1 /* 2 Copyright 2010 Google Inc. 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 18 #ifndef GrRandom_DEFINED 19 #define GrRandom_DEFINED 20 21 class GrRandom { 22 public: 23 GrRandom() : fSeed(0) {} 24 GrRandom(uint32_t seed) : fSeed(seed) {} 25 26 uint32_t seed() const { return fSeed; } 27 28 uint32_t nextU() { 29 fSeed = fSeed * kMUL + kADD; 30 return fSeed; 31 } 32 33 int32_t nextS() { return (int32_t)this->nextU(); } 34 35 /** 36 * Returns value [0...1) as a float 37 */ 38 float nextF() { 39 // const is 1 / (2^32 - 1) 40 return (float)(this->nextU() * 2.32830644e-10); 41 } 42 43 /** 44 * Returns value [min...max) as a float 45 */ 46 float nextF(float min, float max) { 47 return min + this->nextF() * (max - min); 48 } 49 50 private: 51 /* 52 * These constants taken from "Numerical Recipes in C", reprinted 1999 53 */ 54 enum { 55 kMUL = 1664525, 56 kADD = 1013904223 57 }; 58 uint32_t fSeed; 59 }; 60 61 #endif 62 63
