Re: [Gzz] Re: [Gzz-commits] gzz/doc/gl irreg0.png irreg1.png

[Tuomas Lukka]

On Wed, Sep 11, 2002 at 05:30:44PM +0200, Benja Fallenstein wrote:
> Tuomas Lukka wrote:
> 
> >On Wed, Sep 11, 2002 at 10:00:04AM +0200, Benja Fallenstein wrote:
> > 
> >
> >>Remember that the difficult part in these is how to draw the border 
> >>correctly (or so I think)-- any ideas on that, yet?
> >>
> >
> >Try "make runirregu" ;) ;) ;)
> > 
> >
> 
> Hm, are you saying that you've already implemented it? How?

A simple trick, which jvk suggested. (I had used it somewhere before
but had forgotten it in the meantime)

        First, draw the shape 4 times in black, shifted 2 pixels up,
        down, left, right respectively.

        Then, draw the shape in white.

For OpenGL, as we're using stencils, I optimized this:
        
        Draw the shape into the stencil buffer with 1s (rest is 0s).

        Draw the shape 4 times in black, only at places where stencil is 0,
        shifted. Stenciling saves quite a bit of rastering time here.

        Draw the contents, only at places where stencil is 1.

It's not perfect but it looks reasonable.

Unfortunately, there are some NVIDIA driver bugs w.r.t. stencil; I've
informed them and we'll see how it goes.

> In any case, "make runirregu" fails: ACCESS_VIOLATION occured outside 
> interpreter and JITed code.

Make sure you recompile "make compile gzzgl" first.

        Tuomas