Function:ns2svrl
From S2PLOT
ns2svrl
Change the volume rendering data and alpha channel ranges
Prototype
void ns2svrl(int vrid, float datamin, float datamax, float alphamin, float alphamax);
Description
Change the volume rendering data and alpha ranges. After changing, be sure to call ds2dvr with force=1. No protection is provided against datamin > datamax!
See Also
| ns2cvr | Create a volume rendering object |
| ds2dvr | Draw a volume render object from a dynamic callback |
Code Example
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <time.h>
#include "s2plot.h"
/* Global variables */
int vid; /* ID for volume render object */
float tr[12]; /* Transformation matrix */
float ***volume; /* The data cube */
int N = 5000; /* Number of data points */
float *x, *y, *z; /* Arrays for data values */
float gamin, gamax, gdmin, gdmax;
float ***initVolume(int nx, int ny, int nz)
/* Allocate memory and initialise a data cube */
{
float ***volume;
int i, j, k;
volume = (float ***)malloc(nx * sizeof(float **));
if (volume == NULL) {
fprintf(stderr,"Failed to allocate %ld bytes\n",nx*sizeof(float **));
exit(-1);
}
for (i=0;i<nx;i++) {
volume[i] = (float **)malloc(ny * sizeof(float *));
if (volume[i] == NULL) {
fprintf(stderr,"Failed to allocate %ld bytes\n",nx*sizeof(float *));
exit(-1);
}
for (j=0;j<ny;j++) {
volume[i][j] = (float *)malloc(nz * sizeof(float));
if (volume[i][j] == NULL) {
fprintf(stderr,"Failed to allocate %ld bytes\n",nx*sizeof(float));
exit(-1);
}
for (k=0;k<nz;k++) {
volume[i][j][k] = 0.0; /* Initialise */
}
}
}
return volume;
}
int mode = 0; /* Parameter changing mode for callback */
void ncb(int *N)
{
if (*N < 9) mode = *N;
}
void cb(double *t, int *kc)
/* A dynamic callback */
{
static int lkc = 0;
if (lkc != *kc) {
switch(mode) {
case 1 : gamin -= 0.1; /* Lower alpha min */
if (gamin < 0) gamin = 0.0;
break;
case 2 : gamin += 0.1; /* Raise alpha min */
if (gamin > gamax) gamin = gamax;
break;
case 3 : gamax -= 0.1; /* Lower alpha max */
if (gamax < gamin) gamax = gamin;
break;
case 4 : gamax += 0.1; /* Raise alpha max */
if (gamax > 1.0) gamax = 1.0;
break;
case 5 : gdmin -= 0.1; /* Lower data min */
if (gdmin < 0) gdmin = 0.0;
break;
case 6 : gdmin += 0.1; /* Raise data min */
if (gdmin > gdmax) gdmin = gdmax;
break;
case 7 : gdmax -= 0.1; /* Lower data max */
if (gdmax < gdmin) gdmax = gdmin;
break;
case 8 : gdmax += 0.1; /* Raise data max */
if (gdmax > 2.0) gdmax = 2.0;
break;
case 0 : gamin = 0.0; /* Reset */
gamax = 1.0;
gdmin = 0.0;
gdmax = 2.0;
break;
}
ns2svrl(vid, gdmin, gdmax, gamin, gamax);
/* Update the volume render data and alpha channel range */
}
ds2dvr(vid, 1); /* Draw the volume render object */
switch (mode) { /* Display a label */
case 0 : s2lab("","","","Reset - press space"); break;
case 1 : s2lab("","","","Lower alpha min - press space"); break;
case 2 : s2lab("","","","Raise alpha min - press space"); break;
case 3 : s2lab("","","","Lower alpha max - press space"); break;
case 4 : s2lab("","","","Raise alpha max - press space"); break;
case 5 : s2lab("","","","Lower data min - press space"); break;
case 6 : s2lab("","","","Raise data min - press space"); break;
case 7 : s2lab("","","","Lower data max - press space"); break;
case 8 : s2lab("","","","Raise data max - press space"); break;
}
lkc = *kc;
}
int main(int argc, char *argv[])
{
int i; /* Loop variable */
int nx = 32, ny = 32, nz = 32; /* Dimensions of data cube */
char trans; /* Transparency mode */
float x1 = -1.0, x2 = +1.0; /* Data range along axes */
float y1 = -1.0, y2 = +1.0;
float z1 = -1.0, z2 = +1.0;
int vi, vj, vk; /* Temporary variables */
float dx, dy, dz; /* Temporary variables */
COLOUR amb = {0.8, 0.8, 0.8}; /* Ambient light */
srand48((long)time(NULL)); /* Seed random numbers */
volume = initVolume(nx, ny, nz); /* Allocate memory */
for (i=0;i<12;i++) { /* Set-up transfrom matrix */
tr[i] = 0.0;
}
tr[ 0] = x1; /* Mapping from data cube */
tr[ 1] = (x2-x1)/(float)(nx-1.0); /* to physical coordinates */
tr[ 4] = y1;
tr[ 6] = (y2-y1)/(float)(ny-1.0);
tr[ 8] = z1;
tr[11] = (z2-z1)/(float)(nz-1.0);
gdmin = 0.0; /* Mininum data value in volume to plot */
gdmax = 2.0; /* Maximum data value in volume to plot */
gamin = 0.0; /* Minimum alpha channel value */
gamax = 0.8; /* Maximum alpha channel value */
trans = 't'; /* Transparency type */
dx = tr[1]*0.5; /* Offsets for window - voxels are pixel */
dy = tr[6]*0.5; /* centred */
dz = tr[11]*0.5;
s2opend("/S2MONO",argc,argv); /* Open the display */
s2swin(x1-dx,x2+dx, y1-dy,y2+dy, z1-dz,z2+dz); /* Set window coords */
s2box("BCDE",0,0,"BCDE",0,0,"BCDE",0,0); /* Draw coord box */
x = (float *)calloc(N, sizeof(float));
y = (float *)calloc(N, sizeof(float));
z = (float *)calloc(N, sizeof(float));
for (i=0;i<N;i++) { /* Create N random (x,y,z) values */
vi = (int)(drand48()*(nx));
vj = (int)(drand48()*(ny));
vk = (int)(drand48()*(nz));
x[i] = vi * tr[1] + tr[0];
y[i] = vj * tr[6] + tr[4];
z[i] = vk * tr[11] + tr[8];
volume[vi][vj][vk]+=1.0-drand48()*drand48();
/* Give a value to volume */
}
s2scir(1000,2000); /* Set colour range */
s2icm("mgreen",1000,2000); /* Install colour map */
vid = ns2cvr(volume, nx, ny, nz, 0, nx-1, 0, ny-1, 0, nz-1,
tr, trans, gdmin, gdmax, gamin, gamax);
/* Create the volume render object */
cs2scb(cb); /* Install a dynamic callback */
cs2sncb(ncb);
fprintf(stderr,"Press a number 1..8 to select mode\n");
fprintf(stderr,"Press <spacebar> to change level\n");
fprintf(stderr,"Press 0 and then <spacebar> to reset\n");
ss2srm(SHADE_FLAT); /* Set shading type to FLAT */
ss2sl(amb, 0, NULL, NULL, 0); /* Ambient lighting only */
s2show(1); /* Open the s2plot window */
return 1;
}
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