Multistreak Particles

[Bernard]

Hello,

Is it possible to create a multi streak particles effect with Houdini, like the example in the link (done in Maya) ?

http://www.cgshelf.com/tutorials_ringfire.php

thanks,

bern

[steven]

Hello,

Is it possible to create a multi streak particles effect with Houdini, like the example in the link (done in Maya) ?

http://www.cgshelf.com/tutorials_ringfire.php

thanks,

bern

Use a Circle as your source and maybe an Orbit POP?

[GallenWolf]

Long time since I used Maya, but I remember the Multlistreak is basically a few points surrounding/representing a particle? I think you can probably like use a copy SOP to instance a group of points onto your particle system and render that.

Unfortunately, the tutorial uses Maya's Hardware Render Buffer - probably in multipass mode - I'm not sure if it can be done out of the box with Houdini. I haven't tried it yet but perhaps you could render out multiple sequences of the particle system with different seed values and then composite them in cops? You'll probably want low luminance values and slowly add them over in COPs.

Alvin

[old school]

You can use the Point SOP to add attractor forces on to a circle.

As for hardware rendering, there isn't a canned solution out of the box. Sprites...

As for accumulating the color, there are a few ways to do this from the Proximity POP to using point clouds.

I attached a file that uses both the Point SOP's force folder to add line forces to the circle then the Proximity POP to add an attribute which counts the number of points in a spherical region to each point. That is used to simply brighten the points and also to increase the size of the instance geometry. Lots of potential for tweaking.

ring_of_fire.hip

[Bernard]

You can use the Point SOP to add attractor forces on to a circle.

As for hardware rendering, there isn't a canned solution out of the box. Sprites...

As for accumulating the color, there are a few ways to do this from the Proximity POP to using point clouds.

I attached a file that uses both the Point SOP's force folder to add line forces to the circle then the Proximity POP to add an attribute which counts the number of points in a spherical region to each point. That is used to simply brighten the points and also to increase the size of the instance geometry. Lots of potential for tweaking.

Thanks old school, that's great!

[ihab]

For color accumulation you can create a simple shader in vops that uses the particle colors. It can be a constant shader for example . If you do not premultiply the color with opacity in the shader and the opacity is less than 1 you'll have a color accumulation effect. Here's how to do it quickly.

1. go to vops and create a vex surface shader

2. MMB on the CF button in the output node and choose create parameter.

3. Rename the parameter name to clr (could be anything)

4.do the same with OF

5.create a shop from the vop you just created and set the opacity to .5

6. in your sops create an attibute (vector) and name it clr and set its value to $CR , $CG and $CB

7. attach the shader

VOILA!

cheers

Edited May 19, 2007 by ihab

[MIguel P]

Nother trick for doing that increasing the Transmit color in a VEX Super Material. This creates really cool effects.