Super 3D Plotter II

Reviewed by John S.Davison

 

Issue 25

Jan/Feb 87

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I've always found computer manipulation and display of three dimensional images fascinating to watch. This 29.99 package from Demon Software brings the capability to any 8-bit Atari with 48K or more, a disk drive, and a joystick. Optionally, you can use a printer to produce hard copy of your 3D images.

BETTER PACKAGING NEEDED?

My first impression of the package wasn't favourable. The cheap plastic packaging and dot matrix printed 56 page instruction manual on gaudy green and yellow paper did little to convince me I was handling quality software. The bright green(!) double sided disk and poor quality keyboard reference card didn't help either. Demon Software have indicated however that they are improving the packaging and providing a fully typeset manual which I feel is essential for any software at this price.

DISPLAYING IMAGES

Booting up the disk produced a message saying that the program was on side 2! Side 1 contains data files - hmm.... different, anyway! The program's driven by a combination of menu selection, keyboard function keys, and direct joystick input, depending on what you're doing. This sounds messy, but in practice worked surprisingly well. In fact, I found the user interface to be unexpectedly friendly.

The manual is written mainly in the form of a tutorial, and starts you off displaying and manipulating 3D images
with the package. Some of these are fairly simple, such as a tube, while others, like the aircraft and TIE fighter, are considerably more complex.

Choosing 'Load' from the main menu produced a listing of the image files held on the disk. Selection of one of them resulted in a screen display showing a 3D wire frame image of a futuristic looking aircraft, positioned as if flying out of the screen towards you.

Console keys let you switch between high, medium and low resolution displays, produce black on white, or white on black display in high and medium resolution, and cycle background colours in low resolution mode. My preference was to use a black image on white background in high resolution mode.

Using the keyboards, you can then rotate the image about its X, Y or Z axis. The aircraft image can thus be viewed from any angle. Rotation is 'animated', in that once begun it continues, moving the image around the chosen axis a few degrees at a time while you watch. Speed of rotation may be continually varied by keyboard control. Maximum speed is governed by complexity of the image and resolution of the display. At maximum speed in hi-res mode, the aircraft rotated completely about the chosen axis in about 25 seconds, at about 2 screen displays per second. Incidentally, there's no flicker as the image is redrawn.

You can instantly freeze the image in any position, or slow down, or reverse the rotation as required. Also, you can rotate the image about any one, two or all three axes simultaneously, making the image 'tumble' on the screen as if in zero gravity.

A clever feature of the program is that as it rotates the image, the correct perspective is maintained. So if we rotate the aircraft from its original position through 180 degrees so it appears to be flying away from us, the tail fins now appear much larger than the nose. This gives the eye important visual clues as to the orientation of the image. A wire frame graphic can be very difficult to recognise without this.

Two more pairs of keys control viewing distance and magnification. Both control the size of the image on the screen, the former giving a gradual 'zoom' in or out effect, while the latter enlarges or reduces the image by a factor of two at each key depression, and alters the perspective effect. By using both together you can produce a perspective to suit your preference.

SOLID IMAGES

The program has the ability to 'remove hidden surfaces' from the displayed image, giving it a more 'solid' appearance. In effect, it removes the lines at the back of the image you can't normally see. In a wire frame type image these are on view all the time, of course. The only snag is, there's a lot more processing involved, so the speed of rotation is reduced by about half.

After removing hidden surfaces you can have the resultant image colour filled. This, surprisingly, seems to make little difference to the speed of rotation, but gives the image an even more realistic appearance. In medium and hi-res modes, three shades of fill are available, namely black, white and an artifacted pattern. In low-res mode, the image is filled with green, dark blue and purple, while the background can be set at any colour you like. As with the packaging, this wouldn't have been my choice of colours, but does clearly delineate the different surfaces of the image.

IMAGE TRAILS

Normally, the program erases an image before drawing the next one in a rotation sequence, but you can turn off the erase function. This results in a trail of images on the screen, leading to some fascinating 'computer art' effects. The effect can be further enhanced by switching into 'Exclusive-OR' mode, which changes the colour of line intersections, and also by offsetting the axes of rotation from their normal 'zero' position.

Saving a complete screen in Micropainter format is possible at any time. You could then load it into an art program, screen dump program, or other picture file utility for additional processing. A further feature lets you load a Micropainter format screen into this program as a background to your image.

These features give clues as to the possible practical uses for the package. How about drawing a simple 3D image, manipulating it to get the best viewing angle and perspective, and then loading it into an art program like Micropainter for adding detail and background work? Or turning off the erase function and doing the same thing with a trail of images? This could be a great help to struggling computer artists, and could also be a big time saver.

CREATING IMAGES

The tutorial continues by showing you how to create your own images, beginning with advice on how to prepare an image for input. For best results you really have to produce a paper and pencil drawing first, and work out the X, Y, and Z co-ordinates of the important points, and connecting lines between them. This can be hard work for a complex image!

Having defined your points and lines you can enter them in one of two ways. The 'fun' way is to use the Interactive Graphic Editor, which lets you draw the image on the screen using joystick (and occasional keyboard) input.
The tutorial steps you through the drawing of a cube with a hole cut through its centre. At first sight, even this simple example looks daunting, but in practice, using the Interactive Graphic Editor, it really is quite easy - I managed to produce a correct 3D image at the first attempt.

The interactive editor uses a 'rubber banding' technique for line drawing, like that used in most art programs. It's this feature plus the fact that the program tells you when you've connected with an existing point which makes accurate drawing possible. For real accuracy, though, there's another way of creating images, and that's by using the Data Editor. This isn't nearly so much fun as the interactive editor, as you key in all co-ordinates and point connections into tables. It's difficult to visualise the image as you're doing this, making it essential to do the paper and pencil drawing first. Either editor can be used for changing existing images, to correct mistakes, for example.

Following basic image construction techniques, the tutorial goes on to tackle more advanced features of the program, such as creating surfaces rather than lines, so you can use the hidden surface removal facility, merging of multiple images, and use of screen overlay facility. The manual also includes details on the technical aspects of the program, such as the mathematics used in calculating the 3D image rotation points, and how it was programmed.

PRINTING THE IMAGES

Two image printing facilities are provided, both intended for use with Epson compatible printers. The first of these is designed to work only with hi-res wire frame images, and produces an A4 size printout. The other works in medium or hi-res, with hidden surface removal and/or colour fill if required, and produces a printout filling one quarter of an A4 page. Both produce hard copy of good quality.

A BASIC program included in the package enables you to modify the print function to suit your printer. I didn't use this, as my Star SG10 is Epson compatible, and worked happily without changes being necessary. However, the BASIC program looked quite straightforward to use, assuming you know the control codes your printer needs to switch it into graphics mode.

CONCLUSIONS

After being put off initially by the packaging, I grew to like this program. I was impressed by its ease of use, thanks to its good user interface and clearly written manual (despite the awful colours, spelling mistakes, and dot matrix text). I was also impressed by its reliability and performance. No doubt the 16-bit ST could make it look silly, but considering the limitations of the 8-bit architecture, I think the author has done an excellent job.

For 29.99 I certainly expect better packaging and presentation, especially as far as the instruction manual is concerned. Indeed, the program deserves far better. This aside, Super 3D Plotter II should give you hours of pleasure and enjoyment if you're interested in exploring the world of three dimensional graphics. With the promised repackaging and improved manual my only major criticism will be removed and I can certainly give the program my full recommendation.

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