newbie question regarding matte order

[andromeda_girl]

hello,
i am new to combustion and have a simple problem that i cannot resolve…

i am hopeful that someone here can show me a remarkably simple way to go about this…

what i have is 2 seperately rendered elements, which have alpha channels.
they are regular 32 bit files- not rla or rpf format: no Z depth information to them.

i need them to swap who’s in front partway through the shot.

ok- for example, imagine two spaceships.

#1 is in the foreground, #2 in the background.
i need #2 to change it’s position so that it is in the foreground, making #1 in the background halfway through the shot- as if one flew past the other, crossing it’s path.

using my usual compositing application, all i do is animate the z depth setting and voila! (yes, the renders have no z depth information to them but this works anyway as if they did)

however i am having a big problem accomplishing this in combustion.
i am hopeful of finding a simlar tool setting so i can do the very same thing. so far, no such luck.

i imaging that combustion can do the very same thing, and just as easily too… all i need is for someone to let me know how to go about this 😉

i look forward to a brilliant answer from one of you regular combustion users out there 😀

thank you all, much appreciated!

~A.

[nanuk]

Sorry, i don´t really get your problem. Could you explain it in another way?

Greetz Nanuk

[Timor]

if i got you right:
just split the layer that was in the bg the moment it is not covert by the other spaceship.
move the second part of your animation on top of the foregorund spaceship. it will now cover the foreground spaceship…

voila, your done!

hope this helps.

timor kardum

– omgraphix.de –

[andromeda_girl]

ok i will try and explain this again…

two seperate 3D rendered elements:
both are space-ships for example.

one of them is in front of the other, obscuring it, as in on top of it layer-wise if you prefer to think of it that way.

both ships change position partway through the shot:
now the one that WAS in the background is in front of, or covering, or obscuring, the ship that was previously in front.

because the foreground ship is naturally on top of the other layers-wise, it’s layer- position makes the background ship not go in front of the other- the background ship is naturally still in the background, it will always be in the background because in the layers stack, the other ship is above it.

the idea of making duplicate elements and layering them on top of the foreground elements, and animating their visibility or adjusting their in and out points is unfortunately an impractical method- when you have a composite with dozens of ship renders, each comprised of four or five seperate render passes (such as key, fill, lighhts, engine glows, reflections, etc.) …the prospect of adding duplicate copies of all those elements for EACH ship render and layer them differently just overly and un-necessarily complicates the comp, among other things.

i simplified my description of the shots just to illustrate the point without having to get lengthy like this- two ships, swapping layer-positioning, each taking their turn obscuring the other is essentially all i need.

therefore, some far more elegant technique of swapping their positions must be possible, something that involves either reversing their input order or having a z depth perameter inverted.

there simply MUST be an easy peasy way to do this- there has to be a way to get combustion to swap the input order of the ship renders.

i hope i have managed to explain this more fully, and appreciate any help.
thanks.
~A.

[andromeda_girl]

i thought there had to be an easy way…

the transfer mode can be animated.

thing is, the other day i tried animating this setting and it did not work:
but when you go into the timeline and set keys manually, then it does work. glad i tried that.

it would, however, be nice to know if there are any other methods that work.

~A.

[nanuk]

why don´t you just animate the layers on the z-axis? a value of -0.1 should do. if you got multiple layers for each “spaceship” you can parent them or group them, so that you don´t have to animate each layer of one spaceship. or you can link the z-channnel of every layer. Or you can switch mattes with set matte operator and stencil the foreground spaceship with the matte of the background spaceship. Or you can switch mattes with set mat and blend between the mattes.

Hope it helps.

Nanuk

[andromeda_girl]

thanks for the advice, i think i have plenty to go on.
the Z axis idea was onbe i was wondering about myself.

until i found out i can group layers, i thought it might be too much effort but it sounds reasonable now.
appreciate the feedback.

~A.

[nanuk]

No problem. Hope ypu will get your spaceships flying now.

Greetz Nanuk

[Author]

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