Cross-hatching shader for Marmoset Toolbag 4

crosshatching.frag

// Based on http://research.microsoft.com/en-us/um/people/hoppe/hatching.pdf
// and https://github.com/spite/cross-hatching
#include "data/shader/mat/state.frag"

USE_TEXTURE2D(tHatch0);
USE_TEXTURE2D(tHatch1);
USE_TEXTURE2D(tHatch2);
USE_TEXTURE2D(tHatch3);
USE_TEXTURE2D(tHatch4);
USE_TEXTURE2D(tHatch5);

void CrossHatching( inout FragmentState s )
{
	vec2 vUv = s.vertexTexCoord.xy;
	float rim = saturate(dot(s.normal, s.vertexEye));
	rim *= rim;

	vec4 c = vec4(1.0, 1.0, 1.0, 1.0);
	float step = 1.0 / 6.0;
	if ( rim <= step ){
		c = mix( texture2D( tHatch5, vUv ), texture2D( tHatch4, vUv ), 6.0 * rim );
	}
	if ( rim > step && rim <= 2.0 * step ){
		c = mix( texture2D( tHatch4, vUv ), texture2D( tHatch3, vUv) , 6.0 * ( rim - step ) );
	}
	if ( rim > 2.0 * step && rim <= 3.0 * step ){
		c = mix( texture2D( tHatch3, vUv ), texture2D( tHatch2, vUv ), 6.0 * ( rim - 2.0 * step ) );
	}
	if ( rim > 3.0 * step && rim <= 4.0 * step ){
		c = mix( texture2D( tHatch2, vUv ), texture2D( tHatch1, vUv ), 6.0 * ( rim - 3.0 * step ) );
	}
	if ( rim > 4.0 * step && rim <= 5.0 * step ){
		c = mix( texture2D( tHatch1, vUv ), texture2D( tHatch0, vUv ), 6.0 * ( rim - 4.0 * step ) );
	}
	if ( rim > 5.0 * step ){
		c = mix( texture2D( tHatch0, vUv ), vec4(1.0, 1.0, 1.0, 1.0), 6.0 * ( rim - 5.0 * step ) );
	}

	s.emissiveLight = c.rgb;
}

#ifdef Emissive
	#undef Emissive
#endif
#define Emissive CrossHatching