# [Paraview] Creating Spatial Positions For Optimum Results In Paraview

Hi there,

I've had some great advice on here previously, however it isn't supplying the
correct results.

I've spoken to my lecturer and have done some digging myself, and the reason i
believe that the code (attached below) isn't providing a decent output to use
in Paraview is that it's missing spatial positioning. I know the equations to
do so, but i'm absolutely stuck on where to include them in the code: to find
the position of x is: i * dx / xMax. where i is the index of the current data
sample and xMax is 10. dx is the unit position between the data samples, so to
find this it will be number of data samples along x / xMax.V The same applies
for y. But just to reiterate, i have not the slightest idea on where or how to
implement this in my current set up.

Secondly, when using the output provided by the code, if to loo, it looks as if
all of the z slices are on top of one another. (To note, when compiling the
code in commandline, i use 64 64 64 1). Correct me if i'm wrong, but I believe
that the spatial positioning will rectify, or it could be the row id that
Paraview generates. (Side note, i'm using dot to points to just to get an idea
of the datas layout)

Thanks so much for the help in advance

#include<stdio.h>
#include<math.h>
#include<string.h>
#include<stdlib.h>

void gen_sally( int xs, int ys, int zs, int time, float *sally )
/*
*  Gen_Sally creates a vector field of dimension [xs,ys,zs,3] from
*  a proceedural function. By passing in different time arguements,
*  a slightly different and rotating field is created.
*
*  The magnitude of the vector field is highest at some funnel shape
*  and values range from 0.0 to around 0.4 (I think).
*
*  I just wrote these comments, 8 years after I wrote the function.
*
*  Developed by Sally of Sally University
*
*/
{
float x, y, z;
int ix, iy, iz;
float r, xc, yc, scale, temp, z0;
float r2 = 8;
float SMALL = 0.00000000001;
float xdelta = 1.0 / (xs-1.0);
float ydelta = 1.0 / (ys-1.0);
float zdelta = 1.0 / (zs-1.0);

for( iz = 0; iz < zs; iz++ )
{
z = iz * zdelta;                        // map z to 0->1
xc = 0.5 + 0.1*sin(0.04*time+10.0*z);   // For each z-slice, determine the
spiral circle.
yc = 0.5 + 0.1*cos(0.03*time+3.0*z);    //    (xc,yc) determine the center
of the circle.
r = 0.1 + 0.4 * z*z + 0.1 * z * sin(8.0*z); //  The radius also changes at
each z-slice.
r2 = 0.2 + 0.1*z;                           //    r is the center radius,
r2 is for damping
for( iy = 0; iy < ys; iy++ )
{
y = iy * ydelta;
for( ix = 0; ix < xs; ix++ )
{
x = ix * xdelta;
temp = sqrt( (y-yc)*(y-yc) + (x-xc)*(x-xc) );
scale = fabs( r - temp );
/*
*  I do not like this next line. It produces a discontinuity
*  in the magnitude. Fix it later.
*
*/
if ( scale > r2 )
scale = 0.8 - scale;
else
scale = 1.0;
z0 = 0.1 * (0.1 - temp*z );
if ( z0 < 0.0 )  z0 = 0.0;
temp = sqrt( temp*temp + z0*z0 );
scale = (r + r2 - temp) * scale / (temp + SMALL);
scale = scale / (1+z);
*sally++ = scale * (y-yc) + 0.1*(x-xc);
*sally++ = scale * -(x-xc) + 0.1*(y-yc);
*sally++ = scale * z0;
}
}
}
}

void create_csv(char* filename, float *sally, int size) {
printf("1\n Creating %s.csv file\n", filename);

FILE *fp;

fp = fopen(filename, "w");

fprintf(fp, "X,Y,Z\n");
int i;

for (i = 0; i < size; i++) {
fprintf(fp, "%f%c", sally[i], (i % 3) ? ',' : '\n');
}

fclose(fp);
printf("\n %sfile created", filename);
}

int main(int argc, char *argv[]){

printf("1\n");
int xs;
int ys;
int zs;
int time;
sscanf(argv[1],"%d",&xs);
sscanf(argv[2],"%d",&ys);
sscanf(argv[3],"%d",&zs);
sscanf(argv[4],"%d",&time);

int arraySize = xs*ys*zs*3;

//allocate memeory for array. This is done so that stack memory doesn't run
out.'
float* sally;
sally = (float*)malloc((arraySize) * sizeof(*sally));

//runs the code. One of the args is a pointer so no return type is needed.
gen_sally(xs,ys,zs,time,sally);

//create varibles for file generation
char filename[20] = "results.csv";
create_csv(filename, sally, arraySize);

free(sally);
return 0;
}
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