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