/system/shaders/stretch.glsl

http://github.com/xbmc/xbmc · GLSL · 39 lines · 13 code · 4 blank · 22 comment · 0 complexity · 0101af42ce7633db5753c2543444c741 MD5 · raw file

  1. /*
  2. * Copyright (C) 2010-2013 Team XBMC
  3. * http://xbmc.org
  4. *
  5. * This Program is free software; you can redistribute it and/or modify
  6. * it under the terms of the GNU General Public License as published by
  7. * the Free Software Foundation; either version 2, or (at your option)
  8. * any later version.
  9. *
  10. * This Program is distributed in the hope that it will be useful,
  11. * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12. * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13. * GNU General Public License for more details.
  14. *
  15. * You should have received a copy of the GNU General Public License
  16. * along with XBMC; see the file COPYING. If not, see
  17. * <http://www.gnu.org/licenses/>.
  18. *
  19. */
  20. uniform sampler2D img;
  21. uniform float m_stretch;
  22. varying vec2 cord;
  23. vec2 stretch(vec2 pos)
  24. {
  25. // our transform should map [0..1] to itself, with f(0) = 0, f(1) = 1, f(0.5) = 0.5, and f'(0.5) = b.
  26. // a simple curve to do this is g(x) = b(x-0.5) + (1-b)2^(n-1)(x-0.5)^n + 0.5
  27. // where the power preserves sign. n = 2 is the simplest non-linear case (required when b != 1)
  28. float x = pos.x - 0.5;
  29. return vec2(mix(x * abs(x) * 2.0, x, m_stretch) + 0.5, pos.y);
  30. }
  31. void main()
  32. {
  33. gl_FragColor.rgb = texture2D(img, stretch(cord)).rgb;
  34. gl_FragColor.a = gl_Color.a;
  35. }