Situation is this: I have a space scene with a space station and a planet. Space station has a glowing engine and planet uses nodes, too. There are two scenes: One with the ship and one with the planet and space background. These two scenes are combined with alpha over node (see the image of nodes.)
Problem is this: The glow appears only in front of the non-glowing space station, but not in front of space background (see the image created with MS Paint 
). Iāve tried mix, screen etc. nodes but alpha over gives the best result so far. This little problem still bothers me. What is best node to do this? The glow effect is done with adding a different IndexOB value to glowing objects and then combining the glowing and non-glowing objects with a screen node.
May I suggest using a glowing object, eg smoke/ fire sim or even just a few planes normal to the camera, eg billboard particles.
If you really want to do this with nodes then make an alpha channel out of your glow render, apply that to the glow render and then do zcombine
Hm, Iād like to try with nodes. So, I tried with the Zcombine nodeā¦ but it didnāt work. It still looks the same (see the image). So, how do I āmake an alpha channel out of your glow renderā? I see that thereās a alpha out in the Renderlayer node, but where do I insert it to? The Zcombine node doesnāt have an alpha input, only Z and imageā¦
so, how to do this? --> āapply that to the glow render and then do zcombineā
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Not sure how you are seting up your āglowā material, but how I would do this is:
Separate the glowing objects to another layer, and use a renderlayer to create an image of them only.
Pass this through a blur node and/or a glare node etc, to get the amount and shape of glow that you want.
Render the whole scene, including the glowing objects, using a second renderlayer, with āemitā turned off ( in 2.5 you can do both from the same renderlayer, as separate outputs) then use a mix node to āaddā the glow over the original image.
If you need foreground objects to occlude the glow, then render them separately, and use the z-combine node with the background/glowing objects z data and the foreground objects z data. This will force the node to assume that the glow is coming from a z distance the same as the image it is superimposed over, so the foreground will occlude it.
HTH
Incidentally, windows wonāt āglowā in space, only exhausts etc., as there is no air to scatter the light and make the glow.
Matt
Thereās a problem when I separate glowing objects to another layer: Everything, what should be in front of the glowing objects, are behind the glowing objects. Normally I do the glow like this: add a pass index of 1 to glowing objects and add glow with indexOB out, adding it to the whole scene (all except the background planet in one render layer!) with an add node. After that I would combine the space ship and planet with alphaover or zcombine node. See the image for my node setup, and tell, what is wrong.
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So, is it even possible to make an effect like that with nodes? Should I use sequence editor too, or what?
Solved the problem with nodes: I just add the glow effect with add or mix node AFTER I have combined the two scenes with alpha over or zcombine node.
Please elaborate. Just as you described your problem in detail, please describe the solution in as much or more detail. (You are writing for the folks who, months or even years hence, will āstumble uponā this thread and hope that it does not end with, āyep! I solved it! Bye!ā :rolleyes:
