Hello ericsoco, 

thanks darius.  MPE requires a PC for each display.  i'm not sure this is an option for me, but will keep it in mind.

What are the hardware routes you have tried ?

What about one big screen, and just draw the buffer image three times at the different positions? There's no need to copy and redraw the buffer... Or am I missing something ?

@jesse, my application is designed to draw to a canvas that's 2700x1600 because that's what i thought i'd be able to work with, and there's content that spreads across multiple screens.  if it was simple to draw everything in the three screens separately, i'd definitely consider that route.

@darius, i guess you're right -- don't need a separate computer for each screen for MPE.

Removed double post, because it was basically the same post. It's better to keep a discussion focused instead of spreading it over multiple threads.

Now on topic...

The best solution is that you fix your hardware route so that it will accept 3 horizontally placed screens as would normally be the case. Alternatively, you could consider adapting your sketch so it draws to 3 vertically placed screens, but I'm assuming this would take such refactoring an be so impractical, that you already chose the third best solution: copying pixels to facilitate your hardware setup. Indeed copy() and many of those methods are very slow. A probably faster solution would be to use the pixel array directly. To even improve on that speed you could use look-up tables to precompute coordinates. However what is likely to be the fastest solution is to use a GLSL fragment shader. Since you only have 1 input texture, 1 output texture and all you do is a little copying around, this should be possible.

@amnon.owed, sorry for the cross-post -- i realized it was moving into GL territory and wanted to get the attention of folks on the libraries list.  thanks for the suggestion; any tips on where to start with GLSL fragment shaders?  that's completely unknown territory for me.

Depends if you are using 1.5.1 or a 2.0 beta. If it's the latter, check this post and the examples that come with the release (because there have been api changes). If it's the former, check the GLGraphics library and this post for a few starting tips.

You could really also investigate the pixel array option. A quick test shows me that it's already a lot faster than copy (let alone 3 copies) even at a 900x4800 resolution. So it may be worthwile to check that option first.