1. #1

    Trying to tie the alpha of a cloud to a data source...

    I wanted a cloud to appear slowly, so I tied the alpha of that cloud to a linear curved data source that goes from 0 to 100 in 2 seconds. Really easy and it works perfectly when I press select in the editor.

    However, when I test the track, the cloud does not appear. At all. No matter what I do.

    I am 100% sure I set it up correctly, it works perfectly but only while editing.

    Why doesn't it work when testing the track?
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  2. #2

    Re: Trying to tie the alpha of a cloud to a data source...

    Changing particle properties affects only newly emitted particles. Clouds are emitted very rarely and they are alive for minutes before new ones appear.

    You can see it kinda working in the editor because it always refreshes the clouds when you change some property. You can see this refreshing in the changing of the clouds' positions.
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  3. #3

    Re: Trying to tie the alpha of a cloud to a data source...

    Originally Posted by Johannes
    Changing particle properties affects only newly emitted particles. Clouds are emitted very rarely and they are alive for minutes before new ones appear.

    You can see it kinda working in the editor because it always refreshes the clouds when you change some property. You can see this refreshing in the changing of the clouds' positions.
    Ah so I would have to wait for the cloud to "refresh" before I saw any changes in its alpha.

    Is there an alternative way I can do this then?
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  4. #4
    jook13's Avatar Senior Member
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    Re: Trying to tie the alpha of a cloud to a data source...

    Area condition tool, playing with the interpolation?
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  5. #5

    Re: Trying to tie the alpha of a cloud to a data source...

    Originally Posted by buttcheekofdeth
    Originally Posted by Johannes
    Changing particle properties affects only newly emitted particles. Clouds are emitted very rarely and they are alive for minutes before new ones appear.

    You can see it kinda working in the editor because it always refreshes the clouds when you change some property. You can see this refreshing in the changing of the clouds' positions.
    Ah so I would have to wait for the cloud to "refresh" before I saw any changes in its alpha.

    Is there an alternative way I can do this then?
    Exactly. I'm afraid not using the cloud effects.
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  6. #6

    Re: Trying to tie the alpha of a cloud to a data source...

    I was having this exact problem just last night. Good to see a very clear explanation of why it wasn't working!

    Oh well... now I need to think of another way of making crumbling dust (a ground explosion with sound disabled would work if it didn't have those sparks).
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  7. #7

    Re: Trying to tie the alpha of a cloud to a data source...

    Can't you tie a data source to clouds if you use area condition instead of track settings?

    Edit: sorry Jook. I'll read the whole thread next time
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  8. #8

    Re: Trying to tie the alpha of a cloud to a data source...

    Originally Posted by SeriousStu
    Oh well... now I need to think of another way of making crumbling dust (a ground explosion with sound disabled would work if it didn't have those sparks).
    I've been playing with something that could easily be tweaked to get what you're describing. Try the Slow Steam effect -- variation 2 works well. Set the particle color to something dark and saturated, like a rusty orange. Set the alpha to around 20 or so.

    You can probably change the alpha on the fly a lot better since steam is emitted more often. But even if this doesn't look right to you, you can do a lot of cool stuff.

    The trick is to make the steam effect move around a bit. I did this by attaching it to a dummy object by way of a rotational hinge. Then I had the dummy object follow the bike itself. The end result is that the steam swirls in a circle around the bike all the time. It looked fantastic once I tweaked all the values just right. When I'm flying down the track it's almost completely unnoticeable -- but when going slow, it starts to build up a bit.

    For "crumbling dust," I would maybe just check the physics box on the effect, and let it fall to the ground by itself. Try adding a large linear damping value (95+) to have it fall more slowly and naturally. This assumes the effect is within the physics bubble, of course.
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  9. #9

    Re: Trying to tie the alpha of a cloud to a data source...

    Oh yeah, course - as soon as I started to read your message I remembered I could have used an Area Effector to make the Steam particles drop instead of rise did initially try using the Slow Steam effect for dust but thought 'Pfft, that's dumb - dust doesn't naturally rise!').

    Thanks for the brain wave!
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  10. #10

    Re: Trying to tie the alpha of a cloud to a data source...

    Originally Posted by jook13
    Area condition tool, playing with the interpolation?
    Sorry I wasn't being clear enough. The cloud isn't in the sky, I'm using a cloud effect near the ground and I want it to appear slowly.

    Johannes, I kind of got it to work, but in a stupidly complicated way. I put 10 cloud effects next to each other, each one with a different alpha starting at 10, then 20, then 30, all the way up to 100. Then I used impulse delay filters to get the cloud with 10 alpha to appear for 0.1 seconds. Then it disappears, and the cloud with 20 alpha appears for 0.1 seconds. Then that one disappears, and the cloud with 30 alpha appears. Repeat until the cloud with 100 alpha appears, and then that one stays forever. It achieves the same effect, it's just choppier now.
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