1572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams/* 2572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams * Copyright (C) 2012 The Android Open Source Project 3572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams * 4572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams * Licensed under the Apache License, Version 2.0 (the "License"); 5572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams * you may not use this file except in compliance with the License. 6572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams * You may obtain a copy of the License at 7572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams * 8572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams * http://www.apache.org/licenses/LICENSE-2.0 9572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams * 10572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams * Unless required by applicable law or agreed to in writing, software 11572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams * distributed under the License is distributed on an "AS IS" BASIS, 12572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams * See the License for the specific language governing permissions and 14572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams * limitations under the License. 15572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams */ 16572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams 17572a5031a5d8602db0bec0b253428a034bd4dd59Jason Samsrs_allocation in_alloc; 18572a5031a5d8602db0bec0b253428a034bd4dd59Jason Samsrs_sampler sampler; 19572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams 20572a5031a5d8602db0bec0b253428a034bd4dd59Jason Samsstatic float2 center, neg_center, inv_dimensions, axis_scale; 21572a5031a5d8602db0bec0b253428a034bd4dd59Jason Samsstatic float alpha, radius2, factor; 22572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams 23572a5031a5d8602db0bec0b253428a034bd4dd59Jason Samsvoid init_filter(uint32_t dim_x, uint32_t dim_y, float center_x, float center_y, float k) { 24572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams center.x = center_x; 25572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams center.y = center_y; 26572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams neg_center = -center; 27572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams inv_dimensions.x = 1.f / (float)dim_x; 28572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams inv_dimensions.y = 1.f / (float)dim_y; 29572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams alpha = k * 2.0f + 0.75f; 30572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams 31572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams axis_scale = (float2)1.f; 32572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams if (dim_x > dim_y) 33572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams axis_scale.y = (float)dim_y / (float)dim_x; 34572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams else 35572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams axis_scale.x = (float)dim_x / (float)dim_y; 36859c4817355fcb86ea3aa103d1d1c5fa12ce81faJason Sams 37572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams const float bound2 = 0.25f * (axis_scale.x*axis_scale.x + axis_scale.y*axis_scale.y); 38572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams const float bound = sqrt(bound2); 39572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams const float radius = 1.15f * bound; 40572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams radius2 = radius*radius; 41572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams const float max_radian = M_PI_2 - atan(alpha / bound * sqrt(radius2 - bound2)); 42572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams factor = bound / max_radian; 43572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams} 44572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams 45572a5031a5d8602db0bec0b253428a034bd4dd59Jason Samsuchar4 __attribute__((kernel)) root(uint32_t x, uint32_t y) { 46572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams // Convert x and y to floating point coordinates with center as origin 47572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams const float2 inCoord = {(float)x, (float)y}; 48572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams const float2 coord = mad(inCoord, inv_dimensions, neg_center); 49572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams const float2 scaledCoord = axis_scale * coord; 50572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams const float dist2 = scaledCoord.x*scaledCoord.x + scaledCoord.y*scaledCoord.y; 51572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams const float inv_dist = rsqrt(dist2); 52572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams const float radian = M_PI_2 - atan((alpha * sqrt(radius2 - dist2)) * inv_dist); 53572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams const float scalar = radian * factor * inv_dist; 54572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams const float2 new_coord = mad(coord, scalar, center); 55572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams const float4 fout = rsSample(in_alloc, sampler, new_coord); 56572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams return rsPackColorTo8888(fout); 57572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams} 58572a5031a5d8602db0bec0b253428a034bd4dd59Jason Sams 59