double reg_calc_area_complex_polygon( regShape* shape ) {
regRegion *temp;
regShape *copy;
double area;
fprintf(stderr, "WARNING: Calculating area of a complex polygon ");
fprintf(stderr,"using brute force method. This may take a long time.\n");
// Create a new region with just the polygon
temp = regCreateRegion(NULL, NULL);
copy = shape->copy(shape);
// Analytic area calculations always computes the area of the interior
// of the shape.
copy->include = regInclude;
regAddShape(temp, regAND, copy);
// Calc the extent of the polygon then trim the bounds to fit within
// the original region if available
regCalcExtentPolygon(shape, temp->xregbounds, temp->yregbounds);
if (shape->region) {
reg_trim_extent(temp->xregbounds,
temp->yregbounds,
shape->region->xregbounds,
shape->region->yregbounds, 0);
}
area = regComputePixellatedArea(temp, temp->xregbounds, temp->yregbounds, 1);
// Free and return
regFree(temp);
return area;
}
// Computes the bounding rectangle corners of the region w.r.t. the field
// and places the coordinates into xpos and ypos. Returns 1 if the shape is
// completely contained within the field. 0 if the coordinates had to be
// trimmed.
int regExtent(regRegion * region,
double *fieldx,
double *fieldy,
double *xpos,
double *ypos)
{
regShape *atShape;
int retval = 1;
int start;
int cstart;
int state = 0;
// Shape extents
double sxpos[2];
double sypos[2];
// Component extents
double cxpos[2];
double cypos[2];
// The null region is taken to be the field
if (!region) {
xpos[0] = fieldx[0];
xpos[1] = fieldx[1];
ypos[0] = fieldy[0];
ypos[1] = fieldy[1];
return retval;
}
// Set arrays to 0 and start/cstart to 1
start = reg_zero_bounds(xpos, ypos);
cstart = reg_zero_bounds(cxpos, cypos);
atShape = region->shape;
while (atShape != NULL) {
do {
reg_extent_shape(atShape, fieldx, fieldy, sxpos, sypos);
reg_trim_extent(cxpos, cypos, sxpos, sypos, cstart);
state = 1;
cstart = 0;
if (atShape->next == NULL) {
state = 0;
}
else if (atShape->next->component != atShape->component) {
state = 0;
}
atShape = atShape->next;
} while (state);
/* End of component */
reg_union_extent(xpos, ypos, cxpos, cypos, start);
start = 0;
cstart = reg_zero_bounds(cxpos, cypos);
}
/* Trim to field */
retval = reg_trim_extent(xpos, ypos, fieldx, fieldy, 0);
return (retval);
}
