You can use SIN & COS to create/draw circles.
Please beware that the circle's center is also your base point (0,0). So without specifying an offset, some coordinates will be negative.
<?php
$circleRadius = 70;
$offsetX = 100;
$offsetY = 100;
for($i = 0; $i <= 360; ++$i) {
$x = round(cos($i * M_PI / 180) * $circleRadius);
$y = round(sin($i * M_PI / 180) * $circleRadius);
// Draw some pixel, or do something else here.
imagesetpixel($GDimage, $x + $offsetX, $y + $offsetY, $GDcolor);
}
?>
sin
(PHP 4, PHP 5, PHP 7, PHP 8)
sin — Sine
Description
sin() returns the sine of the num
parameter. The num parameter is in radians.
Parameters
-
num -
A value in radians
Return Values
The sine of num
Examples
Example #1 sin() example
<?php
// Precision depends on your precision directive
echo sin(deg2rad(60)); // 0.866025403 ...
echo sin(60); // -0.304810621 ...
?>
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gerjoo at gmail dot com ¶
14 years ago
