[josm-dev] Fwd: GSoC: OpenGL view for JOSM

[Paul Hartmann]

On 17.03.2015 11:41, Michael Zangl wrote:
> Thanks for the feedback on my idea. Based on the feedback and the tests
> I made the past few days, I wrote a GSoC application.
>
> http://www.google-melange.com/gsoc/proposal/public/google/gsoc2015/michaelz/5750085036015616
>
> Feel free to leave feedback/your thoughts on this.

The comment section on the Melange platform doesn't seem to be public, 
so I post it here again:

Nice application! I'm all for setting realistic, achievable goals. But I 
was impressed, how much you could do in a small time, and hoped, you 
would aim for a full (or nearly full) replication of the Java2D 
rendering. A display without icons is kind of pointless, we don't need 
another Wireframe mode! Also, the "text along line" feature is an 
integral part of the standard style by now, and I wouldn't want to miss it.

Keep in mind, that you don't have to implement everything from scratch: 
As long as you can draw individual letters on screen, it should be 
possible to build on the existing code for "text along line". Yes, this 
often sounds simpler than it actually is, but you could at least put in 
on the agenda as a secondary goal.

I have looked at your code and was surprised, how complicated it is, to 
even draw a simple line. This makes me wonder: Have you investigated any 
higher level libraries, that offer a Java2D-like interface with a JOGL 
backend? First thing I found was this GLG2D [1]. I know you want to use 
VBO caching and other low-level techniques, but at least you could copy 
& paste some existing code, to make life easier.

Another big issue I have with your proposal, is that you seem to settle 
with a hard switch between JOGL and Java2D. I.e. either every layer and 
paint mode must support OpenGL or it isn't used at all. I think this is 
not really desirable as it restricts the usage a lot. It makes this a 
toy project and technology show-off, when it could be a general turbo 
mode that just works for basically every user (with fairly modern hardware).

You should investigate, how this can be fixed (can be during the work 
period). One option would be a Java2D->JOGL bridge like GLG2D. 
Alternatively, it seems to be possible to mix JOGL and Java2D in certain 
ways [2]. What are the performance implications? If you come to the 
conclusion, that it is not possible at all, this is fine, but the 
results should be documented properly.

[1] https://github.com/brandonborkholder/glg2d
[2] http://www.java-gaming.org/index.php?topic=10813.0