"Hugo Asm" <hua### [at] post3teledk> wrote in message
news:3fcbb4b6$1@news.povray.org...
| > You or I could write a meshing algorithm specifically for snow
|
| Would probably be a good idea ...

I really don't have the time, but I am tempted to give it a shot. Out of
curiosity, what algorithm did you use to determine the location and size
of your snow blobs? I've never seen snow.

On the original topic of this thread. That is a quite nice ball of
rings, but it would have been pretty simple and faster rendering as a
mesh also.

 -Shay

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> what algorithm did you use to determine the location and size
> of your snow blobs? I've never seen snow.

You've never seen snow? I probably shouldn't take this literally.

Well, I used Gilles Tran's "makesnow.inc" at first, then modified it to
speed up parsing but the idea is still a very simple approximation:

I declare a direction vector that simulates wind and gravity, such as
 <-1, -1, 0>  which would tend to cover the top and right side of an object
(assuming y is height). The size of each particle is random but has a
minimum & maximum limit. I use the "trace" feature to shoot rays at an
object, which in my case is an imported mesh2... Gilles' macro can be found
here: http://www.oyonale.com/ressources/downloads/makesnow.inc

I know you're skilled when it comes to handling triangles - so good luck -
the project is interesting - but feel free to stop when you want to.

Best wishes,
Hugo

PS: we should probably continue the thread somewhere else.

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Hugo Asm wrote:
>>what algorithm did you use to determine the location and size
>>of your snow blobs? I've never seen snow.
> 
> 
> You've never seen snow? I probably shouldn't take this literally.
> 

Saw the first snow for the year this morning.  They were filming 
something or other on the corner and had snowmaking equipment out to put 
snow in the scene.

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hua### [at] post3teledk news:3fcbb4b6$1@news.povray.org

> Would probably be a good idea ... maybe even an isosurface would be
> quicker. 

No, mesh is quicker. I.e. inside my wax figures are over 200.000 particles. 

-- 
#macro g(U,V)(.4*abs(sin(9*sqrt(pow(x-U,2)+pow(y-V,2))))*pow(1-min(1,(sqrt(
pow(x-U,2)+pow(y-V,2))*.3)),2)+.9)#end#macro p(c)#if(c>1)#local l=mod(c,100
);g(2*div(l,10)-8,2*mod(l,10)-8)*p(div(c,100))#else 1#end#end light_source{
y 2}sphere{z*20 9pigment{function{p(26252423)*p(36455644)*p(66656463)}}}//M

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"Hugo Asm" <hua### [at] post3teledk> wrote in message
news:3fcbc6d3$1@news.povray.org...
|
| You've never seen snow? I probably shouldn't take
| this literally.

I meant it literally. It has snowed a handful of times here, but it
melts as soon as it touches the ground.

|
| the project is interesting

I put something together last night. I guess it looked like a blob mesh
would on a little isosurface mauntain range I made. That is, it looked
like white, puffy grass. The parse was about half an hour, but the
render time is measured in minutes, not days. I took a look at Gilles
website and saw that he had noticed the same problem, that the algorithm
only produces good results in small patches on tree limbs and such. I
built the mesh so that it can be further refined (within the limits of
fp precision) so the with enough memory, an acceptable snow might be
made on a jagged enough mountain. I would guess that mountains don't get
snow-covered in one pass anyway, so it might be that this algorithm
would never produce realistic results on a large object.

|
| PS: we should probably continue the thread somewhere else.

I set followups to p.gen if you have any further comment.

 -Shay

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