git.sesse.net Git - nageru/blob - futatabi/sor.vert

   1 #version 450 core
   2 #extension GL_ARB_shader_viewport_layer_array : require
   3
   4 layout(location=0) in vec2 position;
   5 out vec3 tc, tc_left, tc_down;
   6 out vec3 equation_tc_assuming_left, equation_tc_assuming_right;
   7 out float element_x_idx;
   8 out float element_sum_idx;
   9
  10 uniform sampler2DArray diff_flow_tex, diffusivity_tex;
  11 uniform usampler2DArray equation_red_tex;
  12
  13 void main()
  14 {
  15         // The result of glOrtho(0.0, 1.0, 0.0, 1.0, 0.0, 1.0) is:
  16         //
  17         //   2.000  0.000  0.000 -1.000
  18         //   0.000  2.000  0.000 -1.000
  19         //   0.000  0.000 -2.000 -1.000
  20         //   0.000  0.000  0.000  1.000
  21         gl_Position = vec4(2.0 * position.x - 1.0, 2.0 * position.y - 1.0, -1.0, 1.0);
  22         gl_Layer = gl_InstanceID;
  23
  24         tc = vec3(position, gl_InstanceID);
  25         tc_left = vec3(tc.x - 0.5f / textureSize(diffusivity_tex, 0).x, tc.y, gl_InstanceID);
  26         tc_down = vec3(tc.x, tc.y - 0.5f / textureSize(diffusivity_tex, 0).y, gl_InstanceID);
  27
  28         // The equation textures have half the horizontal width, so we need to adjust the texel centers.
  29         // It becomes extra tricky since the SOR texture might be of odd size, and then
  30         // the equation texture is not exactly half the size.
  31         vec2 element_idx = position * textureSize(diff_flow_tex, 0).xy - 0.5f;
  32         float equation_texel_number_assuming_left = element_idx.x / 2.0f;
  33         float equation_texel_number_assuming_right = (element_idx.x - 1.0f) / 2.0f;
  34         equation_tc_assuming_left.x = (equation_texel_number_assuming_left + 0.5f) / textureSize(equation_red_tex, 0).x;
  35         equation_tc_assuming_right.x = (equation_texel_number_assuming_right + 0.5f) / textureSize(equation_red_tex, 0).x;
  36         equation_tc_assuming_left.y = tc.y;
  37         equation_tc_assuming_right.y = tc.y;
  38         equation_tc_assuming_left.z = gl_InstanceID;
  39         equation_tc_assuming_right.z = gl_InstanceID;
  40
  41         element_x_idx = element_idx.x;
  42         element_sum_idx = element_idx.x + element_idx.y;
  43 }