1 /* 2 * Copyright (C) 2012 The Android Open Source Project 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 static float2 neg_center, axis_scale, inv_dimensions; 18 static float sloped_neg_range, sloped_inv_max_dist, shade, opp_shade; 19 20 void init_vignette(uint32_t dim_x, uint32_t dim_y, float center_x, float center_y, 21 float desired_scale, float desired_shade, float desired_slope) { 22 23 neg_center.x = -center_x; 24 neg_center.y = -center_y; 25 inv_dimensions.x = 1.f / (float)dim_x; 26 inv_dimensions.y = 1.f / (float)dim_y; 27 28 axis_scale = (float2)1.f; 29 if (dim_x > dim_y) 30 axis_scale.y = (float)dim_y / (float)dim_x; 31 else 32 axis_scale.x = (float)dim_x / (float)dim_y; 33 34 const float max_dist = 0.5f * length(axis_scale); 35 sloped_inv_max_dist = desired_slope * 1.f/max_dist; 36 37 // Range needs to be between 1.3 to 0.6. When scale is zero then range is 38 // 1.3 which means no vignette at all because the luminousity difference is 39 // less than 1/256. Expect input scale to be between 0.0 and 1.0. 40 const float neg_range = 0.7f*sqrt(desired_scale) - 1.3f; 41 sloped_neg_range = exp(neg_range * desired_slope); 42 43 shade = desired_shade; 44 opp_shade = 1.f - desired_shade; 45 } 46 47 uchar4 __attribute__((kernel)) root(uchar4 in, uint32_t x, uint32_t y) { 48 // Convert x and y to floating point coordinates with center as origin 49 const float4 fin = convert_float4(in); 50 const float2 inCoord = {(float)x, (float)y}; 51 const float2 coord = mad(inCoord, inv_dimensions, neg_center); 52 const float sloped_dist_ratio = fast_length(axis_scale * coord) * sloped_inv_max_dist; 53 const float lumen = opp_shade + shade * half_recip(1.f + sloped_neg_range * native_exp(sloped_dist_ratio)); 54 float4 fout; 55 fout.rgb = fin.rgb * lumen; 56 fout.w = fin.w; 57 return convert_uchar4(fout); 58 } 59 60
