Hi,

I've got a weird “problem” happening when using Lambertian lighting in the lighting model VOP. When I eliminate my ambient light there's no change to the image even though there's a call to ambient() in the VEX code.

H6.1.208 on WIN-XP

Any ideas why ambient() may not be returning a value?

TIA!


–Mark

Could you give us an idea of what the code looks like?
(or the VOP network, in a screencap if possible)?

Hi,

The code looks correct to me, but when adjusting or deleting the ambient light in my scene, there's no change to the image. I also checked my light masks, they're set correctly. The code is being gen'd by the VEX builder, here's the section in question:


<SNIP>

if (0)
color12 = hsvtorgb(colormix(rgbtohsv(color10),
rgbtohsv(color11),
shaded_relief_amount, 1));
else
color12 = colormix(color10, color11, shaded_relief_amount, 1);

// Code produced by: lighting1
vector ii = 0 ? { 0.0, 0.0, 0.0 } : normalize(I);
vector nf = 0 ? { 0.0, 0.0, 0.0 } : normalize(N);

if (1) nf = frontface(nf, ii);

if (lmodel == “constant”)
{
color13 = color12;
}
else if (lmodel == “lambert”)
{
color13 = { 0, 0, 0 } * ambient()
+ color12 * diffuse(nf);
}
else if (lmodel == “headlight”)
{
color13 = color12*clamp(dot(nf, -ii), 0, 1);
}
else if (lmodel == “oren”)
{
color13 = { 0, 0, 0 } * ambient()
+ color12 * diffuse(nf, -ii, 0.05);
}
else if (lmodel == “phong”)
{
color13 = { 0, 0, 0 } * ambient()
+ color12 * diffuse(nf)
+ { 0, 0, 0 } * phong(nf, -ii, 1.0/0.05);
}
else if (lmodel == “blinn”)
{
color13 = { 0, 0, 0 } * ambient()
+ color12 * diffuse(nf)
+ { 0, 0, 0 } * blinn(nf, -ii, 0.05);
}
else if (lmodel == “anisotropic”)
{
color13 = { 0, 0, 0 } * ambient()
+ color12 * diffuse(nf)
+ { 0, 0, 0 } * anisotropic(nf, -ii, 0.05, 0.05);
}
else
{
color13 = { 0, 0, 0 } * ambient()
+ color12 * diffuse(nf)
+ { 0, 0, 0 } * specular(nf, -ii, 0.05);
}

// Code produced by: output1
Cf = color13;
}

Hi Mark,

The ambient() function is obviously being called. The problem is that you have “ambient tint” (or whatever it's called) in the lighting-model VOP set to {0,0,0}.

At least that's what this bit from your code-dump says:


else if (lmodel == “lambert”)
{
color13 = { 0, 0, 0 } * ambient()
+ color12 * diffuse(nf);
}


I'm talking about the {0,0,0} in the color13 = { 0, 0, 0 } * ambient() line

… and, of course, I'm also assuming that “lmodel” resolves to the string “lambert”.

Cheers!

Hi Mario!

Woops! It was staring at me the whole time! Doh! ops:

THANKS!!

Is it beer-thirty yet? :wink:


–Mark