How to use Animated Gobos in Houdini

1. Launch Greyscalegorilla Studio and download any Animated Gobo you would like to use.

2. In Houdini go to Object Context and create a Light (hit Tab key and type light then select the RS Light). In this guide we will be using Redshift however the workflow is same for all renderers.

3. After you create the RS Light go to it's Attributes > Light tab and check "Use Texture" under Color section, this will enable the Texture tab where you can load the Animated Gobo texture sequence.

4. Switch to Studio click and drag the Animated Gobo thumbnail into the Light > Attributes > Texture path box. (Or you can click the "Copy" icon on Animated Gobo thumbnail and then paste into the Texture path box.)

5. When you assign the Animated Gobo you will see the file name of the first frame in the Filename box which ends with 000. (please check the image below)

• Houdini doesn't play the sequence by default, to play whole animation sequence once you need to replace that three digits of zero to $F3

  i.e. GSG_GC002_A003_Caustics01_000.jpg to GSG_GC002_A003_Caustics01_$F3.jpg

• if you want to offset the animation replace with `padzero(3,$F-10)`

  i.e. to GSG_GC002_A003_Caustics01_`padzero(3,$F-10)`.jpg

  (in this example -10 is the offset number, you can use negative or positive values)

• if you want to loop the gobo animation every "n" frames replace with `padzero(3,$F%180)`

  i.e. to GSG_GC002_A003_Caustics01_`padzero(3,$F%180)`.jpg

  (in this example it will loop every 180 frames)

6. After you make your changes to the Animated Gobo sequence you can render your scene and move the timeline to confirm it's working.