rendering particles..

[Alexpdennis]

so i have these particles right,

i understand they render default all big and sphereical. i read in the help that you need to set up some stuff in POPs; in the solver, right now i have a render node that has blur and size parameters, but nothing shows up on the render. I also know that doing this in the un-cached DOP is not very economical. how in the heck to i set up these parameters (age, size, etc.) to work on a cache sim? should i have set up that kind of stuff pre-cache? sorry for the noobness, always appreciate any help i can get. thanks again.

[Fabiano Berlim]

Motion Blur - Particles need to be render with "velocity blur", since the point or poly count is not constant. To render an object with "velocity blur" you need an attribute called "v". This attribute must be from class "point" and type "vector". Don`t worry, all particles have it. Now go to the object, click in the tab render, then sampling and turn on "Geometry Velocity Blur". In the mantra output driver turn the "Allow Motion Blur" on.

The cool thing about it is that you can create your own custom v attribute and make motion blur even if the object is not moving.

Size - Size is created with the attribute pscale. Go to the object that is rendering the particles, create a node called "AttribCreate", the name must be pscale and just type in the Value field the size you want.

Age - To control how your particles dies, you need to change the "Life Expectancy" in your "Source" node.

Of course you can change anything after the simulation is done, but you need to understand attributes very well.

There are adicional tips here in the manual.

http://www.sidefx.com/docs/houdini12.1/particles/instancing_rendering

And here are all the attributes that mantra can find for particles and instancies.

http://www.sidefx.com/docs/houdini12.1/copy/instanceattrs

Happy Hollydays!!!

[Alexpdennis]

man thank you so much sir. happy holidays to you and yours. also really nice reel. that tornado is sick!!! thanks again

[Alexpdennis]

so i have to change age before i cache? sorry and thanks again

[anim]

you can change any attribute after cache if you wish, you can use any SOP that modifies attributes, however VOP SOP offers the most flexibility

I usually only care about age before caching particles, then in SOPs convert age to normalised life (0-1) by dividing age/lifespan

then I can easily base any other attribute(like pscale, Cd, Alpha, ...) on life so that it changes over the life of the particle using simple ramps

it of course depends on your needs

if you want to control dying after caching as well, you can cache with very high lifespan so that particles never die, then in SOPs you can randomize their lifespans, compute normalised life and delete every particle with life > 1, and set up all other attributes based on life or however you want

[Alexpdennis]

thank you so much sir. that ought to keep me. i cannot express my thankfulness enough. happy holidays