@~As you'll probably guess, I've had this review for a-g-e-s ... @~sorry, JJ! Power Of Vision Raytracer Available on most machines - PC version on Disk 960 Reviewed by James Judge on an STe At some time or another we have all dabbled in computer art. Most of us have picked up the mouse, loaded up a paint package and started drawing, producing something no-one but you can recognise in a multi-coloured type of way. Some of us will have dabbled in fractals - those great patterns that are ever evolving on our computer screen and, when put into an animations, makes you feel quite sick. Very few of us will have dabbled with raytracing - the time when the mouse goes out the window and in comes some terribly complex maths, equations and a programming language! The first time I looked at raytracing was via ST Format and I didn't even bother to load the package in more than once - I tried to create a circle that was highly reflective and, after ten minutes of thought, the computer produced something I could have done in 30 seconds on a paint package. Willing to give the lark another go I looked at another package but read in the instructions not to get worried if the computer didn't seem to be doing much for a little while. Great, I thought, until I realised what a little while was - six to ten hours! Well, I couldn't have my computer hung up for that amount of time - I had games to play! Then, STF gave away POV on one of their coverdisks. I, after learning that it was a raytracer, quickly filed it away and looked at some other stuff on the disk. A few weeks ago I felt like trying something new and, waiting for a new shipment of software to arrive from Sue, I dug out POV, de- arced it and then set it tracing a shape that was supplied with the program. The file was called PACMAN so I had a fair idea a globe or circle was going to feature in the picture. I then sat down, watched a film and read a few chapters of my book. Exactly two hours, thirty nine minutes and twelve seconds later I was told that the picture had been rendered and saved to disk. I then loaded up a picture displayer/converter and loaded in the Targa file that had been created. Let me just explain a little bit about Atari graphic modes. We have got three resolutions - Low, medium and high. Low is the mode where we have got 16 colours (although 32 can be squeezed out of it), medium has got four and high only two. Low res is where all games etc. load up to, medium is for text adventures and serious software and high is just for serious software. The low resolution is where most painting takes place as we have got sixteen colours to use on the screen. That was until Spectrum 512 came along whereby a small AUTO loading program allowed the computer to display all of the colours on the screen at one time - 512 colours as it was produced on an FM. Then the 'e' came along with its Amiga equal palette and could easily be boosted up to near PC quality with a #200 graphics card. There was no real way that a home user could get the computer to display all 4,096 colours at once. The Mega and TT range allowed for more colours but still, in the main, most STs were limited to 512 colours for a static image and 32 for something like Ishar and 16 for all the other types of graphic. Then came along the Falcon with a lot of colours able to be displayed on the screen at once - equaling and (in most cases) exceeding the standard that 486 PCs had set at that time. With raytracing the more colours you have available to you to be put on the screen the better the final image will look like so, obviously, programmers were trying to squeeze that extra few colours out of a lowly ST. One programmer (there may be more, but I only know of one) was able to do that - allowing us to look at .IFFs (which had been done time and again) .GIFs (the same as .IFFs) .TGA (Targa, which is 24bit true colour) and .RAW (three files go to make up one image, making for (from what I've heard) excellent SVGA screens). Also this programmer put in his own little picture type (.PCS) which could, on an STe, output a whopping great 30,000+ colours at once! This is impossible - getting a supposed 24,000 colours from seemingly nowhere, but believe me it works. And the output is absolutely magnificent - the best, in fact, I have ever seen apart from stuff that has been rendered on TV (there was a series a while back looking at professional raytracing). Back to the review: The picture I was now presented with was a 3D Pacman shooting balls from his mouth and floating above a black, reflective floor that had blue bars in it that seemed to glow. Normally, even with a 512 colour picture, you can see colour transgression from one light shade to a darker one. There was none of this in the .PCS format. So, just what is raytracing? Well, raytracing is where you define basic shapes such as cylinders, spheres and cubes, give them a colour, texture and a shininess. You then place these shapes into a 3D environment using the standard X,Y and Z co-ordinates. Then you place a light source somewhere in the 3D view and a camera, or your viewpoint. Using a camera as your viewpoint will allow you to change that ever-so slightly however many times you want, so you could circle the objects that you had created, saving each render to disk and then loading the pictures up into a slideshow to produce some really good animations. After setting all these points using a programming language that isn't too dissimilar to English (just like AGT, actually) you save the file (you set all these conditions etc. out in a word processor and save them in ASCII format, just like AGT or TADS) and load up the raytracer program. Then you load up the file you have just created and have a very long tea-break. It is now the computer's turn. The way POV handles raytracing is by looking at the whole setup first (where the objects, light and viewpoint are) and then works out each individual line, shining light from the light source to an object, bouncing that light off of the object and so on. Actually it does what light, our eyes and our brain do all the time. Take a dark room, place a ball of wood and a ball of metal on the floor, stand in the corner and light the room with a bulb. The light rays then emit in straight lines from the bulb and hit everything in the room. The objects then absorbs part of that light (the light that comes from a light bulb is white light and is made up of seven colours - red, orange, yellow, green, blue, indigo and violet. The way objects get their colours is by absorbing certain parts of the white light and reflecting others, so a bright red jumper would absorb all but the red in white light and reflect the remaining red light into our eyes) and bounces the remaining around the room, depending on certain angle etc. The light then, eventually, reaches our eye and we register the brightness and colour to give ourselves full colour vision. In the ball of metal you would see reflections of the ball of wood, the walls and yourself because it reflects all colours etc. that hit it and the ball of wood would just be a ball of wood because it doesn't reflect all that well. That process is what the computer is doing and, as it is only a computer, can't do it the speed that normal light and we can. So, while it is bouncing the light rays around in its chips it is time for a long tea-break. The more objects and the more complex textures you have in your picture, the longer the whole process will take (more light to bounce around more things, you see). When the process has finished you should be left with a rather magnificent picture of something - if your programming was correct, that is. There is no way to check except for going over your text file with a fine tooth pick before you start the tracing program or it could end in tears - rather big ones when you realise that you have just wasted six hours of computing time. Also you must have quite a bit of disk space as pictures from POV can take anything between 10K to a massive 900K+ per screen. With the program there comes a few PD displaying utilities for the ST and Falcon and a hefty manual. There is a quickstart guide which only takes up 25 A4 pages, the actual manual takes up 111 pages of easy to follow text all about raytracing and how to work the program. Apart from being easy to use and giving great output the best thing about this program is that it is absolutely free - no shareware charge at all. If you want to get into raytracing this is THE program for you. If you are an expert this is also THE program for you this side of silly money. Overall great. If you want to see some breath taking examples of graphics on your ST that can be converted to an easy(er) format (Spectrum 512 which can be incorporated into STOS programmes) get this from Sue. The actual program comes on two arced files which deflate automatically onto two disks. One contains the actual program while the other contains the utilities and the documents. - o -