在PHP中的两点之间绘制一条曲线

Question

I want to draw a simple curved line between two points. More specifically, the top left and bottom right corner of an image of arbitrary size.

I tried using imagearc, but apparently that's not what I'm looking for. To illustrate what I mean:

I can't find any function to help me along, so any help would be appreciated :)

Answer 1

I solved it using imagearc after all.

The trick is to set the bottom left corner as the center, -90° start angle, 0° end angle and double the size of the image:

//GET VARS
$width = $_GET['width'];
$height = $_GET['height'];

//CREATE IMGS
$image = imagecreatetruecolor($width, $height);
$color = imagecolorallocate($image, 255, 0, 0);

imagearc(    $image,
             0, 0, //center point = bottom-left corner
             $width*2, $height*2, //size = image size * 2
             -90, //top left
             0, //bottom right
             $color);


//OUTPUT IMAGE
header('Content-Type: image/png');
imagepng($image);

//DESTROY IMAGE
imagedestroy($image);

Looks like this: http://www.schizosplayground.com/pers/curvedlinetest.php?width=132&height=163