Alpha mask and video sent to different projector actors

  • I am working on a show with three large projection surfaces. Two triangular shaped "monoliths" and a cyc with some duvetyn draped on the edges that makes it non-rectilinear. I have been able to create a mask using an image and photoshop, and also by drawing the curves in a photoshop window projected onto the surface. The mask works great when using a projector actor with the alpha mask actor, but the projectors are at an angle that requires me to use 3d quad distort to get the content to look right. Doing this with the alpha mask actor messes up the mask. Is there a way to separate the alpha mask from the content and send it to a projector actor and use the 3d quad distort for the content? I have tried the add alpha channel actor different ways and tried the luminance key actor but I haven't had any luck.

    On a related note, and this may be the key to my problem, I can't get the layers to do anything. They don't make a difference when I adjust them no matter what the blend setting is. 
    I feel like there is an easy solution here, but I haven't found it. Any ideas are much appreciated. 

  • how about coming out of Isadora and into madmapper to deal with the distortion/masking?

  • Not a bad idea, but I don't have madmapper, and I imagine it will be difficult to get the company to purchase it for this show. is there something in isadora I can do? Or can I get photoshop to project through the projector to trace the lines for the mask? thanks,


  • Maybe some free apps can do basic mapping? I have not used this for years and it seems to gone through nice developement

  • I'm down to try another piece of software, especially if it's free. How do I use it with Isadora?

  • I figured it out. It seems too easy.  I just created the mask as a .png - black where masked and transparent where I want content. Send it to a quad distort, set to transparent and put in layer ten, Then any content, as long as in layers -10 thru 9, is masked AND individually controllable via their quad distort without distorting the mask. The alpha actors are not even necessary. I don't see why this was so tough to figure out. Now i can adjust the mask separately from the content. It wouldn't work earlier because the projector actor and the quad distort won't work together in layers. The quad is always on top it seems. Why is that?