PF source Mental Ray 2014 Max Design

[grue1970]

hello. was playing around with pf source for some heavy distribution of ground-cover (grasses).  i found that there is somewhat of a limit, 5,000,000 faces/vertexes per mesh.

i looked at the options for creating multiple meshes with x number of particles, 1 mesh only and one mesh per particle.

the manual mentions that one mesh per particle can have a limit in that it won't create new particles after frame 1?

in my playing around for example, i had a clump of grasses with about 8,000 faces/vertexes.  then i did an instance distribution on an object (plane).  1,000 particles created at frame 0.  then 5,000 particles.  of course i hit that limit of 5,000,000 faces/vertexes.  but with one mesh per particle MR rendered it up no problem.

back to the question, so the limitation they are talking about is that one mesh per particle you have to have all your particles born at frame zero?

[jonathan.matthews]

Hello-

I am not sure on your question.  I will ask our development team.  

In regards to creating grass I would use Hair and Fur in 3ds Max.

https://www.youtube.com/watch?v=38yj9xv8-cA

Best Regards.

[jonathan.matthews · Accepted solution]

Hello.  Here is the response I recieved from one of our developers:

Yes, with the options "one mesh per particle" and "multi-particle meshes" (I don't recall exactly the name of the options, overall idea is either to have a mesh per particle, or define a number of particles per mesh; in both cases representing a particle system object with multiple meshes), all particle have to be born at frame zero.

The limitation comes from the Max SDK. It has a method for a renderer to define how many meshes an object has for rendering ( something line NumRenderMeshes ). Unfortunately, the method does not have arguments to define time. Therefore, an object is asked only once how many meshes it has. Therefore, for a particle system that may have variable number of particles, it has only one chance to answer this call. Hence the limitation.

Have a good day.

[grue1970]

get an unexpected error trying to accept as solution. but kudo worked ok. anyway, thanks.

[jonathan.matthews]

No problem.  I received an email saying it was accepted as solution.  Have a great weekend.