Understanding VEXpression

[art3mis]

Can any VEXpression experts help me understand the following used in an Attribute Create node. Its from a .hip that demos light instancing. What exactly does the following return?      

 

/obj/light`int(fit01(rand($PT+1541)*2,1,2))`

 

[konstantin magnus]

/obj/light`int(fit01(rand($PT+1541)*2,1,2))`

Start reading it from the center of the brackets:

(rand($PT+1541) // A random value between 0.0 and 1.0 is created based on the point number ($PT) + an additional seed value (1541)
*2 // The random value gets multiplied 2, so now it´s between 0.0 and 2.0
fit01( XXX ,1,2)) // This get fitted from 0.0 - 1.0 to 1.0 - 2.0 (so multiplying it by 2 has not made much sense imho)
int( XXX ) // The whole thing is casted to an integer, so in this case either 1 or 2
` XXX ` // The back ticks probably turn this into a string, so you can combine it with:
/obj/light

So I guess it would switch between two light sources named light1 and light 2.

Edited July 29, 2018 by konstantin magnus

[Noobini]

methinks be careful with int()

It's TRUNCATING....not just casting to type int.

So just randomly....round(1.8) = 2

but int(1.8) = 1

To me the original method is a bit 'convoluted'.....where you'd need to digest this bit of info:

fit01(num, newmin, newmax)

Returns a number between newmin and newmax that is relative to num in the range between 0 and 1. If the value is outside the 0 to 1 it will be clamped to the new range.

...the 'outside' range bit...

 

So I've fooled around with other methods...personally, I prefer the last....where you know it's one or the other..so simply add 1..assuming object names are obj1 and obj2...

fit.hipnc

Edited July 30, 2018 by Noobini

[art3mis]

Thanks! Certainly seems convoluted if all we need to do is randomly switch between 1 & 2 ?