**************************************************************** * GFA RAYTRACE USER NEWS ISSUE #3 FEBRUARY 1992 * **************************************************************** HALF PRICE SALE GFA US has been recently advertising 1/2 off *ALL* thier software titles from GFA Basic for Windows on down. For those readers who don't yet own GFA Raytrace or those who'd think it'd make a good gift to a fellow ST/STE owner - here's a chance to pick it up for less than mail-order prices. If you use Raytrace, but don't have v2.1 (a must for TOS 1.4/1.6) ask about the upgrade price, which should be even less. The ads say the offer ends February 28th - but do some sweet-talking and get them to extend the offer... (Tell them due to Atari Explorer's screwed up publishing schedule (which is appalling) you didn't see the 1/2 price ads till it was too late!) GFA USA's toll free number (orders only) 1-800-776-6GFA. RAY TO SPEC CONVERTER It bears repeating: The fully-working Shareware version of the Raytrace to Spectrum 512 converter is availiable from it's author for $5 - Write to Lonny Pursell re:Rayverter P.O. Box 145 Pandora, Ohio 45877. (A demo version which lets you convert for Spectrum view/slideshows, but not edit in Spectrum is on Genie and Compuserve as RAY2SPEC.ARC) CUSTOMIZE YOUR STARTUP SCREEN Its no coincidence that the file STARTSCREEN.SYS happens to be 50408 bytes long - the same size as an uncompressed pic. Just delete or disable the original pic by changing its name and rename one of your favorite .SUL pics to STARTSCREEN.SYS and it will appear as the opening screen when the program is run. You're not limited to just Raytrace pics - you could load any Degas, Neo, or Spectrum screen into Raytrace, then use the Save Screen function with compression set to off to save to .SUL format. WORKING WITH SPECTRUM After doing several dozen Spectrum conversions with the registered version of Lonny's converter, I've learned a few tricks to getting the best results enhancing a raytraced pic. The simplest and most effective is using the BLUR function of Antialias mode at a setting of 1 on the entire pic. (Use Mag mode to see the current setting is in the upper left corner of the screen) Antialias 9 is the default when Antialias mode is selected. Press A or B to toggle between it and Blur, which defaults to the setting of 1. I've found that with the higher number settings of Antialias, the results are less than perfect. It tends to streak horizontally along edges, muddying rather than smoothing, and using too many pixels to make the color transition. Blur 1 on the other hand appears to only use one or two pixels to make the transition and preserves a cleaner edge. AHHH, BUT I DIGRESS..... The rings of color you see on a raytraced sphere for example are known as the 'Mach Band Effect'. It's a common problem for anyone who writes a raytracing proram, and more so on a machine like the ST with only eight primary values to choose from. Shading algorithms like Phong or Gourard are used to compensate for these transitions on other raytracers, but apparantly not in GFA Raytrace. We're talking trade-offs here. GFA Raytrace is indeed a very fast raytracer! Especially when using 1/8 scale to quick-render a scene, we get feedback in almost realtime. This speed is due to 4 things: a low 320x200 resolution (fewer pixels to calculate), limited palette (not alot of colors to choose from), simple objects (not complex, multi-faceted objects like CAD 3-D), and 'quick and dirty' math (full shading algorithms are too processor intensive). It is on Dull objects that the banding is most apparant, and Spectrum is least effective.. The only real way to ease the transitions is to try finding the right colors and manually antialiasing the bands. Or, when selecting the color in Raytrace, try secondary rather than primary colors: a pure blue sphere (0,0,7) will band in all the blue shades, but try adding adding a tinge of red and green to make it slightly purplish (2,2,7) and you may find there will be narrower bands and more color transitions in your sphere. The placement of your main lamp(s) is also critical here - if your lamp is too far away or too close, you won't see all the transitions. Too distant, and a good portion if your object will be in blackness, too close and you'll lose several bands of color and the subtle shading of the object itself. Bright objects are a different breed. Most of thier banding will be narrower, and the banding on a sphere will be less noticable. The narrower bands will be tightly packed around the edges of the object giving a quick but smoother transition. The default SPOT ON setting in the Raytrace menu is tied to bright objects in that it controls the specular reflection on an object. Particularly on spheres, this will appear as a bright highlighted spot on an object, giving the appearance of a glossy surface reflecting the shine of the nearest lamp. I often use the Local mode of Spectrum's antialias to do a small drag-box around the highlight to smooth it out. The only other control we have over shading aside from choosing our materials or lamp placement is the 'SMEAR' option available from the Status menu. I think its rather aptly named, 'smudge' also comes to mind... But it's worth trying to see if it gives the effect you want. The reason I mention it is because the antialias/blur function of Spectrum does manage to get in between the pixels and help smooth things out on a blurred object, essentially dithering the area better than Raytrace itself does. NOW BACK TO SPECTRUM The above section was mentioned because Spectrum's antialising is mostly effective on the edges of objects and generally fails to smooth the center of objects where we need it most. Remember, once you've antialiased a whole screen, you'll need to exit and re-enter Antailias mode - Spectrum needs to re-analyze the picture's color palette if you want to try further antialiasing. Generally I do a Blur 1 on the entire pic, exit, then reenter and try Antialias using the drag box (local mode) on selected areas. (Again remember to avoid the far left edge of the screen - Spectrum will leave a vertical trail of pixels as it erroneously trys to anitalias the edge of the left color palette...) Editing out minor 'color problems' and other fine-tuning is again best done in Mag mode. Rather than searching the Color Martix for the shade you're looking for, just pick up the color directly in your pic. Usually the shade you want is in the area you're working on anyways. To select it, move the pencil tip over the pixel with the color you want, hold the CONTROL key, and right click. Wait. The palette will recalculate and the pointer will turn into an arrow, and now your chosen and active color will appear in the top and bottom borders. CONTROL-right click again over the pixel and the pointer will return to the pencil, and you're ready to edit. (Using the Control key bypasses bringing up the Color Matrix.) A reminder: If you don't have Spectrum 512 - E. Arthur Brown here in Minnesota swung a deal with Antic and is liquidating Spectrum for $14.95 (you just get the manual and disk, no 3-ring binder...) To order, give em a call at: 1 (800) 322-4405 M-F 8:30-4:30 CST. WHAT ABOUT ANIMATIONS? HUH? Don't mean to leave this aspect of Raytrace unmentioned, but it's taken me a full year to really get a good grip on the Edit mode of the program! This is not meant to reflect poorly on Raytrace, in fact, a year later I can say its really easy to use - it's just that there are _SO MANY_ variables at work in any given scene, I tend to get lost in experimentation and endless tweaking. Perhaps in the next issue I'll share some insights on animation in depth. 10 frames isn't enuff to do jaw-dropping movies with... But think of simple, repetitive concepts - water dripping from a faucet, a clock pendulum swinging, the bubbles in an aquarium rising - and focus on that one repeating motion. BUGS AND OTHER ANNOYING CRITTERS GFA Raytrace is by no means flawless. But considering the stunts the program is doing to the hardware to get 512 colors and constantly swap between split-rez modes, I'm suprised it is as stable as it is. Here's a few things to be aware of: What You Expect To See In The Mirror Ain't Always What You Get: I'm very fond of using mirrors: as backdrops, as objects, even as 'grounds' (especially interesting when texture mapped, try it! I've included a Spectrum pic with this newsletter showing how a mirrored rectangle was placed as a ground & texture mapped with a woodgrain pic to give the effect of a waxed wood floor) They give alot of depth cues to a 3-D scene shown on a 2-D screen. But don't expect picture perfect reflections (again quick and dirty math routines are the underlying culprit) either in terms of aspect or lighting or shadows. A great learning experience is to experiment with the MIRROR.WFL file included on your original disk and put your own objects in front of the mirrored rectangle. Move your observer, change your view angle, try loading a ground pic. You'll start to see inconsistencies - enuff to fool a causual look, but if you really look hard, you'll see what I mean. Like why is the ground lighter in the reflection when real mirrors absorb some of the light, or how shadows don't quite look like they 'ought to', etc. Note that the lamp is *exquisitly* placed in the MIRROR.WFL file - and why I strongly recommend leaving the lamp and mirror unchanged. They are at good angles to each other - if that lamp is moved much lower, you'll see 'glare' from the lamp in the mirror and it won't act like a mirror at all...(another bug?) Again, this .WFL is a great starting point for some really interesting raytraced scenes. Faster Redraws: Tho the Blitter helps (and is automatically turned on if present) Raytrace will not function properly with any of the sofware based screen accelerators - Turbo ST or Quick ST in any version I tried in color mode. I do think that monocrome users of Raytrace should have no problem, since 512/split mode is not used. Bright Objects: If you plan on using bright as a material selection, do so when you create the object and leave it that way! If you've ever had your ground suddenly become 'washed out' with bright white light it seems to be related to excessive twiddling with other material and percentage settings, then trying bright. Last night, I had a scene and ground map loaded, then added a bright object and my ground was washed out. Perhaps setting the ground -after- placing bright objects is the way to avoid it. But has happened often enough to indicate that bright objects are the culprit. No elegant solution, but deleting the bright objects will restore ground lighting to normal. If anyone discovers the trick or sequence to avoiding this, let me know! Dead Mousie Clicks: Occasionally mouse clicks won't register when a File Selector or alert is presented, either on filenames or [OK] [CANCEL]. Just hit return to accept default, then reenter and it always seems to work okay. Broken Windows: After long sessions of edit, trace, edit, etc. I've occasionally had the quad-view editor windows become messed up, with the borders and scroll bars improperly redrawn. Not deadly, but will make further editing impossible. Save and reboot. Also, sometimes lines in the perspective window will shoot off in crazy directions as you change view angles. In spite of what you see here, the picture will render what was drawn, not necessarily what you see. The 'Danger Zone': Not really a bug, but a limitation of 512 mode. The 'color problems' mentioned in the manual, and which you have no doubt seen onscreen can be frustrating to deal with. The minor ones are most easily edited out after conversion to Spectrum, avoiding changes and recalcs to your wireframes. But for whatever reasons, its most pronounced in an area 2/3rds of the way across the screen from the left edge. (we're starting to run out of colors!) Note this area in the Edit mode's perspective window as well - and try moving objects or shifting the view angle horizontally to move them to either side of this zone. UPLOAD! Those of you who do use the Spectrum converter - make a point of uploading some of your fave tracings to local bbs's. Its the best publicity you can give for GFA Raytrace, and will help insure demand for the program and its very survival as well. I'm doing what I can by uploading pics and the newsletters to the major online services. I have no idea how broadly these files are making it to other BBS's, but I do know that archives can and do travel far and fast in this era of telecommunications. Upload some pics - whether in Spectrum (or GIF format for other computers to view) and let them spread a thousand words about the abilities of the ST and GFA Raytrace! REDUNDANCY, AGAIN, TIMES TWO, REPEATED If you want Raytrace to survive, you'd better get off your duff while there's still a chance, and let GFA know that you expect TOS 2.x compatibility - It's that close to being a dead product! Tell them you just got a Mega STE, or the TOS 2 upgrade (it's okay to lie) and want to know _WHEN_ (not if) they will be releasing the update... I know I sound like a broken record - all the issues of Raytrace News have a sales pitch in them trying to rally your support. I don't know if it's working or not, or if it matters to many people. I just know that GFA needs to hear it from more than just me. I've done anything, everything I can think of to try to have some impact. Please help in any way you can, and let me know if or what response you get from GFA's end of the stick. Contact: GFA SYSTEMTECHNIK GMBH GFA DATA MEDIA UK GFA SOFTWARE TECH. Heerdter Standburg #30 Box 121 27 Congress Street D4000 Dusseldorf 11 Wokingham Berkshire Salem, Republic of RG11 1FA MA 01970-5523 GERMANY ENGLAND USA Dirk Van Assche Les Player John Barger To call GFA: America 1 (508) 744-0201 Fax: 1 (508) 744-8041 Direct Dial Germany (using ATT long distance): 011 49 211 55040 Direct Dial England (using ATT long distance): 011 44 734 794941 LIGHTENING UP As always, I'm interested in seeing the works of other Raytrace users, as well as sharing tips on using the program. Send whatever my way by mailing me a disk, writing or leaving me E-mail on GEnie: Nick S. Smith c/o GFA Raytrace User News 4406 5th Avenue South Minneapolis, MN 55409-2124 My GEnie mail address is S.SMITH65, or leave a post in the GFA area in the ST Rountables; Cat 22 - GFA, Topic 4 - GFA Raytrace.