double noise1(int x)
{
int iterations, invpersistence, period_factor, smallest_period;
int i;
double y;
iterations = 8;
invpersistence = 2;
period_factor = 2;
smallest_period = 1;
y = 0;
for (i = 1; i <= iterations; i++) {
double c, period, x_anchor, v0, v1, v2, v3, x_transformed;
int x_i;
c = 1 / pow(invpersistence, i);
period = smallest_period * pow(period_factor, (iterations-i));
x_i = x / period;
x_anchor = x_i * period;
x_transformed = (x - x_anchor) / period;
v0 = nrand(x_i-1, 0, i);
v1 = nrand(x_i+0, 0, i);
v2 = nrand(x_i+1, 0, i);
v3 = nrand(x_i+2, 0, i);
y += c * interpolate_cubic(v0, v1, v2, v3, x_transformed);
}
y *= (invpersistence - 1);
return (y+1)/2;
}
void run ( float *buf, float *delaybuf, float delay, nframes_t nframes )
{
const nframes_t min_delay_samples = 4;
if ( delaybuf )
{
for (nframes_t i = 0; i < nframes; i++ )
{
float delay_samples = delaybuf[i] * _sample_rate;
if ( delay_samples > _buffer_mask + 1 )
delay_samples = _buffer_mask;
else if ( delay_samples < min_delay_samples )
delay_samples = min_delay_samples;
long idelay_samples = (long)delay_samples;
const float frac = delay_samples - idelay_samples;
const long read_index = _write_index - idelay_samples;
_buffer[_write_index++ & _buffer_mask] = buf[i];
const float read = interpolate_cubic (frac,
_buffer[(read_index-1) & _buffer_mask],
_buffer[read_index & _buffer_mask],
_buffer[(read_index+1) & _buffer_mask],
_buffer[(read_index+2) & _buffer_mask]);
buf[i] = read;
}
_samples_since_motion = 0;
}
else
{
float delay_samples = delay * _sample_rate;
if ( delay_samples > _buffer_mask + 1 )
delay_samples = _buffer_mask;
else if ( delay_samples < min_delay_samples )
delay_samples = min_delay_samples;
long idelay_samples = (long)delay_samples;
if ( _samples_since_motion >= _interpolation_delay_samples )
{
/* switch to non-interpolating mode */
for (nframes_t i = 0; i < nframes; i++ )
{
const long read_index = _write_index - idelay_samples;
_buffer[_write_index++ & _buffer_mask] = buf[i];
const float read = _buffer[read_index & _buffer_mask];
buf[i] = read;
}
}
else
{
/* linearly interpolate our way to an integer sample delay */
float frac = delay_samples - idelay_samples;
const float scale = 1.0f - (_samples_since_motion * _interpolation_delay_coeff);
for (nframes_t i = 0; i < nframes; i++ )
{
const long read_index = _write_index - idelay_samples;
_buffer[_write_index++ & _buffer_mask] = buf[i];
frac *= scale;
const float read = interpolate_cubic (frac,
_buffer[(read_index-1) & _buffer_mask],
_buffer[read_index & _buffer_mask],
_buffer[(read_index+1) & _buffer_mask],
_buffer[(read_index+2) & _buffer_mask]);
buf[i] = read;
}
_samples_since_motion += nframes;
}
}
}
static void process_file(FILE *fin, FILE *fout, char *infile, char *outfile) {
int r;
greymap_t *gm;
potrace_bitmap_t *bm;
void *sm;
int x, y;
int count;
for (count=0; ; count++) {
r = gm_read(fin, &gm);
switch (r) {
case -1: /* system error */
fprintf(stderr, "mkbitmap: %s: %s\n", infile, strerror(errno));
exit(2);
case -2: /* corrupt file format */
fprintf(stderr, "mkbitmap: %s: file format error: %s\n", infile, gm_read_error);
exit(2);
case -3: /* empty file */
if (count>0) { /* end of file */
return;
}
fprintf(stderr, "mkbitmap: %s: empty file\n", infile);
exit(2);
case -4: /* wrong magic */
if (count>0) {
fprintf(stderr, "mkbitmap: %s: warning: junk at end of file\n", infile);
return;
}
fprintf(stderr, "mkbitmap: %s: file format not recognized\n", infile);
fprintf(stderr, "Possible input file formats are: pnm (pbm, pgm, ppm), bmp.\n");
exit(2);
case 1: /* unexpected end of file */
fprintf(stderr, "mkbitmap: %s: warning: premature end of file\n", infile);
break;
}
if (info.invert) {
for (y=0; y<gm->h; y++) {
for (x=0; x<gm->w; x++) {
GM_UPUT(gm, x, y, 255-GM_UGET(gm, x, y));
}
}
}
if (info.highpass) {
r = highpass(gm, info.lambda);
if (r) {
fprintf(stderr, "mkbitmap: %s: %s\n", infile, strerror(errno));
exit(2);
}
}
if (info.lowpass) {
lowpass(gm, info.lambda1);
}
if (info.scale == 1 && info.bilevel) { /* no interpolation necessary */
sm = threshold(gm, info.level);
gm_free(gm);
} else if (info.scale == 1) {
sm = gm;
} else if (info.linear) { /* linear interpolation */
sm = interpolate_linear(gm, info.scale, info.bilevel, info.level);
gm_free(gm);
} else { /* cubic interpolation */
sm = interpolate_cubic(gm, info.scale, info.bilevel, info.level);
gm_free(gm);
}
if (!sm) {
fprintf(stderr, "mkbitmap: %s: %s\n", infile, strerror(errno));
exit(2);
}
if (info.bilevel) {
bm = (potrace_bitmap_t *)sm;
bm_writepbm(fout, bm);
bm_free(bm);
} else {
gm = (greymap_t *)sm;
gm_writepgm(fout, gm, NULL, 1, GM_MODE_POSITIVE, 1.0);
gm_free(gm);
}
}
}
