Tech Discussion: Frame Buffers


Hey my XSI friends.

I’ve been mulling over doing a series of technical discussions, and I figure I’d just get one started and see how it goes.

Frame Buffers

Do you utilize frame buffers? Frame buffers in Mental Ray seem to be a terrific means to reduce rendertimes by getting different output into separate image files, concurrently. Unfortunately they seem to also cause confusion - and to people who haven’t completely wrapped their heads around them - headaches.

In the 5.XX versions of XSI, frame buffers were available in a canned way, there were only pre-defined ones available, and (at least for me) many shaders made them unusable. Then CtrlStudio released a beta version of a collection of shaders that allowed for more flexible use of them in XSI. Unfortunately the development of the XSI version stopped.

In the 6.XX versions of XSI, frame buffers have been expanded upon… they are more flexible and are integrated into the useful (yet confusing to some) Render Manager interface.

So, tell us… do you make use of the frame buffers? How so? What have your experiences been? What tips, tricks, concerns can you share with the XSI users that frequent this community?

Please feel free to discuss any implementation you like - i.e. the Native implementations, or access granted by addons.

Thank you


Good idea Jason.

I use them constantly. It’s just way too good of a time saver to not use them. Once you understand how they work inside the rendertree (although I admit it’s a little confusing) it’s not too bad.

Does it make sense to make a video about rendertree usage?


Yes Please!

Also, how has this altered your use of passes? I’ve always found the pass system to be one of the best reasons to use XSI. Have passes taken a back seat to buffers? Should/can buffers be implemented in a similar way as the pass management system, rather than linked to nodes on the render tree?


with the newer implementation i think passes should be used for organization/object visibility/layering and then your framebuffers will be your seperate passes for each one of those organizations.

foreground pass - outputs foreground objects with amb,diff,spec,motion,custom mattes, etc all with the same coverage. so everything lines up.

same for midground and background.


Good question. I personally use both quite a bit and think they compliment each other instead of replacing one or the other.

Should/can buffers be implemented in a similar way as the pass management system, rather than linked to nodes on the render tree?

Not that I’m aware of.

Give me a little while on the video. I’m working on a pitch today.


Gene, that would be terrific. Let me know if you need a hosting mirror or anything.

Using 5.11, I’m pretty much stuck with ctrl_buffers… which is fine, as they do work… but I always feel like I’m spinning wheels when setting it up. I’m very interested to see how some of you approach the use of buffers.


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