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/**********************************************************/
/* Investigate Graphics GEMS transfer curve function parameters */
/**********************************************************/
/* Author: Graeme Gill
* Date: 2003/12/1
*
* Copyright 2003 Graeme W. Gill
*
* This material is licenced under the GNU AFFERO GENERAL PUBLIC LICENSE Version 3 :-
* see the License.txt file for licencing details.
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <numlib.h>
#include "plot.h"
#include "ui.h"
void usage(void);
#define XRES 100 /* Plot resolution */
/* Per transfer function */
static double tfunc(
double *v, /* Pointer to first parameter */
int luord, /* Curve order n..MPP_MXTCORD */
double vv /* Source of value */
) {
double g;
int ord;
if (vv < 0.0)
vv = 0.0;
else if (vv > 1.0)
vv = 1.0;
/* Process all the shaper orders from high to low. */
/* [These shapers were inspired by a Graphics Gem idea */
/* (Gems IV, VI.3, "Fast Alternatives to Perlin's Bias and */
/* Gain Functions, pp 401). */
/* They have the nice properties that they are smooth, and */
/* can't be non-monotonic. The control parameter has been */
/* altered to have a range from -oo to +oo rather than 0.0 to 1.0 */
/* so that the search space is less non-linear. ] */
for (ord = luord-1; ord >= 0; ord--) {
int nsec; /* Number of sections */
double sec; /* Section */
g = v[ord]; /* Parameter */
// nsec = 1 << ord; /* Double sections for each order */
nsec = ord + 1; /* Sections for each order */
vv *= (double)nsec;
sec = floor(vv);
if (((int)sec) & 1)
g = -g; /* Alternate action in each section */
vv -= sec;
if (g >= 0.0) {
vv = vv/(g - g * vv + 1.0);
} else {
vv = (vv - g * vv)/(1.0 - g * vv);
}
vv += sec;
vv /= (double)nsec;
}
return vv;
}
#define MAX_PARM 10
int
main(int argc, char *argv[]) {
int fa,nfa; /* argument we're looking at */
int np = 0; /* Current number of input parameters */
double params[MAX_PARM] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
int i;
double x;
double xx[XRES];
double y1[XRES];
error_program = "cv";
/* Process the arguments */
for(fa = 1;fa < argc;fa++) {
nfa = fa; /* skip to nfa if next argument is used */
if (np >= MAX_PARM)
break;
params[np++] = atof(argv[fa]);
}
if (np == 0)
np = 1;
printf("There are %d parameters:\n",np); fflush(stdout);
for (i = 0; i < np; i++) {
printf("Paramter %d = %f\n",i, params[i]); fflush(stdout);
}
/* Display the result */
for (i = 0; i < XRES; i++) {
x = i/(double)(XRES-1);
xx[i] = x;
y1[i] = tfunc(params, np, x);
if (y1[i] < -0.2)
y1[i] = -0.2;
else if (y1[i] > 1.2)
y1[i] = 1.2;
}
do_plot(xx,y1,NULL,NULL,XRES);
return 0;
}
/******************************************************************/
/* Error/debug output routines */
/******************************************************************/
void
usage(void) {
puts("usage: cv param0 [param1] [param2] ... ");
exit(1);
}
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