1// Copyright (C) 2011 The Android Open Source Project 2// 3// Licensed under the Apache License, Version 2.0 (the "License"); 4// you may not use this file except in compliance with the License. 5// You may obtain a copy of the License at 6// 7// http://www.apache.org/licenses/LICENSE-2.0 8// 9// Unless required by applicable law or agreed to in writing, software 10// distributed under the License is distributed on an "AS IS" BASIS, 11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12// See the License for the specific language governing permissions and 13// limitations under the License. 14 15#pragma version(1) 16#pragma rs java_package_name(com.android.rs.image) 17 18uint32_t gMaxIteration = 500; 19uint32_t gDimX = 1024; 20uint32_t gDimY = 1024; 21 22float lowerBoundX = -2.f; 23float lowerBoundY = -2.f; 24float scaleFactor = 4.f; 25 26uchar4 __attribute__((kernel)) root(uint32_t x, uint32_t y) { 27 float2 p; 28 p.x = lowerBoundX + ((float)x / gDimX) * scaleFactor; 29 p.y = lowerBoundY + ((float)y / gDimY) * scaleFactor; 30 31 float2 t = 0; 32 float2 t2 = t * t; 33 int iter = 0; 34 while((t2.x + t2.y < 4.f) && (iter < gMaxIteration)) { 35 float xtemp = t2.x - t2.y + p.x; 36 t.y = 2 * t.x * t.y + p.y; 37 t.x = xtemp; 38 iter++; 39 t2 = t * t; 40 } 41 42 if(iter >= gMaxIteration) { 43 // write a non-transparent black pixel 44 return (uchar4){0, 0, 0, 0xff}; 45 } else { 46 float mi3 = gMaxIteration / 3.f; 47 if (iter <= (gMaxIteration / 3)) 48 return (uchar4){0xff * (iter / mi3), 0, 0, 0xff}; 49 else if (iter <= (((gMaxIteration / 3) * 2))) 50 return (uchar4){0xff - (0xff * ((iter - mi3) / mi3)), 51 (0xff * ((iter - mi3) / mi3)), 0, 0xff}; 52 else 53 return (uchar4){0, 0xff - (0xff * ((iter - (mi3 * 2)) / mi3)), 54 (0xff * ((iter - (mi3 * 2)) / mi3)), 0xff}; 55 } 56} 57