| rotate |
(Number angle) |
typedict.Matrix |
| |
Changes this matrix so that the coordinate axes are rotated by
angle
degrees in the direction that takes the positive x-axis into the
positive y-axis when
angle
is positive, which is often observed and as a clockwise rotation
when objects are drawn on your screen,
and returns this matrix to the caller.
The mathematical description of
rotate
says it transforms the point
(x, y)
into
(x*cos(angle) - y*sin(angle), x*sin(angle) + y*cos(angle))
which means the new and old matrices map
(1, 0)
and
(cos(angle), sin(angle))
into the same point.
| |
| Example: |
The program,
import yoix.*.*;
DrawXAxis(Graphics graphics) {
double axislength = 2.5*72;
double ticklength = 72/16;
double delta = axislength/10;
int n;
graphics { // "named block"
gsave();
moveto(0, 0);
lineto(axislength, 0);
moveto(delta, 0);
for (n = 0; n < 10; n++) {
rlineto(0, ticklength);
rmoveto(delta, -ticklength);
}
stroke();
grestore();
}
}
DrawAxes(Graphics graphics) {
graphics { // "named block"
gsave();
DrawXAxis(graphics);
rotate(90); // prepare for y axis
scale(1, -1); // flipped for ticks
DrawXAxis(graphics);
grestore();
}
}
JFrame f = {
Color background = Color.white;
paint(Rectangle rect) {
graphics { // "named block"
gsave();
translate(72, 72);
setrgbcolor(1, 0, 0);
DrawAxes(graphics);
rotate(10);
setrgbcolor(0, 0, 1);
DrawAxes(graphics);
grestore();
}
}
};
f.visible = TRUE;
defines functions that can draw simple coordinate axes and then
defines a paint function in a frame that draws a set of axes in blue,
applies a small rotation, and draws the new set of axes in red.
| | |
| Return: |
Matrix
| | |
| See Also: |
concat,
concatmatrix,
currentmatrix,
dividematrix,
dtransform,
Graphics,
identmatrix,
idtransform,
initmatrix,
invertmatrix,
itransform,
maptopixel,
scale,
setmatrix,
shear,
transform,
translate
|
|
Yoix is a registered trademark of AT&T Inc.
|
