## approximating arcs using bezier curves -- how?

### approximating arcs using bezier curves -- how?

Some 2D graphics systems do not allow you to draw arcs. Instead they
want you to approximate the arcs using Bezier curves. An example is

Does anyone know the formula for doing this? I need to draw arbitrary
arcs (not just full circles).

### approximating arcs using bezier curves -- how?

> Some 2D graphics systems do not allow you to draw arcs. Instead they
> want you to approximate the arcs using Bezier curves. An example is
> Adobe's Portable Document Format (PDF).

> Does anyone know the formula for doing this? I need to draw arbitrary
> arcs (not just full circles).
> For arcs up to 90 degrees, from memory, I think you pick cubic

bezier endpoints p0, p3 to be the arc endpoints, and internal
points p1, p2 to satisfy:

* vectors p1-p0 and p2-p3 tangential at the arc endpoints
* |p1-p0| = |p2-p3|
* midpoint of the Bezier equals midpoint of the arc

For arc > 90 degrees, break it up into smaller arcs each no wider
than 90 degrees, and generate a bezier cubic for each one.

Hope this helps.

George Politis.

Can anyone provide me with algorithm for approximating elliptical arc
using
Bezier curves? If there is an algorithm already implemented, I prefer
if it is in "C" code.

I know that it is just an approximation and not exact, but this is
what I need.