| |
| /* |
| ** Copyright (c) 2012 The Khronos Group Inc. |
| ** |
| ** Permission is hereby granted, free of charge, to any person obtaining a |
| ** copy of this software and/or associated documentation files (the |
| ** "Materials"), to deal in the Materials without restriction, including |
| ** without limitation the rights to use, copy, modify, merge, publish, |
| ** distribute, sublicense, and/or sell copies of the Materials, and to |
| ** permit persons to whom the Materials are furnished to do so, subject to |
| ** the following conditions: |
| ** |
| ** The above copyright notice and this permission notice shall be included |
| ** in all copies or substantial portions of the Materials. |
| ** |
| ** THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
| ** EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| ** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
| ** IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY |
| ** CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, |
| ** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE |
| ** MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS. |
| */ |
| |
| |
| #ifdef GL_ES |
| precision mediump float; |
| #endif |
| varying vec4 color; |
| |
| void main (void) |
| { |
| vec2 x = 31.0 * color.rg + 1.0; |
| vec2 y = vec2(0.0); |
| vec2 z; // x-1 / x+1 |
| int n = 50; |
| |
| // ln(x) = 2[x-1 + 1 (x-1)^3 + 1 (x-1)^5 + ...] for x > 0 |
| // [x+1 3 (x+1) 5 (x+1) ] |
| z = (x - 1.0) / (x + 1.0); |
| vec2 p = z; |
| for(int i = 1; i <= 101; i += 2) |
| { |
| y += p / float(i); |
| p *= z * z; |
| } |
| y *= 2.0; |
| |
| gl_FragColor = vec4(y / 3.466, 0.0, 1.0); |
| } |