noise using VEX and for loop

[bhaveshpandey]

I'm trying to write a VEX script which would apply noise to a geometry using a for loop..(I'm a newbie in VEX so please excuse my lack of knowledge )

basically what I intend to do is to Layer the noise affecting a geometry using its Point numbers as counters in the FOR loop and multiplying it with a Amplitude gain and Frequency gain parameter so that its increasing/decreasing for every iteration (which would thus give me good layer of noise applied on top of each other to a geometry.

here's the scrip so far:

float amp, freq, again, fgain, sum; 
int i;
for(i=0; i<npts; i++)
	{
		float noise;
		float AMP;
		float FREQ;
		float AMP= amp*again;
		float FREQ=freq*fgain;
		noise= AMP* noise(FREQ*P);
		sum+= noise;
	}


Sop
Sop1(amp=0.5, freq=2, again=o.5, fgain=0.5)
{
sum;
}

I have declared the variables etc..but i'm getting a syntax error in the first line..but I cant see anything wrong with it??

Also I'm not sure of how to execute it in the sop level...so just to check I just called it in the SOP level..but I'm not really sure about it....

could someone help me with this..

Thanks.

PS: here's a .vfl file

Edited September 10, 2009 by bhaveshpandey

[peliosis]

There are quite a few things wrong with your vex code.

Try this:

//pragmas for your parameters

#pragma hint again hidden
#pragma hint fgain hidden

//if you like to use some custom functions put them here


//the very body of the sop

Sop
Sop1(float amp=0.5, freq=2, again=0.5, fgain=0.5;) // your user parameters.
{

vector PP; //temporary P
float mynoise=0, sum=0;         
int i;

for(i=0; i<Npt; i++)
        {  
        mynoise= amp* noise(freq*P);
        sum = mynoise;
        }

PP = set(P.x, P.y+sum, P.z);
//do something to attributes to see the result:)
P = PP;                           
}

Have a look at houdini help, it's very good.

Edited September 10, 2009 by peliosis

[pencha]

check the Octaves param, it's available on most pre-built noises and I think it's exactly what you are trying to get.

[bhaveshpandey]

@Peliosis thanks a ton mate!! i see now where I was going off..

Yep Pencha I was trying to get that done but since I started learning VEX, I thought its better to try and implement it somewhere..I have a long road ahead I guess