High Contrast Shader

Black and White Lines
Goal: Create a shader that generates white lines where a surface would normally gradate from light to dark. Be able to manipulate the width of the lines and the number of lines generated.

With Shader applied to a Maya model Black and White lines without smoothstep function With 20 lines and 3 lights

With 5 lines and 2 lights

Maya Scene

Adjusting Number of Lines

Varying Line Width

Shader Settings in Maya This set of sliders in Slim be used to effect the number of lines and the weight of the line.

Probelm Solving smoothstep
Black and White lines with the smoothstep function

Code For Smoothstep
for(i = 0; i < num; i = i+1)
    {
    grey02 += smoothstep(base01,base02,grey)
    * (1-smoothstep(base01,base02,grey));
    base01 += wt*2;
    base02 += wt*2;
    }

Lines are appearing grey. This is probably due to the gradients fom the edges of the smoothstep are overlapping each other. I need to add a variable to adjust the smoothness factor.

Shader with smoothstep on a Maya Model I increased the Kd value and used two lights.

Full Code

/*	high contrast shader:
	Where lights are forced to white and darks are forced to black.*/

surface
high_contrast(	float	Kd = 1,
						smoothness = .2,
						cutoff = 1,
						num = 1,
						wt = .5;
				string	texmap = "")	

{
/*color	surfcolor = texture(texmap,s,t);*/
color	surfcolor = 1;
normal	n = normalize(N);
normal	nf = faceforward(n, I);

color	c1 = diffuse(nf);

float	grey = (comp(c1,0)+comp(c1,1)+comp(c1,2))/3;
float	i, base01 = 0, base02 = wt, grey02 = 0;

Oi = Os;

/* 	make either black or white - force threshold to .5 so light
	greys become white
*/

/*This generates the lines with smoothstepping but with a lot of greyness
....I think because the smoothstep is overcoming the white.*/

/*for(i = 0; i < num; i = i+1) {
	grey02 += smoothstep(base01,base02,grey) *
				(1-smoothstep(base01,base02,grey));
	base01 += wt*2;
	base02 += wt*2;

}
*/

/*This creates lines without smoothstepping */
for(i = 0; i < num; i = i+1) {
	if(grey > base01 && grey < base02)
		grey02 = 1;
	else
		grey02 += 0;
	base01 += wt*2;
	base02 += wt*2;

}




Ci = Oi * Cs * surfcolor * grey02 * Kd;
}