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[REBOL] Re: deceleration !

From: greggirwin:mindspring at: 11-Oct-2002 11:32

Hi Fred, <<...i'm really surprise by the result of my test and i can't believe that drawing a simple circle (just one!) is so consequent. Or i must understand that in rebol drawing a circle is very complex and requiere a lot of compute that slow down performances. Maybe someone have another explanation to solve this question. >> There are some underlying conceptual issues, perhaps, and some other things to consider. First, in many drawing apps, the things you draw become just "bits on a background", which is fast and easy to display. In more capable apps, you may have lots of drawing objects which can be arbitrarily moved between layers (i.e. Z-ordered), etc. They tend to be highly optimized, and are the subject of an enormous amount of effort to keep their performance high. REBOL faces are very general and powerful. Every face uses the compositing engine and can have its own set of effects. The DRAW effect (as I understand it) has to be re-interpreted every time you show the face, which can be very slow, especially where fills and things are concerned. The little paint app I've seen holds its own pretty well, but I haven't seen Olivier's to see how it works or performs. Two things that affect face redrawing performance are 1) the size of the face, and 2) any other effects you have applied to it. Large faces are slow to paint, and other effects have to be re-rendered each time as well, which can bring things to a crawl if you're not careful. Their performance is good, but real-time, 24-bit compositing is a lot of work no matter how you look at it. HTH! --Gregg