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#include <math.h>
#include "image.h"
typedef double (* function_t) (double x);
#define SCALE 32.0
typedef struct
{
double r, g, b;
} color_t;
static void
plot (complex_image_t *image, color_t color, function_t f)
{
int i;
double max, min;
int first = 1;
double a, b;
for (i = 0; i < image->width; ++i)
{
double v = f(i / SCALE);
if (first || v < min)
min = v;
if (first || v > max)
max = v;
first = 0;
}
if (max - min < DBL_EPSILON)
return;
max = 2;
min = -2;
printf ("min %f max %f\n", min, max);
a = (image->height - 1) / (max - min);
b = - (min * (image->height - 1)) / (max - min);
for (i = 0; i < image->width; ++i)
{
double v = f (i / SCALE);
int idx;
complex_t p;
v = a * v + b;
printf ("scaled: %f\n", v);
idx = v + 0.5;
if (idx > image->height - 1)
idx = image->height - 1;
if (idx < 0)
idx = 0;
idx = idx * image->width + i;
p.re = 0;
p.im = 0;
image->red[idx] = image->green[idx] = image->blue[idx] = p;
image->red[idx].re = color.r;
image->green[idx].re = color.g;
image->blue[idx].re = color.b;
}
}
static const color_t red =
{
1.0, 0.0, 0.0
};
static const color_t blue =
{
0.4, 0.4, 1.0
};
static const color_t green =
{
0.0, 1.0, 0.0
};
static const color_t yellow =
{
1.0, 1.0, 0.0
};
#define HIGH (2)
#define ALIAS (1)
static double
orig (double x)
{
double v = (0.4 * sin (HIGH * x) + sin (0.3 * x));
return v;
}
static double
antialiased (double x)
{
double v = sin (0.3 * x);
return v;
}
static double
imperfect (double x)
{
return sin (0.3 * x) + 0.1 * sin (ALIAS * x);
}
static double
aliased (double x)
{
return sin (0.3 * x) + 0.4 * sin (ALIAS * x);
}
int
main ()
{
complex_image_t *image = complex_image_new (1024, 256);
plot (image, red, orig);
plot (image, blue, antialiased);
plot (image, green, aliased);
plot (image, yellow, imperfect);
complex_image_show ("func", image, CONVERT_RE);
}
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