varying vec2 uv;
uniform sampler2D texture;
uniform float level;
const vec3 gray = vec3(0.30, 0.59, 0.11);

void main() {
	vec4 color = texture2D(texture, uv);
	gl_FragColor.rgb = mix(vec3(dot(gray, color.rgb * gl_Color.rgb)), color.rgb * gl_Color.rgb, level);
	gl_FragColor.a = color.a * gl_Color.a;
}