VOP inner Code

[rob]

vector $myP = $isconnected_P  ? $P : P;
vector $myN = $isconnected_N  ? $N : normalize(frontface(N, I));

This is a snippet of inner code from a vop and I just wanted clarification of what it means

vector $position = $P; I would use this normally

vector $position  = $isconnected_P ?$P :P;

I am not sure about this and why its even needed as if P , N are not connected its hardley going to work

$isconnected_P ?$P :P

Rob

Edited December 16, 2008 by rob

[rdg]

vector $myP = $isconnected_P  ? $P : P;
vector $myN = $isconnected_N  ? $N : normalize(frontface(N, I));

This is a snippet of inner code from a vop and I just wanted clarification of what it means

vector $position = $P; I would use this normally

vector $position  = $isconnected_P ?$P :P;

I am not sure about this and why its even needed as if P , N are not connected its hardley going to work

$isconnected_P ?$P :P

Rob

x = <boolean> ? <true> : <false>;

This is called a tertiary comparator (if think) and is a shorthand for if then else.

x gets the true expression assigned, if the boolean is true, else it gets the false expression.

in your sample it means:

If P is connected to the input of the node that generated this code, then use the value of this input, else use the global variable P.

Quite handy if you want to make your code able to use custom versions of global variables.

Also quite common when dealing with UVs, In this case you check if UVs are bound and switch to s and t if they aren't.

Hope this helps.

Georg

[rob]

That really does help.! I better start using it !

Rob

[rdg]

Errata:

it's called: ternary operator