Last active
August 29, 2015 14:14
-
-
Save UnVoiding/a02600bdd3c5693c0c51 to your computer and use it in GitHub Desktop.
Canvas arc. Tangent from point to circle.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| function TangentToCircle(fromx, fromy, cx, cy, r) { | |
| var canvas = document.getElementById('canvas1'); | |
| var context = canvas.getContext('2d'); | |
| var fi = 0; | |
| context.beginPath(); | |
| if (fromx != cx && fromy != cy) { | |
| var length = Math.sqrt(Math.pow(fromx - cx, 2) + Math.pow(fromy - cy, 2)); | |
| var a = Math.atan(r/length); | |
| var g = Math.acos((cx - fromx)/length); | |
| fi = Math.PI/2 - g + a; | |
| context.moveTo(fromx, fromy); | |
| } | |
| context.arc(cx, cy, r, fi, 2*Math.PI + fi); | |
| context.stroke(); | |
| } |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment