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History of RT!


rt.jpgI had a lot of fun reading yesterday's comments on the 'Hidden 3DS Max Display Mode' - thanks, everyone! :) Although it's not widely known, the RT button DOES have a function. I had a chat about it with Ton Roosendaal and he wrote the following article:

The "rt" button in Blender is there for developers to allow debugging or to hide testing. This value is by-definition not saved in (or read from) a Blender file, so you have to set it each time when you start Blender.

The name comes from an old convention I introduced in the NeoGeo animation studio long ago. We were saving a lot of files with variations of "temp" in the names, and it was never clear what to do with these. The deal we made was that any file named with "rt" would become a deleteable file, free for anyone to remove if you think it's in the way. I still use this a lot, check for example the file , which just is the debug image-of-the-day I upload while discussing coding issues.

What the name comes from I don't know really... I just happened to type it easily. Maybe it's because it has my initials? :)

Here are the current active "rt" hacks in Blender:

  • rt==1
    Hold ctrl, you can drag buttons around. Used to be 'UI edit mode'. Still saves file "butsetup" in current directory with button coordinates.
  • rt==2
    Use alternative OpenGL calls for reveiling UI refreshes like button highlights or pulldown menu updates. Seems to work faster on certain older ATI cards.
  • rt==2, rt==3
    3d window, Transform Manipulator in rotate mode, shows alternative designs
  • rt==8
    LSCM unwrap on selecting seams in face mode (ALT+Select) or on CTRL+E "mark seam"
  • rt!=0
    Debug print for each multilayer image loaded when image type is Image Sequence

Have fun!


Note: you can find the RT button in the Anim panel on the Scene Buttons window (F10)

About the Author

Avatar image for Bart Veldhuizen
Bart Veldhuizen

I have a LONG history with Blender - I wrote some of the earliest Blender tutorials, worked for Not a Number and helped run the crowdfunding campaign that open sourced Blender (the first one on the internet!). I founded BlenderNation in 2006 and have been editing it every single day since then ;-) I also run the Blender Artists forum and I'm Head of Community at Sketchfab.


  1. haha, you got us again!! april fools just never ends!! :P jk, that button thing is fun...reminds me of solitaire when you beat it, and all the cards start falling out and bouncing...maybe if we beat blender, it could have the same effect...

  2. ooooooooohhhhhh............ thats what its for...................
    I always thought that had something to do with rendering, i just could never find out.

  3. that rt==8 / LSCM is so great... I started once a thread on blenderartists to ask about that, but nobody knows... why isn't that excellent feature in the "real" version??... it's working great, what's the reason!!


  4. hehe - I've known about the rt button and what it's for for ages but I never could uncover what values do what (I suppose I could have looked at the code) - maybe these things should be documented better somewhere so that interested people can test them?...

    Just a thought.
    -epat. :)

  5. Malcolm Zaloon on

    Cool tricks, but actually RT == 5 make buttons appear like XSI skin button style. This is for future UI design?

  6. Malcolm Zaloon on

    The XSI thing is a little joke too.(my revenge for be fooled yesterday!)
    Only for enter in espirit of 1 april! Sorry ;)

  7. Am I the only one who got the 3DS MAX one working :P.

    Nah, I knew it was a joke, since I knew the Blender Devs wouldn't want to have a lawsuit in their hands. Still, this RT thing is pretty cool. Are there any other except the fw mentioned here?

  8. I just want to throw it out there that I have an ATi All-in-Wonder X1800XL, which is fairly recent. And after trying rt=2, the menus for the node editor which used to (for some reason) take ages to load its [spacebar] menu items now is like greased lightning. Thanks. Even if ATi cards are never fully figured out for Blender, this is a nice trick to have up my sleeve! :D

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