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| 1 |
| 2 /* |
| 3 ** Copyright (c) 2012 The Khronos Group Inc. |
| 4 ** |
| 5 ** Permission is hereby granted, free of charge, to any person obtaining a |
| 6 ** copy of this software and/or associated documentation files (the |
| 7 ** "Materials"), to deal in the Materials without restriction, including |
| 8 ** without limitation the rights to use, copy, modify, merge, publish, |
| 9 ** distribute, sublicense, and/or sell copies of the Materials, and to |
| 10 ** permit persons to whom the Materials are furnished to do so, subject to |
| 11 ** the following conditions: |
| 12 ** |
| 13 ** The above copyright notice and this permission notice shall be included |
| 14 ** in all copies or substantial portions of the Materials. |
| 15 ** |
| 16 ** THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
| 17 ** EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| 18 ** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
| 19 ** IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY |
| 20 ** CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, |
| 21 ** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE |
| 22 ** MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS. |
| 23 */ |
| 24 |
| 25 |
| 26 attribute vec4 gtf_Color; |
| 27 attribute vec4 gtf_Vertex; |
| 28 uniform mat4 gtf_ModelViewProjectionMatrix; |
| 29 varying vec4 color; |
| 30 const float ln2 = 0.69314718055994530941723212145818; |
| 31 |
| 32 |
| 33 |
| 34 void main (void) |
| 35 { |
| 36 vec3 x = 31.0 * gtf_Color.rgb + 1.0; |
| 37 vec3 y = vec3(0.0); |
| 38 vec3 z; // x-1 / x+1 |
| 39 int n = 50; |
| 40 |
| 41 // ln(x) = 2[x-1 + 1 (x-1)^3 + 1 (x-1)^5 + ...] for x > 0 |
| 42 // [x+1 3 (x+1) 5 (x+1) ] |
| 43 z = (x - 1.0) / (x + 1.0); |
| 44 vec3 p = z; |
| 45 for(int i = 1; i <= 101; i += 2) |
| 46 { |
| 47 y += p / float(i); |
| 48 p *= z * z; |
| 49 } |
| 50 y *= 2.0 / ln2; |
| 51 |
| 52 color = vec4(y / 5.0, 1.0); |
| 53 gl_Position = gtf_ModelViewProjectionMatrix * gtf_Vertex; |
| 54 } |
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