Goals of the test releases
j.j.ita@siep.shell.com
j.j.ita@siep.shell.com
Thu Nov 2 08:25:00 GMT 2000
Harold,
I agree with your strategy and think that you are probably 90% of
the way there on all the items with the exception of the keyboard which
is somewhat out of your hands. I think someone with little experience
in DirectX like me would just get in the way.
However, I would be like to help out on implementing the X graphic
primitives via Windows GDI. Could you give me some hints on which
documentation I should start looking at and what part of the code needs
twiddling with?
Joel
> -----Original Message-----
> From: Harold@compasstechnologies.com
> [ mailto:Harold@compasstechnologies.com ]
> Sent: Thursday, November 02, 2000 3:29 PM
> To: cygwin-xfree@sources.redhat.com
> Subject: Goals of the test releases
>
>
> Fantastic!
>
> It pleases me to hear that test 7 is working on Windows NT machines,
> finally.
>
> I think it would be helpful to state a few of the short-term
> goals for the
> test series:
> 1) Support screen output on both Windows NT and
> Windows 9X using the least-common denominator
> approach (offscreen frame buffer)
> 2) Use a new input scheme that will hopefully work with
> more keyboards, particularly non-English keyboards
> 3) Verify that the new input scheme is satisfactory
> 4) Display the X server in a window that behaves like a
> normal Windows window
>
> I'd say that goals 1 and 2 are nearly done, goal 3 has to be
> done by the
> users (I really need feedback from non-English users), and goal 4 is
> something I was putting off until I knew that goal 1 was at
> least possible.
>
> Here are the longer term goals for the test series:
> 1) Use a primary surface buffer on Windows NT
> 2) Use an offscreen buffer on Windows 9X
> 3) Use a command-line parameter to throttle the blits
> per second on Windows 9X
> 4) Produce a stable interim release for all users
> 5) Spark interest in the next phase of the project
>
> There is only one further goal of the test series that will
> be implemented
> after the above nine goals and that is to move away from
> frame buffers on
> both platforms. Moving away from frame buffers requires that
> we implement
> roughly 20 graphics functions that do things like drawing
> lines, circles,
> arcs, filling rectangles, etc. A quick investigation will
> reveal three
> technologies that seem plausible, if by name only, for
> implementing the
> graphics "primitives" as they are called.
> 1) DirectDraw
> 2) Direct3D
> 3) Windows GDI (Graphics Device Interface)
>
> A further investigation reveals the following benefits and
> drawbacks of each
> technology:
> 1) DirectDraw
> - No graphics primitives functions (no lines, arcs,
> rectangles, etc.)
> - Only performs bit block transfers
> - Not accelerated by the graphics hardware, as you
> have to write directly to the frame buffer
> - More suited to games and video playback, as you compose a scene
> off-screen, then blit the scene to the primary surface
> - We're already using DirectDraw as it was designed to be used
> - Offscreen drawing causes a performance hit even when you
> aren't drawing on the X server screen, as the offscreen
> surface has to be blitted to the monitor regardless
> of whether it has changed or not; this severely limits
> the low end of machines that we can support
> 2) Direct3D
> - No graphics primitives functions (no lines, arcs,
> rectangles, etc.)
> - Only draws points, lines, triangles, triangle fans,
> and triangle
> strips
> - Implementing graphics primitives would require converting
> arcs, rectangles, and such to triangles; this would involve
> quite a bit of mathematics
> - Direct3D doesn't have a concept of filling a rectangle
> with a color,
> Direct3D thinks of everything in textures; it would get
> pretty bizarre trying to create a texture for every color
> 3) Windows GDI
> + Graphics primitives functions (lines, arcs, rectangles, etc.)
> + Filled shapes (ellipses, rectangles, circles, etc.)
> + Pens for drawing lines
> + Already has a concept of fonts, and we may be able to adapt
> the standard X fonts to work with Windows
> + Windows GDI interacts with the graphics driver, so any hardware
> acceleration of primitives can be taken advantage of
> - Some GDI primitives don't correspond exactly to their
> counterpart
> X primitives; extra work we be required for those primitives
>
> Obviously, the Windows GDI seems like the way to go to implement our X
> graphics primitives functions. You may have seen claims that
> wrapping the
> Windows GDI for X servers results in poor performance; to
> that I have to
> ask, poor performance in relation to what? You see,
> emulating X graphics
> calls on Windows will never be as fast as your Linux box on the same
> hardware that is able to work with the graphics card more
> directly; on the
> other hand, almost anything will be faster than using 20% of
> your CPU time
> to blit the offscreen buffer to the primary surface.
>
> Well, that concludes the goals that I have for the test releases.
>
> Let me hear your ideas and your insights,
>
> Harold
>
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