[Bf-committers] Re: Re: render passes & workflow

[Ton Roosendaal]

Hi,

A unique automatic ID for every Object is a nice idea, but needs to be  
carefully implemented, so it won't change during the course of a  
project. Imagine you setup a scene first, and then decide to add a  
scene 'set' backdrop, or add/remove objects.
I can check on creating a hash function that turns the Object name +  
library name into a unique ID though.

It seems to me that both Matt and GSR have valid points. So, a  
'automatic ID' generator can be a render option, to create unique but  
permanent IDs for Objects that had no manual ID set.

Internally it still should be stored as simple (1 float/int) ID values  
though, so you can sample the pass still to check ID tags. For the  
compositor I can add a node to extract mask information efficiently  
from the ID buffer, into a nicely antialised or blurred alpha mask.  
That's more efficient than using Matte-key nodes, although - for  
exporting - I can add the option turning it all into pseudo-random  
colors.

Here's what this node can look like:

ID Mask Node:
- input socket: ID buffer (single value buffer)
- button options:
   - ID value (or min/max range?)
   - Antialias option
   - blur level
- output socket: Alpha mask
- output socket: Pseudo Random colors (ignoring button options)

How about that?

-Ton-


On 7 Dec, 2006, at 6:17, GSR wrote:

> Hi,
> matt at mke3.net (2006-12-07 at 1453.26 +1100):
>> Sure, and that's not what the Object ID channel is best used for. If
>> you want to operate on a number of objects together, use a render
>> layer, it's much more suited to the task. Object ID channels are best
>> for isolating individual things that you see later after rendering
>> and would like to make quick small adjustments to, on an individual
>> basis.
>
> The user can have ten objects that require such tweak, if he planned
> IDs ahead, he saves time. Otherwise nothing changes compared to fully
> random colour, he can do a big node network or wait for new render
> layer to be computed. The comments were just an improvement on top of
> your idea, increasing flexibility and user control, allowing changes
> from single object to all objects in the frame (and enabling per
> object variations by being the base for DupliMats concept, which was
> there in global terms but required a reliable ID system).
>
> It just changes random fixed colour to random colour on create that is
> modifiable later (with some details about how it could be done in the
> code). A small change, that you do not have to use if do not want,
> providing big wins down the road.
>
> GSR
>
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Ton Roosendaal  Blender Foundation ton at blender.org  
http://www.blender.org