1 files changed, 41 insertions, 0 deletions
diff --git a/system/shaders/GL/1.2/gl_stretch.glsl b/system/shaders/GL/1.2/gl_stretch.glsl
new file mode 100644
index 0000000..9cc3388
--- /dev/null
+++ b/system/shaders/GL/1.2/gl_stretch.glsl
@@ -0,0 +1,41 @@
+/*
+ *      Copyright (C) 2010-2013 Team XBMC
+ *      http://xbmc.org
+ *
+ *  This Program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2, or (at your option)
+ *  any later version.
+ *
+ *  This Program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with XBMC; see the file COPYING.  If not, see
+ *  <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#version 120
+
+uniform sampler2D img;
+uniform float  m_stretch;
+uniform float m_alpha;
+varying vec2  m_cord;
+
+vec2 stretch(vec2 pos)
+{
+  // 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.
+  // a simple curve to do this is g(x) = b(x-0.5) + (1-b)2^(n-1)(x-0.5)^n + 0.5
+  // where the power preserves sign. n = 2 is the simplest non-linear case (required when b != 1)
+  float x = pos.x - 0.5;
+  return vec2(mix(x * abs(x) * 2.0, x, m_stretch) + 0.5, pos.y);
+}
+
+void main()
+{
+  gl_FragColor.rgb = texture2D(img, stretch(m_cord)).rgb;
+  gl_FragColor.a = m_alpha;
+}