1/* This Source Code Form is subject to the terms of the Mozilla Public 2 * License, v. 2.0. If a copy of the MPL was not distributed with this 3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ 4 5flat varying HIGHP_FS_ADDRESS int v_gradient_address; 6 7#if defined(PLATFORM_ANDROID) && !defined(SWGL) 8// Work around Adreno 3xx driver bug. See the v_perspective comment in 9// brush_image or bugs 1630356 and for details. 10flat varying vec2 v_gradient_repeat_vec; 11#define v_gradient_repeat v_gradient_repeat_vec.x 12#else 13// Repetition along the gradient stops. 14flat varying float v_gradient_repeat; 15#endif 16 17#ifdef WR_FRAGMENT_SHADER 18 19#ifdef WR_FEATURE_DITHERING 20vec4 dither(vec4 color) { 21 const int matrix_mask = 7; 22 23 ivec2 pos = ivec2(gl_FragCoord.xy) & ivec2(matrix_mask); 24 float noise_normalized = (texelFetch(sDither, pos, 0).r * 255.0 + 0.5) / 64.0; 25 float noise = (noise_normalized - 0.5) / 256.0; // scale down to the unit length 26 27 return color + vec4(noise, noise, noise, 0); 28} 29#else 30vec4 dither(vec4 color) { 31 return color; 32} 33#endif //WR_FEATURE_DITHERING 34 35#define GRADIENT_ENTRIES 128.0 36 37float clamp_gradient_entry(float offset) { 38 // Calculate the color entry index to use for this offset: 39 // offsets < 0 use the first color entry, 0 40 // offsets from [0, 1) use the color entries in the range of [1, N-1) 41 // offsets >= 1 use the last color entry, N-1 42 // so transform the range [0, 1) -> [1, N-1) 43 44 // TODO(gw): In the future we might consider making the size of the 45 // LUT vary based on number / distribution of stops in the gradient. 46 // Ensure we don't fetch outside the valid range of the LUT. 47 return clamp(1.0 + offset * GRADIENT_ENTRIES, 0.0, 1.0 + GRADIENT_ENTRIES); 48} 49 50vec4 sample_gradient(float offset) { 51 // Modulo the offset if the gradient repeats. 52 offset -= floor(offset) * v_gradient_repeat; 53 54 // Calculate the texel to index into the gradient color entries: 55 // floor(x) is the gradient color entry index 56 // fract(x) is the linear filtering factor between start and end 57 float x = clamp_gradient_entry(offset); 58 float entry_index = floor(x); 59 float entry_fract = x - entry_index; 60 61 // Fetch the start and end color. There is a [start, end] color per entry. 62 vec4 texels[2] = fetch_from_gpu_cache_2(v_gradient_address + 2 * int(entry_index)); 63 64 // Finally interpolate and apply dithering 65 return dither(texels[0] + texels[1] * entry_fract); 66} 67 68#endif //WR_FRAGMENT_SHADER 69