Shader to make object invisible and hide what is behind it

[gazm]

Hi,

I'm afraid I am a newbie to Houdini (6 weeks), and am stuck on what I hope will be an easy conundrum for any experienced user. I have a scene with a fire creeping through a door, the scene is live action and I shall be compositing the pyro onto it. I have created some geometry to symbolise the door but I would like to render the fire only when it's in front of the geometry without the geometry also being rendered.

I hope this makes sense, basically I want a shader that is invisible and makes anything behind it invisible also.

Thanks.

[mikelyndon]

Hey.

It's really simple. At the object level of the door in the render tab, turn on "Matte shading". This will create a hold out for the door.

Mike.

[gazm]

Ah thank you! That really is a simple solution. I am making progress with Houdini, but it's a steep slope and I have little rubber on my shoes.

Thanks again.