1 2/* 3Copyright (c) 2019 The Khronos Group Inc. 4Use of this source code is governed by an MIT-style license that can be 5found in the LICENSE.txt file. 6*/ 7 8 9#ifdef GL_ES 10precision mediump float; 11#endif 12varying vec4 color; 13 14void main (void) 15{ 16 const float M_PI = 3.14159265358979323846; 17 vec2 c = 4.0 * 2.0 * (color.rg - 0.5); 18 vec2 atan_c = vec2(0.0); 19 vec2 scale = vec2(1.0); 20 vec2 sign = vec2(1.0); 21 vec4 result = vec4(0.0, 0.0, 0.0, 1.0); 22 23 if(c[0] < 0.0) 24 { 25 sign[0] = -1.0; 26 c[0] *= -1.0; 27 } 28 29 if(c[0] <= 1.0) 30 { 31 // Taylors series expansion for atan 32 atan_c[0] += scale[0] * pow(c[0], float(1)) / float(1); 33 scale[0] *= -1.0; 34 atan_c[0] += scale[0] * pow(c[0], float(3)) / float(3); 35 scale[0] *= -1.0; 36 atan_c[0] += scale[0] * pow(c[0], float(5)) / float(5); 37 scale[0] *= -1.0; 38 atan_c[0] += scale[0] * pow(c[0], float(7)) / float(7); 39 scale[0] *= -1.0; 40 atan_c[0] += scale[0] * pow(c[0], float(9)) / float(9); 41 scale[0] *= -1.0; 42 atan_c[0] += scale[0] * pow(c[0], float(11)) / float(11); 43 scale[0] *= -1.0; 44 45 result[0] = sign[0] * atan_c[0] / M_PI + 0.5; 46 } 47 else 48 { 49 c[0] = 1.0 / c[0]; 50 51 // Taylors series expansion for atan 52 atan_c[0] += scale[0] * pow(c[0], float(1)) / float(1); 53 scale[0] *= -1.0; 54 atan_c[0] += scale[0] * pow(c[0], float(3)) / float(3); 55 scale[0] *= -1.0; 56 atan_c[0] += scale[0] * pow(c[0], float(5)) / float(5); 57 scale[0] *= -1.0; 58 atan_c[0] += scale[0] * pow(c[0], float(7)) / float(7); 59 scale[0] *= -1.0; 60 atan_c[0] += scale[0] * pow(c[0], float(9)) / float(9); 61 scale[0] *= -1.0; 62 atan_c[0] += scale[0] * pow(c[0], float(11)) / float(11); 63 scale[0] *= -1.0; 64 65 result[0] = sign[0] * (M_PI / 2.0 - atan_c[0]) / M_PI + 0.5; 66 } 67 68 69 if(c[1] < 0.0) 70 { 71 sign[1] = -1.0; 72 c[1] *= -1.0; 73 } 74 75 if(c[1] <= 1.0) 76 { 77 // Taylors series expansion for atan 78 atan_c[1] += scale[1] * pow(c[1], float(1)) / float(1); 79 scale[1] *= -1.0; 80 atan_c[1] += scale[1] * pow(c[1], float(3)) / float(3); 81 scale[1] *= -1.0; 82 atan_c[1] += scale[1] * pow(c[1], float(5)) / float(5); 83 scale[1] *= -1.0; 84 atan_c[1] += scale[1] * pow(c[1], float(7)) / float(7); 85 scale[1] *= -1.0; 86 atan_c[1] += scale[1] * pow(c[1], float(9)) / float(9); 87 scale[1] *= -1.0; 88 atan_c[1] += scale[1] * pow(c[1], float(11)) / float(11); 89 scale[1] *= -1.0; 90 91 result[1] = sign[1] * atan_c[1] / M_PI + 0.5; 92 } 93 else 94 { 95 c[1] = 1.0 / c[1]; 96 97 // Taylors series expansion for atan 98 atan_c[1] += scale[1] * pow(c[1], float(1)) / float(1); 99 scale[1] *= -1.0; 100 atan_c[1] += scale[1] * pow(c[1], float(3)) / float(3); 101 scale[1] *= -1.0; 102 atan_c[1] += scale[1] * pow(c[1], float(5)) / float(5); 103 scale[1] *= -1.0; 104 atan_c[1] += scale[1] * pow(c[1], float(7)) / float(7); 105 scale[1] *= -1.0; 106 atan_c[1] += scale[1] * pow(c[1], float(9)) / float(9); 107 scale[1] *= -1.0; 108 atan_c[1] += scale[1] * pow(c[1], float(11)) / float(11); 109 scale[1] *= -1.0; 110 111 result[1] = sign[1] * (M_PI / 2.0 - atan_c[1]) / M_PI + 0.5; 112 } 113 114 gl_FragColor = result; 115} 116