Am 09.04.2011 03:55, schrieb Michel Fortin:
On 2011-04-08 21:45:20 -0400, Adam D. Ruppe <destructiona...@gmail.com>
said:
Michel Fortin wrote:
One issue is that different operating system will draw things with
slightly different algorithms, which will result in slightly different
images, which might introduce glitches from platform to platform.
I actually hit an even bigger problem... Xlib can't actually draw
to XImages, and you don't have direct pixel access to XPixmaps
(it's the difference between being on the X Server and the client).
So, the lowest common denominator, using only system libraries, is
actually to allow *only* pixel access to Image, and move other
drawing over to the Window. (Specifically, a Painter struct that
ties to the window, so it can manage graphics contexts... yeah,
it's starting to get complicated again.)
What this means is if we want to draw to images, we've
got to spin our own algorithms. Which makes the different OS
algorithms moot - the direct screen drawing will be different, but
the images will all be the same. The downside is their functions
will lag a bit since I can't just wrap some C calls.
Personally, I wouldn't even bother with direct screen drawing in that
case. Direct screen drawing will need a different implementation for
each OS, which means a lot of duplicated effort that could be put in
implementing dependency-less cross-platform drawing primitives instead.
As for text, which library does the X server uses to draw text?
Freetype? You could link directly to it when you need to draw text...
and on other OS use similar OS services.
For the drawingt part. I'm currently working on a rednerer with scanline
algorithm. This will be completly OS-independent. It's in a single file
with 2kLOC, and rather low level drawing. I just render on a simple
ubyte-array, but it already support polygon-rendering, antialiasing and
different color-structs.
This is how it looks like for now:
http://img683.imageshack.us/i/testawa.jpg/
this takes currently 62ms to render, don't know if this is fast enough,
but can definitley improved.
°Matthias
