volumetric lights

[melany]

Hello everyone,

..I have noticed that If I create a volumetric light with a vex lit fog shader and I place a common lights in my scene i just have a white rendered frame because my common light affects the volumetric one. Therefore I have to render my volumetric light as a single pass in order to be composited aftewards with my light pass. Is there a way in Houdini for rendering volumetric lights and common lights all in the same scene, as a single pass, without affecting each other?

thank you to all suggestions

[tallkien]

restrict the fog to cones?

[melany]

hello,

Thank u for your reply. I tried, but I does not work. I was looking for a parameter in the object view which could mask or link my athmosphere to my light, but I did not find anuthing about it. How can it be possible?

[AndrewVK]

You can add lightmask to litfog shader:

fog

litfog(

float density=0.05;

vector clr = 1;

...

...

...

string mask = "*";

)

{

...

...

...

...

illuminance(PP, {0, 0, 1}, M_PI, "lightmask", mask)

{

...

...

...

}

[melany]

hank u Andrew,

do I have to write a script or do I have to set some parameters which I cannot find?!!

I mean where is the illuminance parameter, and the vector one in my lit fog shader?

I apologies for my ignorance......I am still learning

[AndrewVK]

Fastest way to do this:

Load "VEX Lit Fog" shader.

Click right mouse button on it ---> Type Properties

Jump to VEX code tab

Add this line:

string Lightmask = "*";

after int n_octaves=3; but before ) character

Now find this line

illuminance(PP, {0, 0, 1}, M_PI)

and replace with

illuminance(PP, {0, 0, 1}, M_PI,"lightmask",Lightmask)

Push "Test Compile" button then "Accept"

Now You have Lightmask parameter.

Read drive:/HOUDINI 6.1/houdini/vex/html/shading.html#ctx_lightmask

for details.