CGTalk - Newbie question about Renderman

View Full Version : Newbie question about Renderman

lazzhar

11-30-2003, 07:58 PM

Hi,
I suppose there is no place where to ask about Renderman so I'm posting here.
I've created a simple objects in a scene then lit them with a Spot and Direction Light in Maya. Then attached a light Shader to th Spot in Slim. When trying to render I cannot see the effect of the Spot light, Just the objects are lit by the directional light wich doesnt have a Slim Shader (not shady) attached.
Because I'm learning how change RIB files and Shaders I've tryd to fix the problem by hand but noway.
So here is the RIB file and the light Shader:
http://lazzzhar.jeeran.com/untitled.0001.rib.txt
http://lazzzhar.jeeran.com/lazzharSpot.sl.txt

Hope to find a help.

fxjeane

11-30-2003, 11:00 PM

Hi there Lazzhar!
I looked at your scene file and I didnt see an "intensity" value for your spotlight. which means the shader is using the default (probably 1).

I think the problem might be that the shader is using a square or cubic fallof, which means you will probably need to give it a value a lot higher than 1. You dont have this problem with the directional light because they have no falloff, so a value of 0.25 will have its effect.

Try incrementing the values by 10 (10,100,1000) and see if the light has any effect. Give the light a brigt distinctive color while testing so you know if its making a difference. The intensity of the light will have a lot to do with the scale and units of your scene.

I hope that works

Rudy

lazzhar

12-01-2003, 07:59 PM

Hi Rudy,
I tryed your idea in Slim but it seems that the fallof attribute of my spot light is set to none, however I increased the intensity till 1000 without any success.
I think the problem is that the light source in the RIB file is not taking the same position of the light in Maya. Not sure but just an idea.
But I'm wondering why i dont front this problem when I use the ready light shaders of RAT like ratSpot. It works fine but I dont want to use it I 'd like to learn how to build a light shader from the scratch.
Thanks Rudy for your feedback.

CGTalk Moderation

01-16-2006, 07:00 PM

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.