Gremlin rewrite for OpenGL ES and possible optimization

Hi All,

I tried to rewrite Gremlin - make new widget based on existing code and contribute it. It made with using of recent OpenGL ES API (shaders/vertex buffers/etc.). The code is not ready to show yet, but I got all parts working and it is possible to make it handling bigger g-code files and do it fast enough. Currently big files simply excluded from preview. At first look, the problem is large Python trajectory arrays that filled one-by-one and then handled in Python again with lot of iterations. I rewrote it to use number of continous memory buffers (fixed size each) and it made a big change immediately. That is not the question, I hope I can show results soon. Just want to ask if anyone have interest in this new widget?

Another big deal is number of calls between C++ code and Python code. I did not measure it yet, but gcodemodule.cc does calls like this for any point in trajectory:
When it repeated n*thousand times, it becomes a bottleneck for sure. My idea is to modify methodand add an optional parameter for this to accept C method pointers for "straight_feed", "traverse", etc. So when this parameter passed, it will call C callbacks instead of python methods and do not do all this Python variable conversion back and forth.  Something like thisI believe this may be a huge performance win and I hope it does not violate any LinuxCNC development guidelines.
My question is to project maintainers. If I make this change and submit to Github to merge, will it be accepted? 

Not a developer but sounds great especially
for complex gcode or slower machines.

Probably best in a separate branch initially.
 

got it

I am very interested in seeing it. Is it a drop-in replacement for glcanon.py?

Yes, that is the goal.

One thing that is still 100% unclear for me is foam cutter visualization. There is some magic code in Gremlin for this. I never worked with such kind of machines. Is there any LinuxCNC documentation regarding foam cutter setup? Or may be one can explain in short?

Have a look at the foam simulation config 'configs/sim/axis/foam/axis_foam.ini'.

 

Basically it produces two separate previews, one for XY and one for UV

[edit]
Note that the Z,W height comes from the gcode lines (there are no actual Z or W axes)
(AXIS,XY_Z_POS,5)
(AXIS,UV_Z_POS,30)

[edit2]
The idea is that the two cones represent the end of a hot wire cutting through styrofoam
 
 

Thank you, that is clear now!