1bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma/* 2bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma * Copyright (C) 2012 The Android Open Source Project 3bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma * 4bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma * Licensed under the Apache License, Version 2.0 (the "License"); 5bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma * you may not use this file except in compliance with the License. 6bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma * You may obtain a copy of the License at 7bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma * 8bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma * http://www.apache.org/licenses/LICENSE-2.0 9bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma * 10bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma * Unless required by applicable law or agreed to in writing, software 11bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma * distributed under the License is distributed on an "AS IS" BASIS, 12bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma * See the License for the specific language governing permissions and 14bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma * limitations under the License. 15bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma */ 16bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma 17bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharmars_allocation in_alloc; 18bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharmars_sampler sampler; 19bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma 2050b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharmastatic float2 center, neg_center, inv_dimensions, axis_scale; 2150b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharmastatic float alpha, radius2, factor; 22bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma 2350b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharmavoid init_filter(uint32_t dim_x, uint32_t dim_y, float center_x, float center_y, float k) { 2450b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma center.x = center_x; 2550b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma center.y = center_y; 2650b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma neg_center = -center; 2750b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma inv_dimensions.x = 1.f / (float)dim_x; 2850b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma inv_dimensions.y = 1.f / (float)dim_y; 29d3d6570df4f39af697ba090fa8069aef6acfbcf4Stephen Hines alpha = k * 2.0f + 0.75f; 3050b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma 3150b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma axis_scale = (float2)1.f; 3250b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma if (dim_x > dim_y) 3350b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma axis_scale.y = (float)dim_y / (float)dim_x; 3450b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma else 3550b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma axis_scale.x = (float)dim_x / (float)dim_y; 3650b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma 37d3d6570df4f39af697ba090fa8069aef6acfbcf4Stephen Hines const float bound2 = 0.25f * (axis_scale.x*axis_scale.x + axis_scale.y*axis_scale.y); 38bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma const float bound = sqrt(bound2); 39d3d6570df4f39af697ba090fa8069aef6acfbcf4Stephen Hines const float radius = 1.15f * bound; 40bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma radius2 = radius*radius; 4150b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma const float max_radian = M_PI_2 - atan(alpha / bound * sqrt(radius2 - bound2)); 42bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma factor = bound / max_radian; 43bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma} 44bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma 45d3d6570df4f39af697ba090fa8069aef6acfbcf4Stephen Hinesuchar4 __attribute__((kernel)) root(uint32_t x, uint32_t y) { 46bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma // Convert x and y to floating point coordinates with center as origin 4750b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma const float2 inCoord = {(float)x, (float)y}; 4850b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma const float2 coord = mad(inCoord, inv_dimensions, neg_center); 4950b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma const float2 scaledCoord = axis_scale * coord; 5050b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma const float dist2 = scaledCoord.x*scaledCoord.x + scaledCoord.y*scaledCoord.y; 5150b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma const float inv_dist = rsqrt(dist2); 5250b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma const float radian = M_PI_2 - atan((alpha * sqrt(radius2 - dist2)) * inv_dist); 5350b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma const float scalar = radian * factor * inv_dist; 5450b1ba0083115c4fb578f13e0b94c6d80b5b1841Rajeev Sharma const float2 new_coord = mad(coord, scalar, center); 55bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma const float4 fout = rsSample(in_alloc, sampler, new_coord); 56d3d6570df4f39af697ba090fa8069aef6acfbcf4Stephen Hines return rsPackColorTo8888(fout); 57bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma} 58bb2c9476363d53f8a2888e263c171b588e21eeabRajeev Sharma 59