Why does a part of this code runs only once in VEX ?

[AntoineSfx]

Input is a line, I'm trying to set a different pscale attribute on the first and last point. In PointWrangle (Run over Points), I have this:
 

f@pscale=chf("scl") ;
float scale=chf("scl");
printf("begin %f\n",scale);
printf("numpt=%d\n", @numpt);
printf("ptnum=%d\n", @ptnum);

if (@ptnum==0 || @ptnum== @numpt-1)
f@pscale=chf("scl") ;
else f@pscale=1 ;

 

output:

(twice the same thing)

begin 0.101000
numpt=10
ptnum=0
ptnum=1
ptnum=2
ptnum=3
ptnum=4
ptnum=5
ptnum=6
ptnum=7
ptnum=8
ptnum=9
begin 0.101000
numpt=10
ptnum=0
ptnum=1
ptnum=2
ptnum=3
ptnum=4
ptnum=5
ptnum=6
ptnum=7
ptnum=8
ptnum=9

 

Is the compiler parallelizing portion of codes which refer to points attributes ?

Edited January 31, 2018 by AntoineSfx

[Atom]

I would construct the setup like this. In your IF statement it seems like you are "ORING zero with @ptnum. Use parenthesis to keep logic clear.

[AntoineSfx]

54 minutes ago, Atom said:

I would construct the setup like this. In your IF statement it seems like you are "ORING zero with @ptnum. Use parenthesis to keep logic clear.

Operators precedence is such that non contrived expressions don't require additional parenthesis.. Unless you want to assign the result of a comparison or something. It's built-in in the BNF.

However it doesn't explain why I have that behavior on the original code. 

[Noobini]

50 minutes ago, AntoineSfx said:

Operators precedence is such that non contrived expressions don't require additional parenthesis.. Unless you want to assign the result of a comparison or something. It's built-in in the BNF.

However it doesn't explain why I have that behavior on the original code. 

I found that if you drag the slider on your Scl param, it prints it twice.......but if you type in a number, press Enter...it does it ONCE as expected

(same as using the value ladder...prints it twice)

Edited January 31, 2018 by Noobini

[AntoineSfx]

3 minutes ago, Noobini said:

I found that if you drag the slider on your Scl param, it prints it twice.......but if you type in a number, press Enter...it does it ONCE as expected

(same as using the value ladder...prints it twice)

the real question is, why does

printf("numpt=%d\n", @numpt);

seems to be outside of the points loop, while

printf("ptnum=%d\n", @ptnum);

seems to be be inside the points loop. I assume some optimization is made on the program, but I can't find exactly what. I know that vcc (or should I say the VM running its output) runs several threads, but it's unclear what happens to the VEX I wrote in that box.

[acey195]

both are in the points loop, but if the thing printed is exactly the same (and the calculation/memory needed is exactly the same) it will only do the print once, as VEX optimizes these things.

[f1480187]

Point wrangle:

do a;
do b;
do c;

do a:
    on point 0
    on point 1
    on point 2

do b:
    on point 0
    on point 1
    on point 2

do c:
    on point 0
    on point 1
    on point 2

 

Detail wrangle point loop:

for (int i = 0; i < @numpt; i++)
{
    do a;
    do b;
    do c;
}

on point 0:
    do a
    do b
    do c

on point 1:
    do a
    do b
    do c

on point 2:
    do a
    do b
    do c

 

Since the scale and @numpt are uniform vars, print instruction was executed once and cached. @ptnum is varying and printf executed every time. It's an old issue with debugging VEX wrangles using printf().

Edited February 1, 2018 by f1480187

[acey195]

I would say its a feature :P...

whenever I use printf() without having a condition like: if(@ptnum == 0){printf("stuff");}
I kinda want to punch myself because of the millions of prints it wants to do..