Re: [AD] Examples, current SVN

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On Sat, 2009-03-14 at 10:39 -0700, Evert Glebbeek wrote:
> The following examples are currently broken for me (in OS X):
> 
> ex_bitmap_target - Don't know if this is intentional or not, but when  
> using "forced bitmap locking", the red square leaves a ghost trail  
> behind when moving in the yellow square. "Drawing directly to bitmap"  
> shows no such trail.

It is intended, but the example probably should be changed. The contents
of the big rectangle are faded out with this:

al_draw_filled_rectangle(0, 0, W, H, al_map_rgba_f(1, 1, 0, 0.1));

So you see a ghost trail if you get low FPS. Probably best would be to
remove the fading part and run it at fixed FPS like other examples. On
the other hand, the fact how right now many examples do things
differently makes it easier to find bugs :)

> ex_membmp - the memory bitmap doesn't show up, all I see is a diagonal  
> line textured with the bitmap it's supposed to show.

It works here in Linux, but it's running only at about 1% of the speed
of the accelerated version.

> ex_draw - actually, I'm not sure whether this is a bug or not, but it  
> looks like it to me: on the first screen (with the boxes), the top- 
> left box has the outline and the filling aligned properly, but going  
> to the right the outline drifts away from the filling, similar going  
> down.

Yes, that's what I wanted to test with it. And yes, it shows a (or some)
bug(s).

The 4 boxes horizontally/vertically are drawn on fractional pixel
positions:

0.00 0.25 0.50 0.75

Without super-sampling, the rasterizer has to make a choice which pixels
to "light" - and as it seems, some HW makes odd choices. As does our
current software rasterization. If you edit the generated ex_draw.cfg,
you can enable super-sampling (change samples=0 to samples=4) to see how
OpenGL uses this.

> The second screen has the same problem with red outlines, and in  
> addition some of the pixels in the boxes are missing, overdrawn, or  
> outside the outline. Same for the circles in the second and third  
> examples. The lines in the last example have a similar problem of the  
> red guides not lining up properly.
> Let me know if it's useful for me to show a screenshot.

Yeah, we compared screenshots in IRC the other day, this is how it looks
here with my current NVidia's rasterizer:

No supersampling:
http://allefant.googlepages.com/Screenshot-UntitledWindow.png

4x supersampling:
http://allefant.googlepages.com/Screenshot-UntitledWindow-1.png

> 
> ex_expose - all I get now is a blank (white) window; this might be an  
> OS X problem.

Works here in X11.

-- 
Elias Pschernig <elias@xxxxxxxxxx>





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