Using the PointOnSurface-node with particles

[mads-tuxen]

Hi all gifted freinds and foes!

Im trying to make some instanced particles stick to a surface and point in the normal of the surface during deformations. Like spikes or scales or somthing. Could be nice couldn

[mads-tuxen]

I tried using the arraymapper node, feeding it with the goalU and V, and then use the pointOnSurface as compute input. Then conected the normal form the Point on surface to the computenode colour. The out-colourPP of the arraymapper to a custom vector-attribute caled "norm", and then in the instancer make the aim "norm".
But it still noes not work. My norm valuePP is 0.0.0 for all the particles.

Should work shouldn

[joojaa]

No it wouldnt work!

[mads-tuxen]

Why not Joojaa?

I cant make it work but why not?
Looks so good i think.....

[joojaa]

It has to do with how the nodes are evaluated... But im pretty sure you couldnt get that to work. But you can force this behaivour with an expression if you so wish!

But I could allways give it a brief try...

But there is a commercial plug that could make this kind of stuff possible.

[mads-tuxen]

I tried to look at the Paint geometry-script and the resulting nodes and they have one pointonsurfacenode for each peace of geometry.

Is it because the PointOnSurface only evaluates once? or why.

And by the way whats the name of the plug?

Thanks for your interest
Mads

[joojaa]

Well not exactly... But since there are many different instances each needs to be fed with a different value.

It is evaluated on demand but, the way you extract the info is a bit questionable. you would need atleast 3 ramps to accomplish this (3 corinate values) and even then it would be a bit coplicated. And theres no guarantee it will work in either case. Since it could get evaluated a bit wierdly (remeber the ramps are independent of eachoter in evaluation time).

But it could be done by moving around a locator with a particle expression... and reading the results. YOu may need to refresh the calculation tough, and this might be a sow way of doing this. BUt stroika might do it quite well...