record creationtime,endtime attr of points

[Benyee]

A random pattern(red) spreading and then fade out on a ploy plane(black),

if a point becomes red(say $CR>.1),assign its creationtime attr value with current glabal time(in second) and keep it;

...

if a point becomes black($CR<=.1) by fading out,record the endtime attr with current time and keep it;

During this,record its age attr.

How to set up the process,thanks.

[Erik_JE]

Use a VOPPOP.

Use one attribute storing creationtime and initialize it to -1. In the VOPPOP compare if it have been initialized. If not set it's creationtime as soon as it turns red. Keep a second attribute that you update whenever it is red. Calculate the age by subtracting the creationtime from the endtime.

EDIT: This was trickier than I thought.

EDIT2: I believe the attached file is what you wan't. There is probably a more elegant way of doing it but this calculates the age while the particle is red and otherwise returns 0.

age.hipnc

Edited October 19, 2011 by Erik_JE

[Benyee]

Thanks,this give me some tips.

Actually,I wanna record those attrs of points of a surface.

[Erik_JE]

This approach will not work for a surface as it uses preserve groups which are unique for particles.

For doing it on a surface geometry i believe you need to bring it into a SOPSolver to be able to accumulate the age. Not my strong side, maybe someone else knows.

[CTEffects]

Thanks,this give me some tips.

Actually,I wanna record those attrs of points of a surface.

Here's my approach which uses a SOP Solver.

It allows you to specify a threshold which will record a birthtime if it goes above and a deathtime if it goes back under.

You can also invert this behavior if desired.

I tried to make this as flexible, robust, and modular as possible. So copying the asset into your scene should be fairly painless.

recordattrib3.hip

[Benyee]

Here's my approach which uses a SOP Solver.

It allows you to specify a threshold which will record a birthtime if it goes above and a deathtime if it goes back under.

You can also invert this behavior if desired.

I tried to make this as flexible, robust, and modular as possible. So copying the asset into your scene should be fairly painless.

Hi,CTEffects.Thank you for the helps,pretty good job.

And so I got a simplified version with less logics.record_birth_attrib.hip

[sparkChan]

hi, I do the same thing using chop, and I think it's more accurate than your method.

record_birth_attrib.hipnc

[Benyee]

But...

How to get extreme attrib value(max/min) of points at any frame?

For example,the oldest life value at global frame 100?

Thanks,guys.

Edited November 6, 2011 by Benyee