mutter/gles/cogl-fixed-fragment-shader.glsl

/*** cogl_fixed_fragment_shader_start ***/

/* There is no default precision for floats in fragment shaders in
   GLES 2 so we need to define one */
precision mediump float;

/* Inputs from the vertex shader */
varying vec4       frag_color;
varying vec2       tex_coord;
varying float      fog_amount;

/* Texturing options */
uniform sampler2D  texture_unit;

/* Fogging options */
uniform vec4       fog_color;

/* Alpha test options */
uniform float      alpha_test_ref;

void
main (void)
{
  /*** cogl_fixed_fragment_shader_texture_alpha_only ***/

  /* If the texture only has an alpha channel (eg, with the textures
     from the pango renderer) then the RGB components will be
     black. We want to use the RGB from the current color in that
     case */
  gl_FragColor = frag_color;
  gl_FragColor.a *= texture2D (texture_unit, tex_coord).a;

  /*** cogl_fixed_fragment_shader_texture ***/

  /* This pointless extra variable is needed to work around an
     apparent bug in the PowerVR drivers. Without it the alpha
     blending seems to stop working */
  vec4 frag_color_copy = frag_color;
  gl_FragColor = frag_color_copy * texture2D (texture_unit, tex_coord);

  /*** cogl_fixed_fragment_shader_solid_color ***/
  gl_FragColor = frag_color;

  /*** cogl_fixed_fragment_shader_fog ***/

  /* Mix the calculated color with the fog color */
  gl_FragColor.rgb = mix (fog_color.rgb, gl_FragColor.rgb, fog_amount);

  /* Alpha testing */

  /*** cogl_fixed_fragment_shader_alpha_never ***/
  discard;
  /*** cogl_fixed_fragment_shader_alpha_less ***/
  if (gl_FragColor.a >= alpha_test_ref)
    discard;
  /*** cogl_fixed_fragment_shader_alpha_equal ***/
  if (gl_FragColor.a != alpha_test_ref)
    discard;
  /*** cogl_fixed_fragment_shader_alpha_lequal ***/
  if (gl_FragColor.a > alpha_test_ref)
    discard;
  /*** cogl_fixed_fragment_shader_alpha_greater ***/
  if (gl_FragColor.a <= alpha_test_ref)
    discard;
  /*** cogl_fixed_fragment_shader_alpha_notequal ***/
  if (gl_FragColor.a == alpha_test_ref)
    discard;
  /*** cogl_fixed_fragment_shader_alpha_gequal ***/
  if (gl_FragColor.a < alpha_test_ref)
    discard;

  /*** cogl_fixed_fragment_shader_end ***/
}