1 /* 2 * Copyright (C) 2022 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 package com.android.systemui.surfaceeffects.shaderutil 17 18 /** A common utility functions that are used for computing shaders. */ 19 class ShaderUtilLibrary { 20 // language=AGSL 21 companion object { 22 const val SHADER_LIB = 23 """ 24 float triangleNoise(vec2 n) { 25 n = fract(n * vec2(5.3987, 5.4421)); 26 n += dot(n.yx, n.xy + vec2(21.5351, 14.3137)); 27 float xy = n.x * n.y; 28 // compute in [0..2[ and remap to [-1.0..1.0[ 29 return fract(xy * 95.4307) + fract(xy * 75.04961) - 1.0; 30 } 31 32 const float PI = 3.1415926535897932384626; 33 34 float sparkles(vec2 uv, float t) { 35 float n = triangleNoise(uv); 36 float s = 0.0; 37 for (float i = 0; i < 4; i += 1) { 38 float l = i * 0.01; 39 float h = l + 0.1; 40 float o = smoothstep(n - l, h, n); 41 o *= abs(sin(PI * o * (t + 0.55 * i))); 42 s += o; 43 } 44 return s; 45 } 46 47 vec2 distort(vec2 p, float time, float distort_amount_radial, 48 float distort_amount_xy) { 49 float angle = atan(p.y, p.x); 50 return p + vec2(sin(angle * 8 + time * 0.003 + 1.641), 51 cos(angle * 5 + 2.14 + time * 0.00412)) * distort_amount_radial 52 + vec2(sin(p.x * 0.01 + time * 0.00215 + 0.8123), 53 cos(p.y * 0.01 + time * 0.005931)) * distort_amount_xy; 54 } 55 56 // Return range [-1, 1]. 57 vec3 hash(vec3 p) { 58 p = fract(p * vec3(.3456, .1234, .9876)); 59 p += dot(p, p.yxz + 43.21); 60 p = (p.xxy + p.yxx) * p.zyx; 61 return (fract(sin(p) * 4567.1234567) - .5) * 2.; 62 } 63 64 // Skew factors (non-uniform). 65 const float SKEW = 0.3333333; // 1/3 66 const float UNSKEW = 0.1666667; // 1/6 67 68 // Return range roughly [-1,1]. 69 // It's because the hash function (that returns a random gradient vector) returns 70 // different magnitude of vectors. Noise doesn't have to be in the precise range thus 71 // skipped normalize. 72 float simplex3d(vec3 p) { 73 // Skew the input coordinate, so that we get squashed cubical grid 74 vec3 s = floor(p + (p.x + p.y + p.z) * SKEW); 75 76 // Unskew back 77 vec3 u = s - (s.x + s.y + s.z) * UNSKEW; 78 79 // Unskewed coordinate that is relative to p, to compute the noise contribution 80 // based on the distance. 81 vec3 c0 = p - u; 82 83 // We have six simplices (in this case tetrahedron, since we are in 3D) that we 84 // could possibly in. 85 // Here, we are finding the correct tetrahedron (simplex shape), and traverse its 86 // four vertices (c0..3) when computing noise contribution. 87 // The way we find them is by comparing c0's x,y,z values. 88 // For example in 2D, we can find the triangle (simplex shape in 2D) that we are in 89 // by comparing x and y values. i.e. x>y lower, x<y, upper triangle. 90 // Same applies in 3D. 91 // 92 // Below indicates the offsets (or offset directions) when c0=(x0,y0,z0) 93 // x0>y0>z0: (1,0,0), (1,1,0), (1,1,1) 94 // x0>z0>y0: (1,0,0), (1,0,1), (1,1,1) 95 // z0>x0>y0: (0,0,1), (1,0,1), (1,1,1) 96 // z0>y0>x0: (0,0,1), (0,1,1), (1,1,1) 97 // y0>z0>x0: (0,1,0), (0,1,1), (1,1,1) 98 // y0>x0>z0: (0,1,0), (1,1,0), (1,1,1) 99 // 100 // The rule is: 101 // * For offset1, set 1 at the max component, otherwise 0. 102 // * For offset2, set 0 at the min component, otherwise 1. 103 // * For offset3, set 1 for all. 104 // 105 // Encode x0-y0, y0-z0, z0-x0 in a vec3 106 vec3 en = c0 - c0.yzx; 107 // Each represents whether x0>y0, y0>z0, z0>x0 108 en = step(vec3(0.), en); 109 // en.zxy encodes z0>x0, x0>y0, y0>x0 110 vec3 offset1 = en * (1. - en.zxy); // find max 111 vec3 offset2 = 1. - en.zxy * (1. - en); // 1-(find min) 112 vec3 offset3 = vec3(1.); 113 114 vec3 c1 = c0 - offset1 + UNSKEW; 115 vec3 c2 = c0 - offset2 + UNSKEW * 2.; 116 vec3 c3 = c0 - offset3 + UNSKEW * 3.; 117 118 // Kernel summation: dot(max(0, r^2-d^2))^4, noise contribution) 119 // 120 // First compute d^2, squared distance to the point. 121 vec4 w; // w = max(0, r^2 - d^2)) 122 w.x = dot(c0, c0); 123 w.y = dot(c1, c1); 124 w.z = dot(c2, c2); 125 w.w = dot(c3, c3); 126 127 // Noise contribution should decay to zero before they cross the simplex boundary. 128 // Usually r^2 is 0.5 or 0.6; 129 // 0.5 ensures continuity but 0.6 increases the visual quality for the application 130 // where discontinuity isn't noticeable. 131 w = max(0.6 - w, 0.); 132 133 // Noise contribution from each point. 134 vec4 nc; 135 nc.x = dot(hash(s), c0); 136 nc.y = dot(hash(s + offset1), c1); 137 nc.z = dot(hash(s + offset2), c2); 138 nc.w = dot(hash(s + offset3), c3); 139 140 nc *= w*w*w*w; 141 142 // Add all the noise contributions. 143 // Should multiply by the possible max contribution to adjust the range in [-1,1]. 144 return dot(vec4(32.), nc); 145 } 146 """ 147 } 148 } 149