okay this is another weird one

heres what I want to do:

1) a single camera (first camera) pointed at some animation of geometry. Let's say a sphere moving up and down.

2) Take what the first camera is seeing and import into it into Cops.

3) Take that Cop information and feed into the texture parameter of a shop. So the shop doesn't get its info from a “file texture”, but instead gets it from the first camera. This way the camera is used as a “texture generator”.

THIS IS WHAT I“M AFTER. A camera that can generate textures (and be altered in Cops) that can be applied in Shops. Doing this as a post-render effect WILL NOT WORK.

4) Then I will set up a second camera that can only see a new 3D object (let's say a cube) with the first camera's ”viewing information“ input mapped onto it as a material/texture. I imagine the second camera will need to run $F-1 to make this work… so I have to be able to set up the second camera to read information a frame later. THIS IS ACTUALLY VERY CRUCIAL FOR WHAT I'M AFTER. A camera with a one frame delay. Like a animatable ”Cache“ value for the ”second camera“.

so there are a few issues here

a) getting the cameras ”view“ information into Cops.

b) Exporting that color/texure information from cops into a Shop.

c) Setting up a secondary camera that is capable of a $F-1 lag.
This will allow the ”secondary camera" to see what is mapped on a 3D object (from the first camera) at a one frame lag.

I am nuts
I have my reasons
Anyone care to help?
Freaks welcome!

thanks for the time

Jim

Can you just shift your COP data by one frame?

Edward… as always your suggestions are great!

I “edited” my post to explain why this would not work.

Mind you I am a self-proclaimed novice.
That said I do my best to help other “of my kind” with long drawn out explainations.

I don't think your solution will work given what I've re-written in this post.
Mind you I am such a novice that I have yet to figure out (with the latest version of Houdini) how to even get Cop info into a Shop.


thanks

Jim

Shops and textures are the mantra area. Mantra can't “see” what is going on in Houdini. It just read archive (ifd, geo, pic) and render file. So your problem is more a scripting challenge then pure Houdini setup. As I suppose, you need script which will go through several steps for every frame:

1. manage your texture render cam in COPS via ROP render
2. then postprocess frame in COPs
3. render final COP
4. and then fireup new render with previously rendered frame as a texture on your object

and just like that frame by frame.

quite easy, but I still don't understand why you just can't render your texture first, then aply texture and render it again?


cheers,
SYmek

Jim Ellis 2001
okay this is another weird one


so there are a few issues here

a) getting the cameras “view” information into Cops.

b) Exporting that color/texure information from cops into a Shop.

c) Setting up a secondary camera that is capable of a $F-1 lag.
This will allow the “secondary camera” to see what is mapped on a 3D object (from the first camera) at a one frame lag.

For a) use a render cop - or set up two mantras which are dependent on each other, ie wire them together. If you want to do some processing in cops then you will need a comp output wired inbetween the two normal mantras

For b) use the op: syntax, so for example where you would normally put a file path put something like opimg/img1/foo

For c) for chops to grab the camera data and then offset it and export to your second camera


Does that cover it? Not 100% sure I follow what you need but hopefully this answers your specific questions.

So you want your second camera to grab the first camera's data at time $F-1 right? I'm not quite sure what “viewing information” you're trying to use in the second camera from the first. If it's just parameter values, you can use chf(“path_to_cam1”, $F-1) instead of ch().

Thanks to everyone for the ideas, clues, and solutions!

Simon your response was crucial in me getting what I was after!
I nailed the first steps because of your assistance.
Now I can continue on.
Thanks again guys!

all my best

Jim

Are you creating some sort of crazy 1970 feedback video effect?

:roll: :wink: :idea:

yeah… something like that.
I'll show you once I really get it going
if you're down.