gimp/plug-ins/ifscompose/ifscompose_utils.c

919 lines
22 KiB
C

/* The GIMP -- an image manipulation program
* Copyright (C) 1995 Spencer Kimball and Peter Mattis
*
* IfsCompose is a interface for creating IFS fractals by
* direct manipulation.
* Copyright (C) 1997 Owen Taylor
*
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <gdk/gdk.h>
#include <libgimp/gimp.h>
#include "ifscompose.h"
typedef struct {
GdkPoint point;
gdouble angle;
} SortPoint;
/* local functions */
static void
aff_element_compute_click_boundary(AffElement *elem, int num_elements,
gdouble *points_x, gdouble *points_y);
static guchar *
create_brush(IfsComposeVals *ifsvals, gint *brush_size, gdouble *brush_offset);
void
aff2_translate(Aff2 *naff, gdouble x, gdouble y)
{
naff->a11 = 1.0;
naff->a12 = 0;
naff->a21 = 0;
naff->a22 = 1.0;
naff->b1 = x;
naff->b2 = y;
}
void
aff2_rotate(Aff2 *naff, gdouble theta)
{
naff->a11 = cos(theta);
naff->a12 = sin(theta);
naff->a21 = -naff->a12;
naff->a22 = naff->a11;
naff->b1 = 0;
naff->b2 = 0;
}
void
aff2_scale(Aff2 *naff, gdouble s, gint flip)
{
if (flip)
naff->a11 = -s;
else
naff->a11 = s;
naff->a12 = 0;
naff->a21 = 0;
naff->a22 = s;
naff->b1 = 0;
naff->b2 = 0;
}
/* Create a unitary transform with given x-y asymmetry and shear */
void
aff2_distort(Aff2 *naff, gdouble asym, gdouble shear)
{
naff->a11 = asym;
naff->a22 = 1/asym;
naff->a12 = shear;
naff->a21 = 0;
naff->b1 = 0;
naff->b2 = 0;
}
/* Find a pure stretch in some directon that brings xo,yo to xn,yn */
void
aff2_compute_stretch(Aff2 *naff,
gdouble xo, gdouble yo,
gdouble xn, gdouble yn)
{
gdouble denom = xo*xn + yo*yn;
if (denom == 0.0) /* singular */
{
naff->a11 = 1.0;
naff->a12 = 0.0;
naff->a21 = 0.0;
naff->a22 = 1.0;
}
else
{
naff->a11 = (SQR(xn) + SQR(yo))/denom;
naff->a22 = (SQR(xo) + SQR(yn))/denom;
naff->a12 = naff->a21 = (xn*yn - xo*yo)/denom;
}
naff->b1 = 0.0;
naff->b2 = 0.0;
}
void
aff2_compose(Aff2 *naff, Aff2 *aff1, Aff2 *aff2)
{
naff->a11 = aff1->a11*aff2->a11 + aff1->a12*aff2->a21;
naff->a12 = aff1->a11*aff2->a12 + aff1->a12*aff2->a22;
naff->b1 = aff1->a11*aff2->b1 + aff1->a12*aff2->b2 + aff1->b1;
naff->a21 = aff1->a21*aff2->a11 + aff1->a22*aff2->a21;
naff->a22 = aff1->a21*aff2->a12 + aff1->a22*aff2->a22;
naff->b2 = aff1->a21*aff2->b1 + aff1->a22*aff2->b2 + aff1->b2;
}
/* Returns the identity matrix if the original matrix was singular */
void
aff2_invert(Aff2 *naff, Aff2 *aff)
{
gdouble det = aff->a11*aff->a22 - aff->a12*aff->a21;
if (det==0)
{
aff2_scale(naff,1.0,0);
}
else
{
naff->a11 = aff->a22 / det;
naff->a22 = aff->a11 / det;
naff->a21 = - aff->a21 / det;
naff->a12 = - aff->a12 / det;
naff->b1 = - naff->a11*aff->b1 - naff->a12*aff->b2;
naff->b2 = - naff->a21*aff->b1 - naff->a22*aff->b2;
}
}
void
aff2_apply(Aff2 *aff, gdouble x, gdouble y,
gdouble *xf, gdouble *yf)
{
gdouble xt = aff->a11*x + aff->a12*y + aff->b1;
gdouble yt = aff->a21*x + aff->a22*y + aff->b2;
*xf = xt;
*yf = yt;
}
/* Find the fixed point of an affine transformation
(Will return garbage for pure translations) */
void
aff2_fixed_point(Aff2 *aff, gdouble *xf, gdouble *yf)
{
Aff2 t1,t2;
t1.a11 = 1-aff->a11;
t1.a22 = 1-aff->a22;
t1.a12 = -aff->a12;
t1.a21 = -aff->a21;
t1.b1 = 0;
t1.b2 = 0;
aff2_invert(&t2,&t1);
aff2_apply(&t2,aff->b1,aff->b2,xf,yf);
}
void
aff3_apply (Aff3 *t, gdouble x, gdouble y, gdouble z,
gdouble *xf, gdouble *yf, gdouble *zf)
{
double xt = t->vals[0][0]*x + t->vals[0][1]*y + t->vals[0][2]*z + t->vals[0][3];
double yt = t->vals[1][0]*x + t->vals[1][1]*y + t->vals[1][2]*z + t->vals[1][3];
double zt = t->vals[2][0]*x + t->vals[2][1]*y + t->vals[2][2]*z + t->vals[2][3];
*xf = xt;
*yf = yt;
*zf = zt;
}
static int
ipolygon_sort_func(const void *a, const void *b)
{
if (((SortPoint *)a)->angle < ((SortPoint *)b)->angle)
return -1;
else if (((SortPoint *)a)->angle > ((SortPoint *)b)->angle)
return 1;
else
return 0;
}
/* Return a newly-allocated polygon which is the convex hull
of the given polygon.
Uses the Graham scan. see
http://www.cs.curtin.edu.au/units/cg201/notes/node77.html
for a description
*/
IPolygon *
ipolygon_convex_hull(IPolygon *poly)
{
gint num_new = poly->npoints;
GdkPoint *new_points = g_new(GdkPoint,num_new);
SortPoint *sort_points = g_new(SortPoint,num_new);
IPolygon *new_poly = g_new(IPolygon,1);
gint i,j;
gint x1,x2,y1,y2;
gint lowest;
GdkPoint lowest_pt;
new_poly->points = new_points;
if (num_new <= 3)
{
memcpy(new_points,poly->points,num_new*sizeof(GdkPoint));
new_poly->npoints = num_new;
return new_poly;
}
/* scan for the lowest point */
lowest_pt = poly->points[0];
lowest = 0;
for (i=1;i<num_new;i++)
if (poly->points[i].y < lowest_pt.y)
{
lowest_pt = poly->points[i];
lowest = i;
}
/* sort by angle from lowest point */
for (i=0,j=0;i<num_new;i++,j++)
{
if (i==lowest)
j--;
else
{
gdouble dy = poly->points[i].y - lowest_pt.y;
gdouble dx = poly->points[i].x - lowest_pt.x;
if (dy==0 && dx==0)
{
j--;
num_new--;
continue;
}
sort_points[j].point = poly->points[i];
sort_points[j].angle = atan2(dy,dx);
}
}
qsort(sort_points,num_new-1,sizeof(SortPoint),ipolygon_sort_func);
/* now ensure that all turns as we trace the perimiter are
counter-clockwise */
new_points[0] = lowest_pt;
new_points[1] = sort_points[0].point;
x1 = new_points[1].x - new_points[0].x;
y1 = new_points[1].y - new_points[0].y;
for (i=1,j=2;j<num_new;i++,j++)
{
x2 = sort_points[i].point.x - new_points[j-1].x;
y2 = sort_points[i].point.y - new_points[j-1].y;
if (x2==0 && y2==0)
{
num_new--;
j--;
continue;
}
while (x1*y2 - x2*y1 < 0) /* clockwise rotation */
{
num_new--;
j--;
x1 = new_points[j-1].x - new_points[j-2].x;
y1 = new_points[j-1].y - new_points[j-2].y;
x2 = sort_points[i].point.x - new_points[j-1].x;
y2 = sort_points[i].point.y - new_points[j-1].y;
}
new_points[j] = sort_points[i].point;
x1 = x2;
y1 = y2;
}
g_free(sort_points);
new_poly->npoints = num_new;
return new_poly;
}
/* Determines whether a specified point is in the given polygon.
Based on
inpoly.c by Bob Stein and Craig Yap.
(Linux Journal, Issue 35 (March 1997), p 68)
*/
gint
ipolygon_contains(IPolygon *poly, gint xt, gint yt)
{
gint xnew, ynew;
gint xold, yold;
gint x1,y1;
gint x2,y2;
gint i;
gint inside = 0;
if (poly->npoints < 3)
return 0;
xold=poly->points[poly->npoints-1].x;
yold=poly->points[poly->npoints-1].y;
for (i=0;i<poly->npoints;i++)
{
xnew = poly->points[i].x;
ynew = poly->points[i].y;
if (xnew > xold)
{
x1 = xold;
x2 = xnew;
y1 = yold;
y2 = ynew;
}
else
{
x1 = xnew;
x2 = xold;
y1 = ynew;
y2 = yold;
}
if ((xnew < xt) == (xt <= xold) &&
(yt - y1)*(x2 - x1) < (y2 - y1)*(xt - x1))
inside = !inside;
xold = xnew;
yold = ynew;
}
return inside;
}
void
aff_element_compute_color_trans(AffElement *elem)
{
int i,j;
if (elem->v.simple_color)
{
gdouble mag2 = 0;
for (i=0;i<3;i++)
mag2 += SQR(elem->v.target_color.vals[i]);
/* For mag2 == 0, the transformation blows up in general
but is well defined for hue_scale == value_scale, so
we assume that special case. */
if (mag2 == 0)
for (i=0;i<3;i++)
{
for (j=0;j<4;j++)
elem->color_trans.vals[i][j] = 0.0;
elem->color_trans.vals[i][i] = elem->v.hue_scale;
}
else
for (i=0;i<3;i++)
{
for (j=0;j<3;j++)
{
elem->color_trans.vals[i][j] = elem->v.target_color.vals[i]
/ mag2 * (elem->v.value_scale - elem->v.hue_scale);
if (i==j)
elem->color_trans.vals[i][j] += elem->v.hue_scale;
}
elem->color_trans.vals[i][3] =
(1-elem->v.value_scale)*elem->v.target_color.vals[i];
}
aff3_apply(&elem->color_trans,1.0,0.0,0.0,&elem->v.red_color.vals[0],
&elem->v.red_color.vals[1],&elem->v.red_color.vals[2]);
aff3_apply(&elem->color_trans,0.0,1.0,0.0,&elem->v.green_color.vals[0],
&elem->v.green_color.vals[1],&elem->v.green_color.vals[2]);
aff3_apply(&elem->color_trans,0.0,0.0,1.0,&elem->v.blue_color.vals[0],
&elem->v.blue_color.vals[1],&elem->v.blue_color.vals[2]);
aff3_apply(&elem->color_trans,0.0,0.0,0.0,&elem->v.black_color.vals[0],
&elem->v.black_color.vals[1],&elem->v.black_color.vals[2]);
}
else
{
for (i=0;i<3;i++)
elem->color_trans.vals[i][0] = elem->v.red_color.vals[i]
- elem->v.black_color.vals[i];
for (i=0;i<3;i++)
elem->color_trans.vals[i][1] = elem->v.green_color.vals[i]
- elem->v.black_color.vals[i];
for (i=0;i<3;i++)
elem->color_trans.vals[i][2] = elem->v.blue_color.vals[i]
- elem->v.black_color.vals[i];
for (i=0;i<3;i++)
elem->color_trans.vals[i][3] = elem->v.black_color.vals[i];
}
}
void
aff_element_compute_trans(AffElement *elem, gdouble width, gdouble height,
gdouble center_x, gdouble center_y)
{
Aff2 t1, t2, t3;
/* create the rotation, scaling and shearing part of the transform */
aff2_distort(&t1, elem->v.asym, elem->v.shear);
aff2_scale(&t2, elem->v.scale, elem->v.flip);
aff2_compose(&t3, &t2, &t1);
aff2_rotate(&t2, elem->v.theta);
aff2_compose(&t1, &t2, &t3);
/* now create the translational part */
aff2_translate(&t2, -center_x*width, -center_y*width);
aff2_compose(&t3, &t1, &t2);
aff2_translate(&t2, elem->v.x*width, elem->v.y*width);
aff2_compose(&elem->trans, &t2, &t3);
}
void
aff_element_decompose_trans(AffElement *elem, Aff2 *aff, gdouble width,
gdouble height, gdouble center_x,
gdouble center_y)
{
Aff2 t1,t2;
gdouble det,scale,sign;
/* pull of the translational parts */
aff2_translate(&t1,center_x*width,center_y*width);
aff2_compose(&t2,aff,&t1);
elem->v.x = t2.b1 / width;
elem->v.y = t2.b2 / width;
det = t2.a11*t2.a22 - t2.a12*t2.a21;
if (det == 0.0)
{
elem->v.scale = 0.0;
elem->v.theta = 0.0;
elem->v.asym = 1.0;
elem->v.shear = 0.0;
elem->v.flip = 0;
}
else
{
if (det >= 0)
{
scale = elem->v.scale = sqrt(det);
sign = 1;
elem->v.flip = 0;
}
else
{
scale = elem->v.scale = sqrt(-det);
sign = -1;
elem->v.flip = 1;
}
elem->v.theta = atan2(-t2.a21,t2.a11);
if (cos(elem->v.theta) == 0.0)
{
elem->v.asym = - t2.a21 / scale / sin(elem->v.theta);
elem->v.shear = - sign * t2.a22 / scale / sin(elem->v.theta);
}
else
{
elem->v.asym = sign * t2.a11 / scale / cos(elem->v.theta);
elem->v.shear = sign *
(t2.a12/scale - sin(elem->v.theta)/elem->v.asym)
/ cos(elem->v.theta);
}
}
}
static void
aff_element_compute_click_boundary(AffElement *elem, int num_elements,
gdouble *points_x, gdouble *points_y)
{
gint i;
gdouble xtot = 0;
gdouble ytot = 0;
gdouble xc, yc;
gdouble theta;
gdouble sth,cth; /* sin(theta), cos(theta) */
gdouble axis1,axis2;
gdouble axis1max, axis2max, axis1min, axis2min;
/* compute the center of mass of the points */
for (i=0; i<num_elements; i++)
{
xtot += points_x[i];
ytot += points_y[i];
}
xc = xtot/num_elements;
yc = ytot/num_elements;
/* compute the sum of the (x+iy)^2, and take half the the resulting
angle (xtot+iytot = A*exp(2i*theta)), to get an average direction */
xtot = 0;
ytot = 0;
for (i=0; i<num_elements; i++)
{
xtot += SQR(points_x[i]-xc)-SQR(points_y[i]-yc);
ytot += 2*(points_x[i]-xc)*(points_y[i]-yc);
}
theta = 0.5*atan2(ytot,xtot);
sth = sin(theta);
cth = cos(theta);
/* compute the minimum rectangle at angle theta that bounds the points,
1/2 side lenghs left in axis1, axis2, center in xc, yc */
axis1max = axis1min = 0.0;
axis2max = axis2min = 0.0;
for (i=0; i<num_elements; i++)
{
gdouble proj1 = (points_x[i]-xc)*cth + (points_y[i]-yc)*sth;
gdouble proj2 = -(points_x[i]-xc)*sth + (points_y[i]-yc)*cth;
if (proj1 < axis1min)
axis1min = proj1;
if (proj1 > axis1max)
axis1max = proj1;
if (proj2 < axis2min)
axis2min = proj2;
if (proj2 > axis2max)
axis2max = proj2;
}
axis1 = 0.5*(axis1max - axis1min);
axis2 = 0.5*(axis2max - axis2min);
xc += 0.5*((axis1max + axis1min)*cth - (axis2max+axis2min)*sth);
yc += 0.5*((axis1max + axis1min)*sth + (axis2max+axis2min)*cth);
/* if the the rectangle is less than 10 pixels in any dimension,
make it click_boundary, otherwise set click_boundary = draw_boundary */
if (axis1 < 8.0 || axis2 < 8.0)
{
GdkPoint *points = g_new(GdkPoint,4);
elem->click_boundary = g_new(IPolygon,1);
elem->click_boundary->points = points;
elem->click_boundary->npoints = 4;
if (axis1 < 8.0) axis1 = 8.0;
if (axis2 < 8.0) axis2 = 8.0;
points[0].x = xc + axis1*cth - axis2*sth;
points[0].y = yc + axis1*sth + axis2*cth;
points[1].x = xc - axis1*cth - axis2*sth;
points[1].y = yc - axis1*sth + axis2*cth;
points[2].x = xc - axis1*cth + axis2*sth;
points[2].y = yc - axis1*sth - axis2*cth;
points[3].x = xc + axis1*cth + axis2*sth;
points[3].y = yc + axis1*sth - axis2*cth;
}
else
elem->click_boundary = elem->draw_boundary;
}
void
aff_element_compute_boundary(AffElement *elem, gint width,
gint height,
AffElement **elements,
int num_elements)
{
int i;
IPolygon tmp_poly;
gdouble *points_x;
gdouble *points_y;
if (elem->click_boundary && elem->click_boundary != elem->draw_boundary)
g_free(elem->click_boundary);
if (elem->draw_boundary)
g_free(elem->draw_boundary);
tmp_poly.npoints = num_elements;
tmp_poly.points = g_new(GdkPoint,num_elements);
points_x = g_new(gdouble,num_elements);
points_y = g_new(gdouble,num_elements);
for (i=0;i<num_elements;i++)
{
aff2_apply(&elem->trans,elements[i]->v.x*width,elements[i]->v.y*width,
&points_x[i],&points_y[i]);
tmp_poly.points[i].x = (gint)points_x[i];
tmp_poly.points[i].y = (gint)points_y[i];
}
elem->draw_boundary = ipolygon_convex_hull(&tmp_poly);
aff_element_compute_click_boundary(elem,num_elements,points_x,points_y);
g_free(tmp_poly.points);
}
void
aff_element_draw(AffElement *elem, gint selected,
gint width, gint height,
GdkDrawable *win,
GdkGC *normal_gc,GdkGC *selected_gc,
GdkFont *font)
{
GdkGC *gc;
gint string_width = gdk_string_width (font,elem->name);
gint string_height = font->ascent + font->descent + 2;
if (selected)
gc = selected_gc;
else
gc = normal_gc;
gdk_draw_string(win,font,gc,
elem->v.x*width-string_width/2,
elem->v.y*width+string_height/2,elem->name);
if (elem->click_boundary != elem->draw_boundary)
gdk_draw_polygon(win,normal_gc,FALSE,elem->click_boundary->points,
elem->click_boundary->npoints);
gdk_draw_polygon(win,gc,FALSE,elem->draw_boundary->points,
elem->draw_boundary->npoints);
}
AffElement *
aff_element_new(gdouble x, gdouble y, IfsColor color, gint count)
{
AffElement *elem = g_new(AffElement, 1);
char buffer[16];
elem->v.x = x;
elem->v.y = y;
elem->v.theta = 0.0;
elem->v.scale = 0.5;
elem->v.asym = 1.0;
elem->v.shear = 0.0;
elem->v.flip = 0;
elem->v.red_color = color;
elem->v.blue_color = color;
elem->v.green_color = color;
elem->v.black_color = color;
elem->v.target_color = color;
elem->v.hue_scale = 0.5;
elem->v.value_scale = 0.5;
elem->v.simple_color = TRUE;
elem->draw_boundary = NULL;
elem->click_boundary = NULL;
aff_element_compute_color_trans(elem);
elem->v.prob = 1.0;
sprintf(buffer,"%d",count);
elem->name = g_strdup(buffer);
return elem;
}
void
aff_element_free(AffElement *elem)
{
if (elem->click_boundary != elem->draw_boundary)
g_free(elem->click_boundary);
g_free(elem->draw_boundary);
g_free(elem);
}
#ifdef DEBUG_BRUSH
static brush_chars[] = {' ',':','*','@'};
#endif
static guchar *
create_brush(IfsComposeVals *ifsvals, gint *brush_size, gdouble *brush_offset)
{
gint i,j;
gint ii,jj;
guchar *brush;
#ifdef DEBUG_BRUSH
gdouble totpix = 0.0;
#endif
gdouble radius = ifsvals->radius * ifsvals->subdivide;
*brush_size = ceil(2*radius);
*brush_offset = 0.5 * (*brush_size-1);
brush = g_new(guchar,SQR(*brush_size));
for (i=0;i<*brush_size;i++)
{
for (j=0;j<*brush_size;j++)
{
gdouble d = sqrt(SQR(i-*brush_offset)+SQR(j-*brush_offset));
gdouble pixel = 0.0;
if (d-0.5*sqrt(2) > radius)
pixel = 0.0;
else if (d+0.5*sqrt(2) < radius)
pixel = 1.0;
else
for (ii=0;ii<10;ii++)
for (jj=0;jj<10;jj++)
{
d = sqrt(SQR(i-*brush_offset+ii*0.1-0.45)
+SQR(j-*brush_offset+jj*0.1-0.45));
pixel += (d<radius)/100.0;
}
brush[i**brush_size+j] = 255.999*pixel;
#ifdef DEBUG_BRUSH
putchar(brush_chars[(int)(pixel*3.999)]);
totpix += pixel;
#endif /* DEBUG_BRUSH */
}
#ifdef DEBUG_BRUSH
putchar('\n');
#endif /* DEBUG_BRUSH */
}
#ifdef DEBUG_BRUSH
printf("Brush total / area = %f\n",totpix/SQR(ifsvals->subdivide));
#endif /* DEBUG_BRUSH */
return brush;
}
void
ifs_render(AffElement **elements, gint num_elements,
gint width, gint height, gint nsteps,
IfsComposeVals *vals, gint band_y, gint band_height,
guchar *data, guchar *mask, guchar *nhits, gint preview)
{
gint i,k;
gdouble x,y;
gdouble r,g,b;
gint ri,gi,bi;
gint p0,psum;
gdouble pt;
guchar *ptr;
gint *prob;
gdouble *fprob;
gint subdivide;
guchar *brush = NULL;
gint brush_size;
gdouble brush_offset;
if (preview)
subdivide = 1;
else
subdivide = vals->subdivide;
/* compute the probabilities and transforms */
fprob = g_new(gdouble,num_elements);
prob = g_new(gint,num_elements);
pt = 0.0;
for (i=0;i<num_elements;i++)
{
aff_element_compute_trans(elements[i],width*subdivide,height*subdivide,
vals->center_x, vals->center_y);
fprob[i] = fabs(
elements[i]->trans.a11 * elements[i]->trans.a22
- elements[i]->trans.a12 * elements[i]->trans.a21);
/* As a heuristic, if the determinant is really small, it's
probably a line element, so increase the probability so
it gets rendered */
/* FIXME: figure out what 0.01 really should be */
if (fprob[i] < 0.01) fprob[i] = 0.01;
fprob[i] *= elements[i]->v.prob;
pt += fprob[i];
}
psum = 0;
for (i=0;i<num_elements;i++)
{
psum += G_MAXRAND * (fprob[i]/pt);
prob[i] = psum;
}
prob[i-1] = G_MAXRAND; /* make sure we don't get bitten
by roundoff*/
/* create the brush */
if (!preview)
brush = create_brush(vals,&brush_size,&brush_offset);
x = y = 0;
r = g = b = 0;
/* now run the iteration */
for (i=0;i<nsteps;i++)
{
if (!preview && !(i % 5000))
gimp_progress_update ((gdouble) i / (gdouble) nsteps);
p0 = rand();
k=0;
while (p0 > prob[k])
k++;
aff2_apply(&elements[k]->trans,x,y,&x,&y);
aff3_apply(&elements[k]->color_trans,r,g,b,&r,&g,&b);
if (i<50) continue;
ri= (gint)(255.999*r);
gi = (gint)(255.999*g);
bi = (gint)(255.999*b);
if (preview)
{
if ((x<width) && (y<(band_y+band_height)) &&
(x >= 0) && (y >= band_y) &&
(ri >= 0) && (ri < 256) &&
(gi >= 0) && (gi < 256) &&
(bi >= 0) && (bi < 256))
{
ptr = data + 3 * (((gint)(y-band_y))*width + (gint)x);
*ptr++ = ri;
*ptr++ = gi;
*ptr = bi;
}
}
else
if ((ri >= 0) && (ri < 256) &&
(gi >= 0) && (gi < 256) &&
(bi >= 0) && (bi < 256))
{
guint m_old;
guint m_new;
guint m_pix;
guint n_hits;
guint old_scale;
guint pix_scale;
gint index;
gint ii,jj;
gint jj0 = floor(y-brush_offset-band_y*subdivide);
gint ii0 = floor(x-brush_offset);
gint jjmax,iimax;
gint jjmin = 0;
gint iimin = 0;
if (ii0 < 0)
iimin = - ii0;
else
iimin = 0;
if (jj0 < 0)
jjmin = - jj0;
else
jjmin = 0;
if (jj0+brush_size >= subdivide*band_height)
jjmax = subdivide*band_height - jj0;
else
jjmax = brush_size;
if (ii0+brush_size >= subdivide*width)
iimax = subdivide*width - ii0;
else
iimax = brush_size;
for (jj=jjmin;jj<jjmax;jj++)
for (ii=iimin;ii<iimax;ii++)
{
index = (jj0+jj)*width*subdivide + ii0 + ii;
n_hits = nhits[index];
if (n_hits == 255)
continue;
m_pix = brush[jj*brush_size+ii];
if (!m_pix)
continue;
nhits[index] = ++n_hits;
m_old = mask[index];
m_new = m_old + m_pix - m_old*m_pix/255;
mask[index] = m_new;
/* relative probability that old colored pixel is on top */
old_scale = m_old*(255*n_hits-m_pix);
/* relative probability that new colored pixel is on top */
pix_scale = m_pix*((255-m_old)*n_hits+m_old);
ptr = data + 3*index;
*ptr = ( old_scale * (*ptr) + pix_scale * ri ) /
( old_scale + pix_scale );
ptr++;
*ptr = ( old_scale * (*ptr) + pix_scale * gi ) /
( old_scale + pix_scale );
ptr++;
*ptr = ( old_scale * (*ptr) + pix_scale * bi ) /
( old_scale + pix_scale );
}
}
} /* main iteration */
if (brush)
g_free(brush);
g_free(prob);
g_free(fprob);
}