| /* |
| * Copyright (C) 2013 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. |
| */ |
| |
| #include "ip.rsh" |
| |
| |
| int height; |
| int width; |
| static int radius; |
| |
| rs_allocation InPixel; |
| rs_allocation ScratchPixel1; |
| rs_allocation ScratchPixel2; |
| |
| const int MAX_RADIUS = 25; |
| |
| // Store our coefficients here |
| static float gaussian[MAX_RADIUS * 2 + 1]; |
| |
| void setRadius(int rad) { |
| radius = rad; |
| // Compute gaussian weights for the blur |
| // e is the euler's number |
| float e = 2.718281828459045f; |
| float pi = 3.1415926535897932f; |
| // g(x) = ( 1 / sqrt( 2 * pi ) * sigma) * e ^ ( -x^2 / 2 * sigma^2 ) |
| // x is of the form [-radius .. 0 .. radius] |
| // and sigma varies with radius. |
| // Based on some experimental radius values and sigma's |
| // we approximately fit sigma = f(radius) as |
| // sigma = radius * 0.4 + 0.6 |
| // The larger the radius gets, the more our gaussian blur |
| // will resemble a box blur since with large sigma |
| // the gaussian curve begins to lose its shape |
| float sigma = 0.4f * (float)radius + 0.6f; |
| |
| // Now compute the coefficints |
| // We will store some redundant values to save some math during |
| // the blur calculations |
| // precompute some values |
| float coeff1 = 1.0f / (sqrt( 2.0f * pi ) * sigma); |
| float coeff2 = - 1.0f / (2.0f * sigma * sigma); |
| |
| float normalizeFactor = 0.0f; |
| float floatR = 0.0f; |
| for (int r = -radius; r <= radius; r ++) { |
| floatR = (float)r; |
| gaussian[r + radius] = coeff1 * pow(e, floatR * floatR * coeff2); |
| normalizeFactor += gaussian[r + radius]; |
| } |
| |
| //Now we need to normalize the weights because all our coefficients need to add up to one |
| normalizeFactor = 1.0f / normalizeFactor; |
| for (int r = -radius; r <= radius; r ++) { |
| floatR = (float)r; |
| gaussian[r + radius] *= normalizeFactor; |
| } |
| } |
| |
| float4 __attribute__((kernel)) copyIn(uchar4 in) { |
| return convert_float4(in); |
| } |
| |
| uchar4 __attribute__((kernel)) vert(uint32_t x, uint32_t y) { |
| float3 blurredPixel = 0; |
| int gi = 0; |
| uchar4 out; |
| if ((y > radius) && (y < (height - radius))) { |
| for (int r = -radius; r <= radius; r ++) { |
| float4 i = rsGetElementAt_float4(ScratchPixel2, x, y + r); |
| blurredPixel += i.xyz * gaussian[gi++]; |
| } |
| } else { |
| for (int r = -radius; r <= radius; r ++) { |
| int validH = rsClamp((int)y + r, (int)0, (int)(height - 1)); |
| float4 i = rsGetElementAt_float4(ScratchPixel2, x, validH); |
| blurredPixel += i.xyz * gaussian[gi++]; |
| } |
| } |
| |
| out.xyz = convert_uchar3(clamp(blurredPixel, 0.f, 255.f)); |
| out.w = 0xff; |
| return out; |
| } |
| |
| float4 __attribute__((kernel)) horz(uint32_t x, uint32_t y) { |
| float4 blurredPixel = 0; |
| int gi = 0; |
| if ((x > radius) && (x < (width - radius))) { |
| for (int r = -radius; r <= radius; r ++) { |
| float4 i = rsGetElementAt_float4(ScratchPixel1, x + r, y); |
| blurredPixel += i * gaussian[gi++]; |
| } |
| } else { |
| for (int r = -radius; r <= radius; r ++) { |
| // Stepping left and right away from the pixel |
| int validX = rsClamp((int)x + r, (int)0, (int)(width - 1)); |
| float4 i = rsGetElementAt_float4(ScratchPixel1, validX, y); |
| blurredPixel += i * gaussian[gi++]; |
| } |
| } |
| |
| return blurredPixel; |
| } |
| |