[Gopher-devs] Effects and their I/O

[Olivier D. <oli...@ca...>]

In trying to work out some design for Gopher, I wrote the following
requirement:

- An effect has 0 or more input buffers and 1 or more output buffers.

As an example, a plasma that is drawn from intersections of cosine lookups
need no input buffers and will (usually) produce output for one output
buffer.  You control the plasma with a few parameters.

There are also effects that manipulate/distort one input and produce one
output.  (ie: raindrop effect, overlaying a logo, etc..)

Then there are effects that take two input buffers, blend them together
somehow and produce one output.

I've even written an effect that takes three input buffers and uses the
first two to decide how to third one will be distorted/rendered in the
output buffer.

So far, all these effects have only had one output.


I'm looking for a case where multiple outputs are necessary and would mean
uncomfortable (impossible?) work-arounds if the requirement was re-written
as:

- An effect has 0 or more input buffers and exactly 1 output buffer


ie:  an effect that takes a RGB input buffer and produces an output buffer
for each of the primary colours.  Would it be the case that the three
seperate "colour buffers" would be fed to three seperate effects or do they
just end up being translated/offset from each other and then blended back,
something the effect could have done on its own using only one input and one
output buffer?


It looks as though it would be easier if effects only had one output,
because then we could tie the output to a track, a bit like DemoPaja ties
effects to "Layers".  This means authoring the output of an effect is
implicit and all a user needs to do is wire the inputs, although my mind is
blank as to a good/intuitive way of allowing users to do this in the same
interface that they author effect parameters.  (ie:  should it be arrows
crossing tracks or you pick numbers or it is based on the order of the
channels or what?)


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Olivier A. Dagenais - Software Architect and Developer