Let it snow, let it snow

[Per-Anders]

it really depends on what ind of snow you're after. what i sometimes use are what i term sprites, which is basically i make a single poly object on the z-plane (a quad, rather than a tri) and i apply a Look at Camera expression tag to it. then i put this in my emitter, and i make a material that's got a fair ammount of luminescence to it (light blueish) and in the alpha channel i put in a bhodinut gradient, and i set the gradient to be 2d circular and i apply that to my polygon object. then i'd just make the emitter emit from a large area above the scene and put an some good turbulence and a little gravity. play around really because different settings work better or worse for different scenes. maybe i should do a tute on the prite method as it seems not many poeple use this, and it speeds up renders no end, especially when you need to do smoke and the like... hmm. oh and before i forget you might want to up the ray depth (in the render settings dialog box) otherwise you might start getting strange black edges where snowflakes overlap. the other method for less difuse snowflakes is to make a single poly as above, then map a nice snowflake texture into the alpha and don't add a look at camera expression tag to it. then make sure that the particles are spinning a little to get a nice snowflakes falling type effect.

[kiwi]

Your method is really interesting Per :thumbsup: ....a tute would be really cool, when you get time to do one that is :)


Stu.

[Per-Anders]

i'll try, you can fake volumetrics with my method too... it's not difficult, basically a further version of the carpet that i made ages ago on these threads. multiple layers of a 3d texture... i'll explain more later. on my site when i get a chance. it's nothing complex, but you can do some really cool things with it, i'll make a little tutorial (and it works with 7 as well as 8). i have other tutorials i have to finish also. and real work. so much to do so little time to do it in.

[bjotto]

In some case you have to up the shadow depth to 'cause otherwise there will be no shadows behind transperant stuff

[Bucko]

The technique mentioned by mdm_sadie is called billboarding when done in computer games and can be used to do lots of things.
You can have two identical emitters, one with billboards facing camera with alphas etc and one facing the sun/light not visible to camera but casting shadows to get reasonable smoke that will render MUCH faster than Pyrocluster.

One has to remember that the target expression will not be applied to each individual particle but only the particle original at its location prior to being used by the emitter. You cannot therefore fly through your smoke or even get very close to it before the trick is blown.

[Per-Anders]

yup :) but i think with thinking particles there may be a way to do this on a per particle basis so the illusion shouldnt be blown till you're really up close (when you get troubles as particles can spin into the scene where you don't want them to). but you can also use xpresso to link the object that you need to face the camera to the camera so it's always dead in front of the camer (all the particles rotate according to this one object) and because the c4d cameras don't have lens distortion then it sort of works out ok.

unfortunately pyrocluster doesn't have the ability to take slices or do a proper "sprite" mode like certain other volumetric voxel systems can. (they take a slice or a number of slices of a volumetric shape ), so you have to make little workarounds, this one does work pretty well.

[flingster]

mdme_sadie: a tut would be cool...i suppose you could do rain as well as snow with this technique?

knowing nothing about pyrocluster does this mean that you couldn't get realistic snow from pyrocluster? or are we just thinking quick here?

[Bucko]

How do one apply pyroclusters to anything but particles?
As far as I could tell Thinking Particles (TP) uses objects such as nulls etc and therefore we cannot use TP to get proper per particle facing the camera billboards.

/ Backman aka Bucko

[Per-Anders]

just look at the tte on my site (go to the tips section) thinking particles sprites.

it gives proper "billboard" camera facing.

the particles aren't pyrocluster though, you aren't limited to what pyrocluster can achieve, you can use standard sla procedurals or just image maps.

as for rain yes it's easy enough, you can ether make a raindrop image on your sprite, or you can use the tprolling node to stretch the particles in the direction of travel. (you could even use small spheres in this case) make the particles move fast and you should see the effect you want. tp handles motion blur properly too it owuld appear (unlike the old particle system).

[Per-Anders]

(edit) you can't apply pyro to anything other than particles it appears :/ another area hypervoxels beats it hands down.

[Srek]

Hi,
Pyrocluster does only work with particles. Both the classic particle system and TP will work.
In TP you have to assign the PC material to the "Particle Geometry" object.

Regards
Srek

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