Image sequence for a mask

[JimB]

I need to figure out how to create clouds that rotate around a set point to create a vortex effect. I have an idea to do with using an image sequence as a mask, mixed with other procedural settings being animated. I know it's been mentioned before but not even Oshyan seemed sure.

Animating the density fractal's warp doesn't pass muster so far.

Does anyone happen to know what the method is for using a sequence as an image mask, not just a still?

Thanks.

P.S., if anyone knows how to rotate a density fractal around the Y axis, feel free to let me know   

[Tangled-Universe]

Maybe this?:

http://forums.planetside.co.uk/index.php?topic=2220.msg23499#msg23499

It's supposed to be used for terrains but it should work for clouds also then...

Martin

[JimB]

Thanks for that Martin, but it unfortunately seems to do nothing to the clouds.

[old_blaggard]

Interestingly enough, I've spent the past week or so working on generating a tornado from within Terragen, and I have put together a function set for generic rotations about the y-axis (or x or z, or any line really).  I'm not sure if it will work on image masks, though - I've only tested it on function-generated noise.  I recently uploaded it to Ashundar: http://www.ashundar.com/index.php?action=tpmod;dl=item384
The clip uses a straight line, but that can trivially be replaced with Perlin Noise.

[rcallicotte]

Thanks, o_b.  I'm going to try it out.

[Matt]

Image map sequences:

http://forums.planetside.co.uk/index.php?topic=3825.msg40331#msg40331

Animated rotation of clouds should be possible using functions. I have managed to do something like this in the past; I'll see if I can find it.

Matt

[JimB]

Interestingly enough, ...

Cheers O-B. I've given it a run through and plugged everything into everything and can't seem to get the desired result. Appreciate your time, though.

Image map sequences:

http://forums.planetside.co.uk/index.php?topic=3825.msg40331#msg40331

Animated rotation of clouds should be possible using functions. I have managed to do something like this in the past; I'll see if I can find it.

Thanks for that. I found that thread a bit earlier and have been mulling over the most expedient way to set up the command line renders. I'd really appreciate seeing if there's a way of doing the rotation with functions though. Ta.

Errrmmm, shouldn't you be in bed.......?

[nikita]

What about using an image as density function and rotate the projecting camera?

(The method I described in that threads only works for displacement, though I didn't notice that restriction before)

[nikita]

Here is another way of rotating clouds. (See the attached network)
The idea is to use 3D perlin noise. The advantage is, and I'll ignore the math here and give a simple explanation, that it lets you specify a reference point. Usually that'll be a Get position in texture node.
Now rotate the reference point and you rotate the noise -> voilà.

The downside is, that you have to stack several perlin noises on top of each other to get a convincing result.

[JimB]

Nikita, thanks very much for that. Very impressive for its simplicity and result.

Is there no way to use a bog standard cloud Density Fractal instead of a Perlin scalar function in this manner, if you needed to take a 'look' that was already designed and rotate it around the Y axis?

[nikita]

If there is a way, it's probably very exotic or the total function madness.

One could translate the density fractal into displacement, rotate that displacement using the method i described in that thread/article mentioned above and the translate it back into a scalar using get altitude or something similar.
But you'd have to use a second planet to separate this displacement stuff and the atmosphere/cloud layers from the normal planet, where you'd have your terrain and surface. Otherwise it won't work because get altitude is a per object value afaik.
edit: you'll lose the Y-dimension this way


I guess the easiest way to solve this is to kindly ask Matt for implementing that reference point mechanism into the normal fractal shaders too. I may be wrong, but this shouldn't be hard to do. In fact it's not like this feature had to be specifically implemented for Perlin 3D scalar node. It's more like the feature has been disabled in the fractal nodes who automatically chose the right coordinates.
It's only adding/changing 4 lines of code. (Judging from the sample implementations in Texturing and Modeling and Perlin's homepage)
[end of "I may be wrong"]

[mr-miley]

JimB

Hi there. I'm probably talking out of my backside but... Do you already have a image sequence you want to use for a mask? If so, you could always do it frame at a time using the relevant image in the sequence as a map for the relating frame in the animation. I know it wouldnt be automated but at least you could do it. If your sequence frame numbers ar incrimental could you not use a function to increment the image map filename by 1 for each frame?

If I am talking rubbish sorry about that

Miles

[Mr_Lamppost]

Is there no way to use a bog standard cloud Density Fractal instead of a Perlin scalar function in this manner, if you needed to take a 'look' that was already designed and rotate it around the Y axis?

Not that I could find. There was quite a bit of work done on rotating clouds earlier in the year:

http://forums.planetside.co.uk/index.php?topic=3227.30

That thread is concerned with hurricanes but you may be able to dig something useful out of the shared files. 

[JimB]

Miles, no one's talking rubbish and thanks for the suggestion. 

Mr-L, cheers for the reminder as well. I'll look into it.