translucency

[MENOZ]

hello.

i'm trying to create a translucency effect in VOP.

i tried the translucency shader that comes with houdini, but it doesn't work.

the maple leaf shader works

i looked in the network and the way the translucency effect is built seems to be the same.

i don't understand why one works and the other doesn't.

anyway, i'm not shure about using the frontFace vop, instead of the isFrontFace, because this should give me a varying translucency effect, is this correct?

if i use isFrontFace to control the bias of the mixLambertColor it works. but how can i blur the shadow of the objects behind?.

thank you!

[MENOZ]

hello.

i'm trying to create a translucency effect in VOP.

i tried the translucency shader that comes with houdini, but it doesn't work.

the maple leaf shader works

i looked in the network and the way the translucency effect is built seems to be the same.

i don't understand why one works and the other doesn't.

anyway, i'm not shure about using the frontFace vop, instead of the isFrontFace, because this should give me a varying translucency effect, is this correct?

if i use isFrontFace to control the bias of the mixLambertColor it works. but how can i blur the shadow of the objects behind?.

thank you!

is there a node that can blur or filter a color? in VOP.

[symek]

is there a node that can blur or filter a color? in VOP.

Definitely a job for point cloud... unless you don't want to multi-sample shadows.

EDIT: sorry, just reread previous post... doesn't blurry depth maps work for you?

Edited June 24, 2008 by SYmek

[MENOZ]

Definitely a job for point cloud... unless you don't want to multi-sample shadows.

EDIT: sorry, just reread previous post... doesn't blurry depth maps work for you?

yes, if i use blurred shadow it works, but i have blurred shadow on the other side too.

could you make me an example with point clouds please?

thanks!

[symek]

yes, if i use blurred shadow it works, but i have blurred shadow on the other side too.

could you make me an example with point clouds please?

thanks!

Hi MENOZ,

sorry for late answer. I hadn't time to play with it. This is just a quick example of what I meant. By no means this is accurate or correct. Some corrections in vectors are needed but I really had a moment...

This is translucency opacity test via standard shadow() call

This is translucency with surface color:

These are both:

Point cloud was generated in SOPs, because I'm lazy (BTW it need to carry point normals). Perhaps pcwrite() with pre-pass computation would be better way. There are also some artifacts and no eta for refraction. Corrections highly recommended!

cheers,

sy.

#include <math.h>
surface
milk_glass(vector trans = 0.5;
	   vector diff = 0.7;
	   string pcmap = "";
	   float maxdist = 1;
	   int maxpoints = 50;)

{

	vector pcP = 0;
	vector pcN = 0;
	vector tlight = 0;
	vector nN;

	vector cf, of;
	float af;

	vector pp = ptransform("space:object", P);
	vector Nf = frontface(normalize(N), normalize(I));
	int handle = pcopen(pcmap, "P", pp, maxdist, maxpoints);

	while(pcunshaded(handle, "tlight"))
	{
		pcimport(handle, "P", pcP);
		pcimport(handle, "N", pcN);
		pcN = ntransform("space:object", "space:camera", pcN);	
		nN = -frontface(normalize(pcN),I);
		pcP = ptransform("space:object", "space:camera", pcP);

		illuminance(pcP, nN, M_PI/2)
		{
		vector nL = normalize(L+(P-pcP));
		shadow(Cl);
		tlight  += Cl * dot(nL, nN);
		} 

		refractlight(cf, of, af, pcP, I, 0.005, max(trans));

		int success = pcexport(handle, "tlight", cf+clamp(tlight, {0,0,0},{1,1,1}));


	}


	tlight = pcfilter(handle, "tlight");

	Cf = tlight*trans + diffuse(Nf)*diff;
	Of = 1;



}

Edited June 30, 2008 by SYmek

[TheUsualAlex]

cool simon. I'll have to play with this.

[Jason]

cool simon. I'll have to play with this.

Very nice! :-D