low ? low : (amount > high ? high : amount); |
| 48 | } |
| 49 | |
| 50 | public static float log(float a) { |
| 51 | return (float) Math.log(a); |
| 52 | } |
| 53 | |
| 54 | public static float exp(float a) { |
| 55 | return (float) Math.exp(a); |
| 56 | } |
| 57 | |
| 58 | public static float pow(float a, float b) { |
| 59 | return (float) Math.pow(a, b); |
| 60 | } |
| 61 | |
| 62 | public static float max(float a, float b) { |
| 63 | return a > b ? a : b; |
| 64 | } |
| 65 | |
| 66 | public static float max(int a, int b) { |
| 67 | return a > b ? a : b; |
| 68 | } |
| 69 | |
| 70 | public static float max(float a, float b, float c) { |
| 71 | return a > b ? (a > c ? a : c) : (b > c ? b : c); |
| 72 | } |
| 73 | |
| 74 | public static float max(int a, int b, int c) { |
| 75 | return a > b ? (a > c ? a : c) : (b > c ? b : c); |
| 76 | } |
| 77 | |
| 78 | public static float min(float a, float b) { |
| 79 | return a < b ? a : b; |
| 80 | } |
| 81 | |
| 82 | public static float min(int a, int b) { |
| 83 | return a < b ? a : b; |
| 84 | } |
| 85 | |
| 86 | public static float min(float a, float b, float c) { |
| 87 | return a < b ? (a < c ? a : c) : (b < c ? b : c); |
| 88 | } |
| 89 | |
| 90 | public static float min(int a, int b, int c) { |
| 91 | return a < b ? (a < c ? a : c) : (b < c ? b : c); |
| 92 | } |
| 93 | |
| 94 | public static float dist(float x1, float y1, float x2, float y2) { |
| 95 | final float x = (x2 - x1); |
| 96 | final float y = (y2 - y1); |
Neil Fuller | 33253a4 | 2014-10-01 11:55:10 +0100 | [diff] [blame] | 97 | return (float) Math.hypot(x, y); |
Romain Guy | a32d100 | 2009-07-31 15:33:59 -0700 | [diff] [blame] | 98 | } |
| 99 | |
| 100 | public static float dist(float x1, float y1, float z1, float x2, float y2, float z2) { |
| 101 | final float x = (x2 - x1); |
| 102 | final float y = (y2 - y1); |
| 103 | final float z = (z2 - z1); |
| 104 | return (float) Math.sqrt(x * x + y * y + z * z); |
| 105 | } |
| 106 | |
| 107 | public static float mag(float a, float b) { |
Neil Fuller | 33253a4 | 2014-10-01 11:55:10 +0100 | [diff] [blame] | 108 | return (float) Math.hypot(a, b); |
Romain Guy | a32d100 | 2009-07-31 15:33:59 -0700 | [diff] [blame] | 109 | } |
| 110 | |
| 111 | public static float mag(float a, float b, float c) { |
| 112 | return (float) Math.sqrt(a * a + b * b + c * c); |
| 113 | } |
| 114 | |
| 115 | public static float sq(float v) { |
| 116 | return v * v; |
| 117 | } |
| 118 | |
ztenghui | 9af77a4c | 2015-04-01 16:38:44 -0700 | [diff] [blame] | 119 | public static float dot(float v1x, float v1y, float v2x, float v2y) { |
| 120 | return v1x * v2x + v1y * v2y; |
| 121 | } |
| 122 | |
| 123 | public static float cross(float v1x, float v1y, float v2x, float v2y) { |
| 124 | return v1x * v2y - v1y * v2x; |
| 125 | } |
| 126 | |
Romain Guy | a32d100 | 2009-07-31 15:33:59 -0700 | [diff] [blame] | 127 | public static float radians(float degrees) { |
| 128 | return degrees * DEG_TO_RAD; |
| 129 | } |
| 130 | |
Romain Guy | a9d2d5e | 2009-08-09 17:04:54 -0700 | [diff] [blame] | 131 | public static float degrees(float radians) { |
Romain Guy | a32d100 | 2009-07-31 15:33:59 -0700 | [diff] [blame] | 132 | return radians * RAD_TO_DEG; |
| 133 | } |
| 134 | |
| 135 | public static float acos(float value) { |
| 136 | return (float) Math.acos(value); |
| 137 | } |
| 138 | |
| 139 | public static float asin(float value) { |
| 140 | return (float) Math.asin(value); |
| 141 | } |
| 142 | |
| 143 | public static float atan(float value) { |
| 144 | return (float) Math.atan(value); |
| 145 | } |
| 146 | |
| 147 | public static float atan2(float a, float b) { |
| 148 | return (float) Math.atan2(a, b); |
| 149 | } |
| 150 | |
| 151 | public static float tan(float angle) { |
| 152 | return (float) Math.tan(angle); |
ztenghui | 9af77a4c | 2015-04-01 16:38:44 -0700 | [diff] [blame] | 153 | } |
Romain Guy | a32d100 | 2009-07-31 15:33:59 -0700 | [diff] [blame] | 154 | |
| 155 | public static float lerp(float start, float stop, float amount) { |
| 156 | return start + (stop - start) * amount; |
| 157 | } |
ztenghui | 9af77a4c | 2015-04-01 16:38:44 -0700 | [diff] [blame] | 158 | |
Alan Viverette | 2b4dc11 | 2015-10-02 15:29:43 -0400 | [diff] [blame] | 159 | /** |
| 160 | * Returns an interpolated angle in degrees between a set of start and end |
| 161 | * angles. |
| 162 | * <p> |
| 163 | * Unlike {@link #lerp(float, float, float)}, the direction and distance of |
| 164 | * travel is determined by the shortest angle between the start and end |
| 165 | * angles. For example, if the starting angle is 0 and the ending angle is |
| 166 | * 350, then the interpolated angle will be in the range [0,-10] rather |
| 167 | * than [0,350]. |
| 168 | * |
| 169 | * @param start the starting angle in degrees |
| 170 | * @param end the ending angle in degrees |
| 171 | * @param amount the position between start and end in the range [0,1] |
| 172 | * where 0 is the starting angle and 1 is the ending angle |
| 173 | * @return the interpolated angle in degrees |
| 174 | */ |
| 175 | public static float lerpDeg(float start, float end, float amount) { |
| 176 | final float minAngle = (((end - start) + 180) % 360) - 180; |
| 177 | return minAngle * amount + start; |
| 178 | } |
| 179 | |
Romain Guy | e85c5aa | 2009-08-12 15:23:56 -0700 | [diff] [blame] | 180 | public static float norm(float start, float stop, float value) { |
| 181 | return (value - start) / (stop - start); |
| 182 | } |
ztenghui | 9af77a4c | 2015-04-01 16:38:44 -0700 | [diff] [blame] | 183 | |
Romain Guy | e85c5aa | 2009-08-12 15:23:56 -0700 | [diff] [blame] | 184 | public static float map(float minStart, float minStop, float maxStart, float maxStop, float value) { |
| 185 | return maxStart + (maxStart - maxStop) * ((value - minStart) / (minStop - minStart)); |
| 186 | } |
| 187 | |
Romain Guy | a32d100 | 2009-07-31 15:33:59 -0700 | [diff] [blame] | 188 | public static int random(int howbig) { |
| 189 | return (int) (sRandom.nextFloat() * howbig); |
| 190 | } |
| 191 | |
| 192 | public static int random(int howsmall, int howbig) { |
| 193 | if (howsmall >= howbig) return howsmall; |
| 194 | return (int) (sRandom.nextFloat() * (howbig - howsmall) + howsmall); |
| 195 | } |
ztenghui | 9af77a4c | 2015-04-01 16:38:44 -0700 | [diff] [blame] | 196 | |
Romain Guy | a32d100 | 2009-07-31 15:33:59 -0700 | [diff] [blame] | 197 | public static float random(float howbig) { |
| 198 | return sRandom.nextFloat() * howbig; |
| 199 | } |
| 200 | |
| 201 | public static float random(float howsmall, float howbig) { |
| 202 | if (howsmall >= howbig) return howsmall; |
| 203 | return sRandom.nextFloat() * (howbig - howsmall) + howsmall; |
| 204 | } |
| 205 | |
| 206 | public static void randomSeed(long seed) { |
| 207 | sRandom.setSeed(seed); |
| 208 | } |
Adam Lesinski | 1619ed4 | 2015-09-22 13:02:09 -0700 | [diff] [blame] | 209 | |
| 210 | /** |
| 211 | * Returns the sum of the two parameters, or throws an exception if the resulting sum would |
| 212 | * cause an overflow or underflow. |
| 213 | * @throws IllegalArgumentException when overflow or underflow would occur. |
| 214 | */ |
| 215 | public static int addOrThrow(int a, int b) throws IllegalArgumentException { |
| 216 | if (b == 0) { |
| 217 | return a; |
| 218 | } |
| 219 | |
| 220 | if (b > 0 && a <= (Integer.MAX_VALUE - b)) { |
| 221 | return a + b; |
| 222 | } |
| 223 | |
| 224 | if (b < 0 && a >= (Integer.MIN_VALUE - b)) { |
| 225 | return a + b; |
| 226 | } |
| 227 | throw new IllegalArgumentException("Addition overflow: " + a + " + " + b); |
| 228 | } |
Romain Guy | a32d100 | 2009-07-31 15:33:59 -0700 | [diff] [blame] | 229 | } |