I'm not sure how you're compositing your colors, but the function you're using is not associative or commutative (I checked at lunch, mmm), so I don't think you can reverse order.
It's: a + b = (b1 + a1 (1 - b2), a2) Your function might need to be something like a + b = (b1*(1 - a2) + a1 (1 - b2), a2 b2), which is trivially commie and assoc, but doesn't feel right. Simply multiplying the alphas like this: a + b = (b1 + a1 (1 - b2), a2 b2) might make it associative, plus it 'feels' more natural to multiply the alphas.. but I'm not sure exactly from what model you derived your blending function so I could be really wrong. However, the behaviour of simply passing along the alpha of the first object seems suspicious. Anyways, hope you figure it out, really I'd derive a new function for the top down approach unless it had to be within tolerance of the results of you bottom up approach... then you'd have to analyze and find out what are the cases where you can drop bottom layers without losing end precision. Of course you can't drop the bottom (0,0), because that's what gives you your final alpha, which will always be 0. But maybe intermediate layers can be removed given that you find layers above them that are completely opaque. Then your optimization conditions could be simply filtering out all elements beneath such a layer. Sorry if this contains errors, but I gotta get back to work grinding the metals! -max --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
