kicad-developers team mailing list archive

[Torsten Hüter <torstenhtr@xxxxxx>]

Hi Dick,

On 04.11.2011 18:38, Dick Hollenbeck wrote:
> Hi Torsten,
>
> Some concerns about GAL:
>
> 1) what would be the cost of doing OPENGL_GAL::DrawGrid()
> using the GAL API itself?  (This would be better "self promotion", than using the opengl
> API, or cairo API, and would let this function be moved up into GAL itself.)

I believe I've implemented it this way, because I draw the lines in 
screen coordinates and I can use faster drawing methods rather than 
using the universal DrawLine(..) method. But I'll check if that could be 
unified for Cairo/OpenGL.

> 2) To best capitalize on the hardware acceleration, I wonder if we should not separate the
> generation of the opengl display lists, from actually repainting them on the screen.
> This means *two* functions, something like this:
>
> a) The scene has changed, create new opengl display lists.
>
> b) The on screen wxWindow containing a GAL has been resized or uncovered, simply use
> existing opengl display lists and ask opengl to put them on screen.

> This separation is what is being done in the existing 3d-viewer logic.    The board is
> only scanned one time to generate the display lists, and in the 3d-viewer of course the
> board never changes, so this separation of list generation and screen update becomes a big
> performance win.
>
> I have yet to find this separation 2) in the GAL.

You can do this already with the group methods.

BeginGroup() starts a new group, EndGroup() finishes the group - and you 
can simply draw the recorded graphics elements with DrawGroup().
For OpenGL basically a display list is created; for Cairo I'm using a 
deque and a simple state machine (later Cairo versions have now already 
a group function, I'll use that in the next versions).

Have a look at the group example in the test folder.

Thanks,
Torsten