1 2 /* 3 * Copyright 2010 Google Inc. 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 9 10 11 #ifndef GrRandom_DEFINED 12 #define GrRandom_DEFINED 13 14 class GrRandom { 15 public: 16 GrRandom() : fSeed(0) {} 17 GrRandom(uint32_t seed) : fSeed(seed) {} 18 19 uint32_t seed() const { return fSeed; } 20 21 uint32_t nextU() { 22 fSeed = fSeed * kMUL + kADD; 23 return fSeed; 24 } 25 26 int32_t nextS() { return (int32_t)this->nextU(); } 27 28 /** 29 * Returns value [0...1) as a float 30 */ 31 float nextF() { 32 // const is 1 / (2^32 - 1) 33 return (float)(this->nextU() * 2.32830644e-10); 34 } 35 36 /** 37 * Returns value [min...max) as a float 38 */ 39 float nextF(float min, float max) { 40 return min + this->nextF() * (max - min); 41 } 42 43 private: 44 /* 45 * These constants taken from "Numerical Recipes in C", reprinted 1999 46 */ 47 enum { 48 kMUL = 1664525, 49 kADD = 1013904223 50 }; 51 uint32_t fSeed; 52 }; 53 54 #endif 55 56
