CompuServe Messages

It works perfectly in a two-layer situation? Sure! Problem is, in a two-layer situation (where the second layer is one of the .IXPs in question), Alpha ITSELF is useless, since there are no other imaging layers for the Alpha to allow to show through and thus my objection still stands. Since we're talking two layers here where only one is an image and the other is just an effect, there is only ONE imaging layer, so anything where Alpha =0 is going to be BLACK! Why, gee, these effects will almost always ignore black areas ANYWAY (can you imagine trying to Hilight the BLACK pixels of an image, for instance?)! So it's STILL useless. Remember, we don't get to set an Alpha Threshhold for these effects, or a particular Key Alpha value. We ONLY get Whole Image (ignore Alpha entirely), Alpha >0 (any positive Alpha, including an Alpha of 1/256!), and Alpha =0 (****ALWAYS**** BLACK in your "two-layer situation"!!). On the second answer: so in other words, Alpha only does SUBtractive transparency, and Hilite, Flare, and Glow would need ADDitive transparency. I was afraid of that. Basically, if they DID generate Alpha, and you used that Alpha to apply it over a background, the portions of the Flares, Hilites, and Glows that extended over the background would look more like glass or celophane rather than like light as they should. It seems that the only way, then, to realistically composite Hilite, Flare, and Glow over an externally generated background (say, live video) would be to map the live video to a Keyframer geometry rectangle that exactly fills the camera's view and is behind all other geometry, and is linked to a Dummy that the camera and its target are also linked to so that the rectangle always fills the camera's view. That's fine, I suppose, if you don't need to animate the camera's FOV over the course of the animation — it'd be kinda hard to scale the rectangle to exactly match the camera's FOV. (Yet another reason you really should have implemented Object Cameras in R4.) One possible solution would require a new version of 3DS, namely, allocating one bit of Alpha in Video Post to determining ADDitive or SUBtractive transparency. Let's face it: you don't NEED a full 16 bits of Alpha channel! 15 is MORE than enough even with a full NTSC 2.2 gamma correction! Take the LSB of the Alpha as a switch — if 0, treat the remaining 15 bits of Alpha as SUBtracive Transparency. If 1, treat them as ADDitive Transparency. This way, Video Post's own Alpha can not only take Glow, Hilite, and Flare into account, but also such things as cones set to ADDitive Transparency to be used as "beams of light" in the actual geometry. Perhaps two bits could be so sacrificed, to allow for New and Old Subtractive, plus Additive, plus a fourth all-new use for Alpha. Of course, when writing files out to a 32-bit format such as TarGA, the Alpha channel would be reduced to 8 bits anyway and the extra flag bits would be ignored. An option could be selected in these cases to cause file Alpha to be set to 0 if the original Alpha is set to ADDitive, since external compositing programs/hardware couldn't duplicate the effect correctly. This still doesn't address the issue of documentation. All of the applicable routines in Yost IPAS Boutique #1 state in their instructions: Filter Whole Image, Alpha >0, Alpha =0. These radio buttons determine whether ______ acts on the entire image or is constrained by the alpha channel. ______ uses the alpha channel FROM THE QUEUE ITEM ABOVE IT if: Alpha >0 or Alpha =0 is selected; THE ITEM ABOVE IT IS A 32-BIT ENTRY; and the Use-Alpha button is set to Yes in 3D Studio's System Options dialog. Alpha >0 restricts _____ to THE PREVIOUS LAYER'S live image area (as defined in the alpha channel), whereas Alpha =0 restricts _____ to everything that's not in THE PREVIOUS LAYER'S live area (as excluded by the alpha channel.) For general use, leave the Filter parameter set to Whole Image. Please tell me how I could have determined that this meant every layer above the effect, not the immediately preceeding layer only, from what is written in that paragraph (and repeated four times in the manual, once each for Blur, Glow, Hilite, and Mono).