| pointInPolygon |
(Point p, Array xpoints, Array ypoints [, int count]) |
yoix.graphics |
| pointInPolygon |
(Point p, Number x0, Number y0, Number x1, Number y1, ...) |
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Returns
1
if
p
lies inside the polygon that has vertices at the points whose x and y coordinates
are supplied as numbers in the
xpoints
and
ypoints
arrays.
The number of vertices in the polygon can be specified by the optional
count
argument, which must be less than or equal to the number of elements in both
xpoints
and
ypoints.
When
count
is omitted
pointInPolygon
chooses a value that is the minimum of the size of the
xpoints
and
ypoints
arrays.
The Yoix implementation of
pointInPolygon
also accepts x and y coordinates of the vertices in the polygon as arguments.
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| Example: |
The program,
import yoix.*.*;
Star(double xcenter, double ycenter) {
return(
new Array {
xcenter + 0, ycenter + -50,
xcenter + 29, ycenter + 40,
xcenter + -47, ycenter + -15,
xcenter + 47, ycenter + -15,
xcenter + -29, ycenter + 40,
}
);
}
JFrame frame = {
Array layout = {
new JCanvas {
Color background = Color.black;
Graphics graphics = {
Color foreground = Color.yellow;
};
Array star;
paint(clip) {
this.star = Star(size.width - 72, size.height - 72*2);
fillPolygon(this, unroll(star));
}
mousePressed(e) {
int result;
if (star != NULL)
result = pointInPolygon(e.location, unroll(star));
puts(result ? "inside" : "outside");
}
},
};
};
frame.visible = TRUE;
sleep(5);
exit(0);
defines a paint function in a canvas that fills a yellow five pointed star
that is centered 1 inch from the right and 2 inches from the bottom of the
canvas.
The canvas also defines a
mousePressed
event handler that uses
pointInPolygon
to report whether the cursor was inside or outside the star when the button
was pressed.
The x and y coordinates of the star are returned in an array
by the function named
Star.
The polygon is filled and queried by unrolling those coordinates using the
unroll
built-in and handing them to the
fillPolygon
and
pointInPolygon
built-ins.
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| See Also: |
clearRect,
copyArea,
drawArc,
drawImage,
drawLine,
drawOval,
drawPolygon,
drawPolyline,
drawRect,
drawRoundRect,
drawString,
fillArc,
fillOval,
fillPolygon,
fillRect,
fillRoundRect,
pointInRect,
rectContainsRect,
rectIntersectionRect,
rectIntersectsRect,
rectUnionRect,
stringBounds,
stringWidth
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Yoix is a registered trademark of AT&T Inc.
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