texture framebuffer
float offset

effect
{
	vec2 offx = vec2(offset, 0.0);
	vec2 offy = vec2(0.0, offset);

	vec4 c0 = framebuffer(_in);
	vec4 c1 = framebuffer(_in - offy);
	vec4 c2 = framebuffer(_in + offy);
	vec4 c3 = framebuffer(_in - offx);
	vec4 c4 = framebuffer(_in + offx);

	_out = c0 * 0.2 + c1 * 0.2 + c2 * 0.2 + c3 * 0.2 + c4 * 0.2;
}