git.sesse.net Git - nageru/blob - derivatives.frag

   1 #version 450 core
   2
   3 in vec2 tc;
   4 out vec2 derivatives;
   5
   6 uniform sampler2D tex;
   7 uniform vec2 inv_image_size;
   8
   9 void main()
  10 {
  11         float x_m2 = texture(tex, vec2(tc.x - 2.0 * inv_image_size.x), tc.y).x;
  12         float x_m1 = texture(tex, vec2(tc.x -       inv_image_size.x), tc.y).x;
  13         float x_p1 = texture(tex, vec2(tc.x +       inv_image_size.x), tc.y).x;
  14         float x_p2 = texture(tex, vec2(tc.x + 2.0 * inv_image_size.x), tc.y).x;
  15
  16         float y_m2 = texture(tex, vec2(tc.x, tc.y - 2.0 * inv_image_size.y)).x;
  17         float y_m1 = texture(tex, vec2(tc.x, tc.y -       inv_image_size.y)).x;
  18         float y_p1 = texture(tex, vec2(tc.x, tc.y +       inv_image_size.y)).x;
  19         float y_p2 = texture(tex, vec2(tc.x, tc.y + 2.0 * inv_image_size.y)).x;
  20
  21         derivatives.x = (x_p1 - x_m1) * (2.0/3.0) + (x_m2 - x_p2) * (1.0/12.0);
  22         derivatives.y = (y_p1 - y_m1) * (2.0/3.0) + (y_m2 - y_p2) * (1.0/12.0);
  23 }