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#include <stdlib.h>
#include <math.h>
#include "wetpix.h"
#include "wetphysics.h"
#include "wetpaint.h"
/* This function is not entirely satisfactory - the compositing is basically
opaque, and it really should do wet compositing. */
void
wet_dab(WetLayer * layer,
WetPix * paint,
double x, double y, double r, double pressure, double strength)
{
double r_fringe;
int x0, y0;
int x1, y1;
WetPix *wet_line;
int xp, yp;
double xx, yy, rr;
double eff_height;
double press, contact;
WetPixDbl wet_tmp, wet_tmp2;
r_fringe = r + 1;
x0 = floor(x - r_fringe);
y0 = floor(y - r_fringe);
x1 = ceil(x + r_fringe);
y1 = ceil(y + r_fringe);
if (x0 < 0)
x0 = 0;
if (y0 < 0)
y0 = 0;
if (x1 >= layer->width)
x1 = layer->width;
if (y1 >= layer->height)
y1 = layer->height;
wet_line = layer->buf + y0 * layer->rowstride;
for (yp = y0; yp < y1; yp++) {
yy = (yp + 0.5 - y);
yy *= yy;
for (xp = x0; xp < x1; xp++) {
xx = (xp + 0.5 - x);
xx *= xx;
rr = yy + xx;
if (rr < r * r)
press = pressure * 0.25;
else
press = -1;
eff_height =
(wet_line[xp].h + wet_line[xp].w -
192) * (1.0 / 255);
contact = (press + eff_height) * 0.2;
if (contact > 0.5)
contact =
1 - 0.5 * exp(-2.0 * contact - 1);
if (contact > 0.0001) {
int v;
double rnd = rand() * (1.0 / RAND_MAX);
v = wet_line[xp].rd;
wet_line[xp].rd =
floor(v +
(paint->rd * strength -
v) * contact + rnd);
v = wet_line[xp].rw;
wet_line[xp].rw =
floor(v +
(paint->rw * strength -
v) * contact + rnd);
v = wet_line[xp].gd;
wet_line[xp].gd =
floor(v +
(paint->gd * strength -
v) * contact + rnd);
v = wet_line[xp].gw;
wet_line[xp].gw =
floor(v +
(paint->gw * strength -
v) * contact + rnd);
v = wet_line[xp].bd;
wet_line[xp].bd =
floor(v +
(paint->bd * strength -
v) * contact + rnd);
v = wet_line[xp].bw;
wet_line[xp].bw =
floor(v +
(paint->bw * strength -
v) * contact + rnd);
v = wet_line[xp].w;
wet_line[xp].w =
floor(v + (paint->w - v) * contact +
rnd);
}
}
wet_line += layer->rowstride;
}
}
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