Hi Pieter, As far as I understand, draw_handles is called constantly for different rendering events (draw_lines, draw_solid, etc) in a certain ViewerContext. There's different strategies you can take to reduce the number of times your own stuff is calculated / drawn.
- Limit any drawing to happen only when the viewer is in 2D or 3D mode. Ex. // Don't draw anything unless viewer is in 3d mode: if (ctx->transform_mode() == VIEWER_2D) return; - Restrict any drawing to happen only during a specific drawing pass: Ex. if (!ctx->draw_unpickable_lines()) return; // Continue here. The following will only be executed when draw_handles() is called for a line drawing pass. - If the stuff you're trying to draw is rather heavy to calculate, build and compile a glList in build_handles(), and then call the list in draw_handles() to render it. - If you want to make sure you're only re-calculating your list (or whatever drawing routine) after certain things change (like a frame change, or a knob change), create a Hash instance, fill it up with all the variables whose change should trigger an update, and avoid re-calculation until the hash changes. Ex. Hash oldHash; Hash newHash; ... ... // in build_handles() oldHash.append(var1) // var1 being the variable one of your knobs is changing oldHash.append(var2) // etc oldHash.append(OutputContext().frame()) // to append the frame number // or just add the hash from the inputs if your drawing should also update if an incoming Iop changes oldHash.append(input0()->hash()) Hopefully that will give you a few ideas. I've gathered those over time following very useful advice from people in this list, and found them to be very useful when trying to have a bit more control over when exactly things should be drawn, and when to do any heavy lifting. Cheers, Ivan On Fri, May 20, 2011 at 1:05 PM, PieterVanHouten < nuke-dev-re...@thefoundry.co.uk> wrote: > hello > > so i have a small question about that. is draw_handles() the only place > where i can safely call and render my own opengl shaders and such into my > own render context? > > i found out that i can't rely on _open doing my gl rendering calls > (sometimes it works, sometimes it doesn't because of the render context that > seems to be locked) > > how often is draw_handles() updated? can't look into my code until > monday... > > i am looking for a function that gets updated every frame and after every > knob change. > > thank you > pieter > > _______________________________________________ > Nuke-dev mailing list > Nuke-dev@support.thefoundry.co.uk, http://forums.thefoundry.co.uk/ > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-dev > >
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