#ifdef GL_ES
#ifdef GL_FRAGMENT_PRECISION_HIGH
precision highp float;
#else
precision mediump float;
#endif
#endif
uniform sampler2D tex;
varying vec2 tex_c;
void main()
{
   float inten = dot(texture2D(tex,tex_c.xy).abg,vec3(.3, .59, .11));
   gl_FragColor = vec4(inten, inten, inten, texture2D(tex,tex_c.xy).r);
}