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 9attribute vec4 gtf_Vertex; 10attribute vec4 gtf_Color; 11uniform mat4 gtf_ModelViewProjectionMatrix; 12varying vec4 color; 13 14void main (void) 15{ 16 const float M_PI = 3.14159265358979323846; 17 vec3 x = 2.0 * (gtf_Color.ggg - 0.5); 18 vec3 y = 2.0 * (gtf_Color.bbb - 0.5); 19 const float epsilon = 1.0e-4; 20 color = vec4(0.0, 0.0, 0.0, 1.0); 21 22 // Avoid evaluating atan(0, x) for x < epsilon because it's implementation-dependent 23 if(x[0] > epsilon || abs(y[0]) > epsilon) 24 { 25 color[0] = atan(y[0], x[0]) / (2.0 * M_PI) + 0.5; 26 } 27 28 if(x[1] > epsilon || abs(y[1]) > epsilon) 29 { 30 color[1] = atan(y[1], x[1]) / (2.0 * M_PI) + 0.5; 31 } 32 33 if(x[2] > epsilon || abs(y[2]) > epsilon) 34 { 35 color[2] = atan(y[2], x[2]) / (2.0 * M_PI) + 0.5; 36 } 37 38 gl_Position = gtf_ModelViewProjectionMatrix * gtf_Vertex; 39} 40