Re: fltk backend fix & mouse wheel scroll factor

[Michael Goffioul]

On Tue, Sep 29, 2009 at 10:22 AM, Shai Ayal <address@hidden> wrote:
> On Tue, Sep 29, 2009 at 11:12 AM, Michael Goffioul
> <address@hidden> wrote:
>> I see 2 problems with using bitmaps:
>> - they are not 3D
> But images are not 3D either right?

What I meant is that you won't be able to render images in
3D plot. You could still then use surface objects, but the
limitations I mentioned are still valid.

>> - you have a 1-to-1 pixel mapping between the bitmap and the screen,
>>  which is not what Matlab is doing; for instance a colorbar is just a
>>  c x 1 image object rendered in a m x n box (m>c, n>>1); you can do
>>  that seamlessly with textures
> I thought so too, but I found out this morning about glPixelZoom which
> will scale the bitmap:
> http://www.opengl.org/documentation/specs/man_pages/hardcopy/GL/html/gl/pixelzoom.html

That might help indeed.

>> Moreover, texture rendering is much faster than using bitmaps
> I suppose this will depend on the hardware. I would think that at
> least for software only implementations like mesa, bitmap would be
> faster since less processing is needed before drawing (e.g. no
> transformation matrix)

I'm not sure that it'll depend so much on the hardware. The bottleneck
will be the process of uploading the bitmap into the video memory, that
you'll have to do each time you want to draw the image (I don't see
any way of caching that). And to be honest, I have the impression that
graphics card are optimized for texture handling, not for direct buffer
access.

Anyway, if you want to give it try, please do. It's better than nothing.

Michael.