| /* |
| * Copyright (C) 2012 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| static float2 neg_center, axis_scale, inv_dimensions; |
| static float sloped_neg_range, sloped_inv_max_dist, shade, opp_shade; |
| |
| void init_vignette(uint32_t dim_x, uint32_t dim_y, float center_x, float center_y, |
| float desired_scale, float desired_shade, float desired_slope) { |
| |
| neg_center.x = -center_x; |
| neg_center.y = -center_y; |
| inv_dimensions.x = 1.f / (float)dim_x; |
| inv_dimensions.y = 1.f / (float)dim_y; |
| |
| axis_scale = (float2)1.f; |
| if (dim_x > dim_y) |
| axis_scale.y = (float)dim_y / (float)dim_x; |
| else |
| axis_scale.x = (float)dim_x / (float)dim_y; |
| |
| const float max_dist = 0.5f * length(axis_scale); |
| sloped_inv_max_dist = desired_slope * 1.f/max_dist; |
| |
| // Range needs to be between 1.3 to 0.6. When scale is zero then range is |
| // 1.3 which means no vignette at all because the luminousity difference is |
| // less than 1/256. Expect input scale to be between 0.0 and 1.0. |
| const float neg_range = 0.7f*sqrt(desired_scale) - 1.3f; |
| sloped_neg_range = exp(neg_range * desired_slope); |
| |
| shade = desired_shade; |
| opp_shade = 1.f - desired_shade; |
| } |
| |
| uchar4 __attribute__((kernel)) root(uchar4 in, uint32_t x, uint32_t y) { |
| // Convert x and y to floating point coordinates with center as origin |
| const float4 fin = convert_float4(in); |
| const float2 inCoord = {(float)x, (float)y}; |
| const float2 coord = mad(inCoord, inv_dimensions, neg_center); |
| const float sloped_dist_ratio = length(axis_scale * coord) * sloped_inv_max_dist; |
| const float lumen = opp_shade + shade / ( 1.0f + sloped_neg_range * exp(sloped_dist_ratio) ); |
| float4 fout; |
| fout.rgb = fin.rgb * lumen; |
| fout.w = fin.w; |
| return convert_uchar4(fout); |
| } |
| |