float3 hatchWeight0 = float3(0.0, 0.0, 0.0); 
float3 hatchWeight1 = float3(0.0, 0.0, 0.0); 
// map tone to palette 
if(tone_level > t_5) { 
    hatchWeight0.x = 1.0; 
} else if(tone_level > t_4) { 
    hatchWeight0.x = 1.0 - (5.0 - tone_level); 
    hatchWeight0.y = 1.0 - hatchWeight0.x; 
} else if(tone_level > t_3) { 
    hatchWeight0.y = 1.0 - (4.0 - tone_level); 
    hatchWeight0.z = 1.0 - hatchWeight0.y; 
} else if(tone_level > t_2) { 
    hatchWeight0.z = 1.0 - (3.0 - tone_level); 
    hatchWeight1.x = 1.0 - hatchWeight0.z; 
} else if(tone_level > t_1) { 
    hatchWeight1.x = 1.0 - (2.0 - tone_level); 
    hatchWeight1.y = 1.0 - hatchWeight1.x; 
} else { 
    hatchWeight1.y = 1.0 - (1.0 - tone_level); 
    hatchWeight1.z = 1.0 - hatchWeight1.y; 
} 

//I just use the first 2 weights as pure white and the final 2 as the final texture 
//I did this because i only find hatching appealing in deeper shadows and i wanted the most fidelity in falloff areas 
//this also lets us use only 1 texture, with the alpha throretically saved for something else. 
float hatching = 1 * hatchWeight0.x; 
hatching += 1 * hatchWeight0.y;              
hatching += hatch_tex.x * hatchWeight0.z;               
hatching += hatch_tex.y * hatchWeight1.x; 
hatching += hatch_tex.z * hatchWeight1.y; 
hatching += hatch_tex.z * hatchWeight1.z; 
//multiply over the lighting 
//reverse the hatching, multiply by intensity, and then reverse back 
return 1-((1-hatching)*hatching_intensity);