Screen(‘TransformTexture’) can’t do more than 2 source input images. The need for more than 2 has not arisen in the over 16 years of its existence until now.
Our moglmorpher() function, as demonstrated in MorphDemo.m, and MorphTextureDemo.m, does use an iterative multiply-accumulate approach to effectively input more than 2 images though for image and geometry morphing. The demo only shows two shapes, but in production this was used efficiently with at least 27 shapes on graphics hardware from 2009.
What’s the purpose of using 6 images?
Edit: Specifically, skimming your code, I wonder if what you try to do is simply what moglmorpher('morphTexture', ...) implements, for weighted mixing of various images together, as demonstrated in MorphTextureDemo.m.
-mario