Home » Archimedes archive » Acorn Computing » 1994 06 subscription disc.adf » 9406s » PD/3D_Tutor/3DText
PD/3D_Tutor/3DText
This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.
Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.
| Tape/disk: | Home » Archimedes archive » Acorn Computing » 1994 06 subscription disc.adf » 9406s |
| Filename: | PD/3D_Tutor/3DText |
| Read OK: | ✔ |
| File size: | 1EED bytes |
| Load address: | 0000 |
| Exec address: | 0000 |
File contents
Since the 1980's, several films have been screened that feature 3D vision. The effect can be quite fantastic - depending on the technique used. Probably the most well known method is using the red/green glasses, but this does have the disadvantage that colour cannot be used. Another technique is using polarised light. This requires two projectors which polarise the beams of light differently (90� 'apart'). The glasses then block out one of the beams by having polarised lenses. This is debatably the most effective method, allowing full colour. Another form of three dimensional vision is to have a single screen that flickers between the display for the left and right eyes. The glasses are then synchronised to do the same. The Sega system uses this form, but it suffers from a very flickery image. Because the average user does not have access to polarised light projectors or 'flickery' glasses, the first method is a good choice to demonstrate the 3D effect. The first thing we must understand before we venture into the world of 3D is how the eye perceives 'depth'. Our eyes, surprisingly enough, move independently. They move so as to focus in on an object. When an object is close to 'infinity' (as far away as possible) our eyes are near parallel, that is point directly ahead and each eyes' line of sight converges a long distance away. When our eyes point near parallel, our brain assumes the object to be a long way away. When an object is near, the eyes swing towards into other, converging at a closer point. This can be seen when somebody tries to look at their nose. If the eyes point inwards, our brain believes the object to be close. Now, how do we convert that theory onto the screen? Well, under normal circumstances, each eyes' line of sight converges at the screen. If an object is to be seen behind the monitor (further away), we must instruct each eye to swing outwards, towards the parallel. This can be expressed as : the left eye's image must be further to the left, and the right eye's image must be further to the right. From this, we should realise that the image passed to the left eye should be on the left, and the image for the right eye, on the right. Therefore, we can expect forward projections (in front of the monitor) to have the right eye's image at the left, and the left image at the right. This will make the lines of sight converge before the screen. Note however, that the distance between the left and right images should not exceed the distance between each eye, otherwise the 3D effect is lost. Indeed, due to the inability to exactly match the colour of the glasses, a separation of about 32 OS units is all we can expect. Now is where the glasses come in - separating the left eye's image and the right eye's. The lenses in each eye are a different colour - normally red and green, or red and blue. The glasses I used were red in the left eye and blue in the right. The same glasses could possibly be obtained from your local cinema, as they were used for the film, "Freddy's Dead". Anyway, one lens will totally block out the colour of the other. Therefore, by making the left image the colour of the left lens, and the right image the colour of the right lens, it is possible to separate the picture on the screen. Probably the hardest part of creating a 3D image is finding the exact colour of each lens. The simplest way of doing this is to run listing one (found on the free subscription disc). It will initially draw a red circle in the centre of the screen. Place a lens over it and alter the colour (which is displayed as three figures at the top of the screen) by using the keys as described. When the circle appears as dark as possible in one lens, but is still bright in the other, note down the colour numbers (and which lens it was visible in) and repeat with the other lens. You may find all this easier in a dark room. An example of the sort of effect that can be achieved with the information described here can be seen with listing two - a three dimensional star field. Close all the curtains and doors - the 3D effect can best be seen in total darkness - and run the program. If you own a television, you will notice a poor effect, if any. The only way to avoid this is to use a good quality PAL encoder, or use a monitor. The better the quality of the monitor, the more amazing the effect. If you can see 'ghosting', that is seeing both red and blue (or whatever colours the lenses are) lines, try moving away from the screen more - on a good multisync, it is possible to sit normally at the computer and still see a clear picture. If you find stars a little boring, take a look at listing three. This is the source code to create the module '3DPlotMod'. This module provides one SWI that can be accessed from BASIC, or most other languages. This function allows 3D vector graphics to be produced, by passing the x,y and z coordinates. The appropriate red and blue shapes will be drawn. To use it from BASIC, for example, you should enter : SYS "3D_Plot",plot action,x,y,z x,y and z are the coordinates of the line, arc or whatever you wish to draw. The plot action parameter is the same as for VDU25 (Plot). For those of you without PRM, here's a summary of the codes : All codes can be expressed as "<base> + <action>". the Base number tells the computer what shap you wish to draw. Action tells the computer how you want to draw it. The base values are as follows : 0 - draw a line, or move to the point 64 - plot a point 80 - draw a filled triangle 96 - draw a filled rectangle 112 - draw a filled parallelogram 144 - draw a circle outline 152 - draw a filled circle 160 - draw an arc 168 - draw a segment 176 - draw a sector 192 - draw an ellipse outline 200 - draw a filled ellipse The action values that should be added to the above bases are as follows : 0 - move relative to the last position visited (MOVE BY) 1 - draw relative to the last position visited 4 - move to the given position 5 - draw at the given position Codes 0 and 1 can be illustrated : If the last point you moved (or drew) to was 400,600 and you issued a move by (value 0) 100,-200 the new position would be 500,400. As an example, let us draw a line from 300,676,375 to 274,607,374 What you must do is : Move to one end ... SYS "3D_Plot",4,300,676,375 And then draw a line to the other ... SYS "3D_Plot",5,274,607,374 To draw a more complex shape, such as a triangle, move to the two corners and issue a 85 (ie. 80 + 5) for the final corner. Listing four is a final summary of the ideas described here. It contains the start-field from listing two, and adds a spinning pyramid bouncing backwards and forwards. The pyramid is drawn in machine code for speed, and uses the 3DPlotMod for the vector graphics. Note that to run this program, you must have the Module 3DLines loaded - this can be achieved by double-clicking on the 3DPlotMod icon in the desktop. The application !3DSetup is a simple program that defines the colours used for the left and right lenses. This can be used to adjust the colours to suit you - everyones eyes' see light and colour differently. Run the application as normal by double- clicking on its icon. Then, to change the left lens colour, press 'L', or 'R' to change the right one. Then, follow the instructions on the screen. When you exit from the program (not by pressing Escape), the settings you have changed will be saved to disc. Note that this will not work if you are running !3DSetUp from an archive, ie. follow the instructions in the magazine on how to unpack the archive. From now on, all the programs will use these settings for their colours. Many thanks to Vincent Sanders and the local cinema for their tremendous support for this project and their help with the research into 3D techniques.
00000000 53 69 6e 63 65 20 74 68 65 20 31 39 38 30 27 73 |Since the 1980's| 00000010 2c 20 73 65 76 65 72 61 6c 20 66 69 6c 6d 73 20 |, several films | 00000020 68 61 76 65 20 62 65 65 6e 20 73 63 72 65 65 6e |have been screen| 00000030 65 64 20 74 68 61 74 20 66 65 61 74 75 72 65 20 |ed that feature | 00000040 0a 33 44 20 76 69 73 69 6f 6e 2e 20 54 68 65 20 |.3D vision. The | 00000050 65 66 66 65 63 74 20 63 61 6e 20 62 65 20 71 75 |effect can be qu| 00000060 69 74 65 20 66 61 6e 74 61 73 74 69 63 20 2d 20 |ite fantastic - | 00000070 64 65 70 65 6e 64 69 6e 67 20 6f 6e 20 74 68 65 |depending on the| 00000080 20 0a 74 65 63 68 6e 69 71 75 65 20 75 73 65 64 | .technique used| 00000090 2e 20 50 72 6f 62 61 62 6c 79 20 74 68 65 20 6d |. Probably the m| 000000a0 6f 73 74 20 77 65 6c 6c 20 6b 6e 6f 77 6e 20 6d |ost well known m| 000000b0 65 74 68 6f 64 20 69 73 20 75 73 69 6e 67 20 74 |ethod is using t| 000000c0 68 65 20 0a 72 65 64 2f 67 72 65 65 6e 20 67 6c |he .red/green gl| 000000d0 61 73 73 65 73 2c 20 62 75 74 20 74 68 69 73 20 |asses, but this | 000000e0 64 6f 65 73 20 68 61 76 65 20 74 68 65 20 64 69 |does have the di| 000000f0 73 61 64 76 61 6e 74 61 67 65 20 74 68 61 74 20 |sadvantage that | 00000100 0a 63 6f 6c 6f 75 72 20 63 61 6e 6e 6f 74 20 62 |.colour cannot b| 00000110 65 20 75 73 65 64 2e 20 41 6e 6f 74 68 65 72 20 |e used. Another | 00000120 74 65 63 68 6e 69 71 75 65 20 69 73 20 75 73 69 |technique is usi| 00000130 6e 67 20 70 6f 6c 61 72 69 73 65 64 20 0a 6c 69 |ng polarised .li| 00000140 67 68 74 2e 20 54 68 69 73 20 72 65 71 75 69 72 |ght. This requir| 00000150 65 73 20 74 77 6f 20 70 72 6f 6a 65 63 74 6f 72 |es two projector| 00000160 73 20 77 68 69 63 68 20 70 6f 6c 61 72 69 73 65 |s which polarise| 00000170 20 74 68 65 20 62 65 61 6d 73 20 6f 66 20 0a 6c | the beams of .l| 00000180 69 67 68 74 20 64 69 66 66 65 72 65 6e 74 6c 79 |ight differently| 00000190 20 28 39 30 b0 20 27 61 70 61 72 74 27 29 2e 20 | (90. 'apart'). | 000001a0 54 68 65 20 67 6c 61 73 73 65 73 20 74 68 65 6e |The glasses then| 000001b0 20 62 6c 6f 63 6b 20 6f 75 74 20 6f 6e 65 20 0a | block out one .| 000001c0 6f 66 20 74 68 65 20 62 65 61 6d 73 20 62 79 20 |of the beams by | 000001d0 68 61 76 69 6e 67 20 70 6f 6c 61 72 69 73 65 64 |having polarised| 000001e0 20 6c 65 6e 73 65 73 2e 20 54 68 69 73 20 69 73 | lenses. This is| 000001f0 20 64 65 62 61 74 61 62 6c 79 20 74 68 65 20 0a | debatably the .| 00000200 6d 6f 73 74 20 65 66 66 65 63 74 69 76 65 20 6d |most effective m| 00000210 65 74 68 6f 64 2c 20 61 6c 6c 6f 77 69 6e 67 20 |ethod, allowing | 00000220 66 75 6c 6c 20 63 6f 6c 6f 75 72 2e 0a 41 6e 6f |full colour..Ano| 00000230 74 68 65 72 20 66 6f 72 6d 20 6f 66 20 74 68 72 |ther form of thr| 00000240 65 65 20 64 69 6d 65 6e 73 69 6f 6e 61 6c 20 76 |ee dimensional v| 00000250 69 73 69 6f 6e 20 69 73 20 74 6f 20 68 61 76 65 |ision is to have| 00000260 20 61 20 73 69 6e 67 6c 65 20 0a 73 63 72 65 65 | a single .scree| 00000270 6e 20 74 68 61 74 20 66 6c 69 63 6b 65 72 73 20 |n that flickers | 00000280 62 65 74 77 65 65 6e 20 74 68 65 20 64 69 73 70 |between the disp| 00000290 6c 61 79 20 66 6f 72 20 74 68 65 20 6c 65 66 74 |lay for the left| 000002a0 20 61 6e 64 20 72 69 67 68 74 20 0a 65 79 65 73 | and right .eyes| 000002b0 2e 20 54 68 65 20 67 6c 61 73 73 65 73 20 61 72 |. The glasses ar| 000002c0 65 20 74 68 65 6e 20 73 79 6e 63 68 72 6f 6e 69 |e then synchroni| 000002d0 73 65 64 20 74 6f 20 64 6f 20 74 68 65 20 73 61 |sed to do the sa| 000002e0 6d 65 2e 20 54 68 65 20 53 65 67 61 20 0a 73 79 |me. The Sega .sy| 000002f0 73 74 65 6d 20 75 73 65 73 20 74 68 69 73 20 66 |stem uses this f| 00000300 6f 72 6d 2c 20 62 75 74 20 69 74 20 73 75 66 66 |orm, but it suff| 00000310 65 72 73 20 66 72 6f 6d 20 61 20 76 65 72 79 20 |ers from a very | 00000320 66 6c 69 63 6b 65 72 79 20 69 6d 61 67 65 2e 0a |flickery image..| 00000330 42 65 63 61 75 73 65 20 74 68 65 20 61 76 65 72 |Because the aver| 00000340 61 67 65 20 75 73 65 72 20 64 6f 65 73 20 6e 6f |age user does no| 00000350 74 20 68 61 76 65 20 61 63 63 65 73 73 20 74 6f |t have access to| 00000360 20 70 6f 6c 61 72 69 73 65 64 20 6c 69 67 68 74 | polarised light| 00000370 20 0a 70 72 6f 6a 65 63 74 6f 72 73 20 6f 72 20 | .projectors or | 00000380 27 66 6c 69 63 6b 65 72 79 27 20 67 6c 61 73 73 |'flickery' glass| 00000390 65 73 2c 20 74 68 65 20 66 69 72 73 74 20 6d 65 |es, the first me| 000003a0 74 68 6f 64 20 69 73 20 61 20 67 6f 6f 64 20 0a |thod is a good .| 000003b0 63 68 6f 69 63 65 20 74 6f 20 64 65 6d 6f 6e 73 |choice to demons| 000003c0 74 72 61 74 65 20 74 68 65 20 33 44 20 65 66 66 |trate the 3D eff| 000003d0 65 63 74 2e 0a 0a 54 68 65 20 66 69 72 73 74 20 |ect...The first | 000003e0 74 68 69 6e 67 20 77 65 20 6d 75 73 74 20 75 6e |thing we must un| 000003f0 64 65 72 73 74 61 6e 64 20 62 65 66 6f 72 65 20 |derstand before | 00000400 77 65 20 76 65 6e 74 75 72 65 20 69 6e 74 6f 20 |we venture into | 00000410 74 68 65 20 0a 77 6f 72 6c 64 20 6f 66 20 33 44 |the .world of 3D| 00000420 20 69 73 20 68 6f 77 20 74 68 65 20 65 79 65 20 | is how the eye | 00000430 70 65 72 63 65 69 76 65 73 20 27 64 65 70 74 68 |perceives 'depth| 00000440 27 2e 20 4f 75 72 20 65 79 65 73 2c 20 0a 73 75 |'. Our eyes, .su| 00000450 72 70 72 69 73 69 6e 67 6c 79 20 65 6e 6f 75 67 |rprisingly enoug| 00000460 68 2c 20 6d 6f 76 65 20 69 6e 64 65 70 65 6e 64 |h, move independ| 00000470 65 6e 74 6c 79 2e 20 54 68 65 79 20 6d 6f 76 65 |ently. They move| 00000480 20 73 6f 20 61 73 20 74 6f 20 66 6f 63 75 73 20 | so as to focus | 00000490 0a 69 6e 20 6f 6e 20 61 6e 20 6f 62 6a 65 63 74 |.in on an object| 000004a0 2e 0a 57 68 65 6e 20 61 6e 20 6f 62 6a 65 63 74 |..When an object| 000004b0 20 69 73 20 63 6c 6f 73 65 20 74 6f 20 27 69 6e | is close to 'in| 000004c0 66 69 6e 69 74 79 27 20 28 61 73 20 66 61 72 20 |finity' (as far | 000004d0 61 77 61 79 20 61 73 20 70 6f 73 73 69 62 6c 65 |away as possible| 000004e0 29 20 0a 6f 75 72 20 65 79 65 73 20 61 72 65 20 |) .our eyes are | 000004f0 6e 65 61 72 20 70 61 72 61 6c 6c 65 6c 2c 20 74 |near parallel, t| 00000500 68 61 74 20 69 73 20 70 6f 69 6e 74 20 64 69 72 |hat is point dir| 00000510 65 63 74 6c 79 20 61 68 65 61 64 20 61 6e 64 20 |ectly ahead and | 00000520 65 61 63 68 20 0a 65 79 65 73 27 20 6c 69 6e 65 |each .eyes' line| 00000530 20 6f 66 20 73 69 67 68 74 20 63 6f 6e 76 65 72 | of sight conver| 00000540 67 65 73 20 61 20 6c 6f 6e 67 20 64 69 73 74 61 |ges a long dista| 00000550 6e 63 65 20 61 77 61 79 2e 20 57 68 65 6e 20 6f |nce away. When o| 00000560 75 72 20 65 79 65 73 20 0a 70 6f 69 6e 74 20 6e |ur eyes .point n| 00000570 65 61 72 20 70 61 72 61 6c 6c 65 6c 2c 20 6f 75 |ear parallel, ou| 00000580 72 20 62 72 61 69 6e 20 61 73 73 75 6d 65 73 20 |r brain assumes | 00000590 74 68 65 20 6f 62 6a 65 63 74 20 74 6f 20 62 65 |the object to be| 000005a0 20 61 20 6c 6f 6e 67 20 0a 77 61 79 20 61 77 61 | a long .way awa| 000005b0 79 2e 0a 57 68 65 6e 20 61 6e 20 6f 62 6a 65 63 |y..When an objec| 000005c0 74 20 69 73 20 6e 65 61 72 2c 20 74 68 65 20 65 |t is near, the e| 000005d0 79 65 73 20 73 77 69 6e 67 20 74 6f 77 61 72 64 |yes swing toward| 000005e0 73 20 69 6e 74 6f 20 6f 74 68 65 72 2c 20 0a 63 |s into other, .c| 000005f0 6f 6e 76 65 72 67 69 6e 67 20 61 74 20 61 20 63 |onverging at a c| 00000600 6c 6f 73 65 72 20 70 6f 69 6e 74 2e 20 54 68 69 |loser point. Thi| 00000610 73 20 63 61 6e 20 62 65 20 73 65 65 6e 20 77 68 |s can be seen wh| 00000620 65 6e 20 73 6f 6d 65 62 6f 64 79 20 0a 74 72 69 |en somebody .tri| 00000630 65 73 20 74 6f 20 6c 6f 6f 6b 20 61 74 20 74 68 |es to look at th| 00000640 65 69 72 20 6e 6f 73 65 2e 20 49 66 20 74 68 65 |eir nose. If the| 00000650 20 65 79 65 73 20 70 6f 69 6e 74 20 69 6e 77 61 | eyes point inwa| 00000660 72 64 73 2c 20 6f 75 72 20 62 72 61 69 6e 20 0a |rds, our brain .| 00000670 62 65 6c 69 65 76 65 73 20 74 68 65 20 6f 62 6a |believes the obj| 00000680 65 63 74 20 74 6f 20 62 65 20 63 6c 6f 73 65 2e |ect to be close.| 00000690 0a 0a 4e 6f 77 2c 20 68 6f 77 20 64 6f 20 77 65 |..Now, how do we| 000006a0 20 63 6f 6e 76 65 72 74 20 74 68 61 74 20 74 68 | convert that th| 000006b0 65 6f 72 79 20 6f 6e 74 6f 20 74 68 65 20 73 63 |eory onto the sc| 000006c0 72 65 65 6e 3f 20 57 65 6c 6c 2c 20 75 6e 64 65 |reen? Well, unde| 000006d0 72 20 0a 6e 6f 72 6d 61 6c 20 63 69 72 63 75 6d |r .normal circum| 000006e0 73 74 61 6e 63 65 73 2c 20 65 61 63 68 20 65 79 |stances, each ey| 000006f0 65 73 27 20 6c 69 6e 65 20 6f 66 20 73 69 67 68 |es' line of sigh| 00000700 74 20 63 6f 6e 76 65 72 67 65 73 20 61 74 20 74 |t converges at t| 00000710 68 65 20 0a 73 63 72 65 65 6e 2e 20 49 66 20 61 |he .screen. If a| 00000720 6e 20 6f 62 6a 65 63 74 20 69 73 20 74 6f 20 62 |n object is to b| 00000730 65 20 73 65 65 6e 20 62 65 68 69 6e 64 20 74 68 |e seen behind th| 00000740 65 20 6d 6f 6e 69 74 6f 72 20 28 66 75 72 74 68 |e monitor (furth| 00000750 65 72 20 0a 61 77 61 79 29 2c 20 77 65 20 6d 75 |er .away), we mu| 00000760 73 74 20 69 6e 73 74 72 75 63 74 20 65 61 63 68 |st instruct each| 00000770 20 65 79 65 20 74 6f 20 73 77 69 6e 67 20 6f 75 | eye to swing ou| 00000780 74 77 61 72 64 73 2c 20 74 6f 77 61 72 64 73 20 |twards, towards | 00000790 74 68 65 20 0a 70 61 72 61 6c 6c 65 6c 2e 20 54 |the .parallel. T| 000007a0 68 69 73 20 63 61 6e 20 62 65 20 65 78 70 72 65 |his can be expre| 000007b0 73 73 65 64 20 61 73 20 3a 20 74 68 65 20 6c 65 |ssed as : the le| 000007c0 66 74 20 65 79 65 27 73 20 69 6d 61 67 65 20 6d |ft eye's image m| 000007d0 75 73 74 20 62 65 20 0a 66 75 72 74 68 65 72 20 |ust be .further | 000007e0 74 6f 20 74 68 65 20 6c 65 66 74 2c 20 61 6e 64 |to the left, and| 000007f0 20 74 68 65 20 72 69 67 68 74 20 65 79 65 27 73 | the right eye's| 00000800 20 69 6d 61 67 65 20 6d 75 73 74 20 62 65 20 66 | image must be f| 00000810 75 72 74 68 65 72 20 74 6f 20 0a 74 68 65 20 72 |urther to .the r| 00000820 69 67 68 74 2e 20 46 72 6f 6d 20 74 68 69 73 2c |ight. From this,| 00000830 20 77 65 20 73 68 6f 75 6c 64 20 72 65 61 6c 69 | we should reali| 00000840 73 65 20 74 68 61 74 20 74 68 65 20 69 6d 61 67 |se that the imag| 00000850 65 20 70 61 73 73 65 64 20 74 6f 20 0a 74 68 65 |e passed to .the| 00000860 20 6c 65 66 74 20 65 79 65 20 73 68 6f 75 6c 64 | left eye should| 00000870 20 62 65 20 6f 6e 20 74 68 65 20 6c 65 66 74 2c | be on the left,| 00000880 20 61 6e 64 20 74 68 65 20 69 6d 61 67 65 20 66 | and the image f| 00000890 6f 72 20 74 68 65 20 72 69 67 68 74 20 0a 65 79 |or the right .ey| 000008a0 65 2c 20 6f 6e 20 74 68 65 20 72 69 67 68 74 2e |e, on the right.| 000008b0 20 54 68 65 72 65 66 6f 72 65 2c 20 77 65 20 63 | Therefore, we c| 000008c0 61 6e 20 65 78 70 65 63 74 20 66 6f 72 77 61 72 |an expect forwar| 000008d0 64 20 70 72 6f 6a 65 63 74 69 6f 6e 73 20 0a 28 |d projections .(| 000008e0 69 6e 20 66 72 6f 6e 74 20 6f 66 20 74 68 65 20 |in front of the | 000008f0 6d 6f 6e 69 74 6f 72 29 20 74 6f 20 68 61 76 65 |monitor) to have| 00000900 20 74 68 65 20 72 69 67 68 74 20 65 79 65 27 73 | the right eye's| 00000910 20 69 6d 61 67 65 20 61 74 20 74 68 65 20 0a 6c | image at the .l| 00000920 65 66 74 2c 20 61 6e 64 20 74 68 65 20 6c 65 66 |eft, and the lef| 00000930 74 20 69 6d 61 67 65 20 61 74 20 74 68 65 20 72 |t image at the r| 00000940 69 67 68 74 2e 20 54 68 69 73 20 77 69 6c 6c 20 |ight. This will | 00000950 6d 61 6b 65 20 74 68 65 20 6c 69 6e 65 73 20 0a |make the lines .| 00000960 6f 66 20 73 69 67 68 74 20 63 6f 6e 76 65 72 67 |of sight converg| 00000970 65 20 62 65 66 6f 72 65 20 74 68 65 20 73 63 72 |e before the scr| 00000980 65 65 6e 2e 0a 0a 4e 6f 74 65 20 68 6f 77 65 76 |een...Note howev| 00000990 65 72 2c 20 74 68 61 74 20 74 68 65 20 64 69 73 |er, that the dis| 000009a0 74 61 6e 63 65 20 62 65 74 77 65 65 6e 20 74 68 |tance between th| 000009b0 65 20 6c 65 66 74 20 61 6e 64 20 72 69 67 68 74 |e left and right| 000009c0 20 69 6d 61 67 65 73 20 0a 73 68 6f 75 6c 64 20 | images .should | 000009d0 6e 6f 74 20 65 78 63 65 65 64 20 74 68 65 20 64 |not exceed the d| 000009e0 69 73 74 61 6e 63 65 20 62 65 74 77 65 65 6e 20 |istance between | 000009f0 65 61 63 68 20 65 79 65 2c 20 6f 74 68 65 72 77 |each eye, otherw| 00000a00 69 73 65 20 74 68 65 20 33 44 20 0a 65 66 66 65 |ise the 3D .effe| 00000a10 63 74 20 69 73 20 6c 6f 73 74 2e 20 49 6e 64 65 |ct is lost. Inde| 00000a20 65 64 2c 20 64 75 65 20 74 6f 20 74 68 65 20 69 |ed, due to the i| 00000a30 6e 61 62 69 6c 69 74 79 20 74 6f 20 65 78 61 63 |nability to exac| 00000a40 74 6c 79 20 6d 61 74 63 68 20 74 68 65 20 0a 63 |tly match the .c| 00000a50 6f 6c 6f 75 72 20 6f 66 20 74 68 65 20 67 6c 61 |olour of the gla| 00000a60 73 73 65 73 2c 20 61 20 73 65 70 61 72 61 74 69 |sses, a separati| 00000a70 6f 6e 20 6f 66 20 61 62 6f 75 74 20 33 32 20 4f |on of about 32 O| 00000a80 53 20 75 6e 69 74 73 20 69 73 20 61 6c 6c 20 0a |S units is all .| 00000a90 77 65 20 63 61 6e 20 65 78 70 65 63 74 2e 0a 0a |we can expect...| 00000aa0 4e 6f 77 20 69 73 20 77 68 65 72 65 20 74 68 65 |Now is where the| 00000ab0 20 67 6c 61 73 73 65 73 20 63 6f 6d 65 20 69 6e | glasses come in| 00000ac0 20 2d 20 73 65 70 61 72 61 74 69 6e 67 20 74 68 | - separating th| 00000ad0 65 20 6c 65 66 74 20 65 79 65 27 73 20 0a 69 6d |e left eye's .im| 00000ae0 61 67 65 20 61 6e 64 20 74 68 65 20 72 69 67 68 |age and the righ| 00000af0 74 20 65 79 65 27 73 2e 20 54 68 65 20 6c 65 6e |t eye's. The len| 00000b00 73 65 73 20 69 6e 20 65 61 63 68 20 65 79 65 20 |ses in each eye | 00000b10 61 72 65 20 61 20 64 69 66 66 65 72 65 6e 74 20 |are a different | 00000b20 0a 63 6f 6c 6f 75 72 20 2d 20 6e 6f 72 6d 61 6c |.colour - normal| 00000b30 6c 79 20 72 65 64 20 61 6e 64 20 67 72 65 65 6e |ly red and green| 00000b40 2c 20 6f 72 20 72 65 64 20 61 6e 64 20 62 6c 75 |, or red and blu| 00000b50 65 2e 20 54 68 65 20 67 6c 61 73 73 65 73 20 49 |e. The glasses I| 00000b60 20 0a 75 73 65 64 20 77 65 72 65 20 72 65 64 20 | .used were red | 00000b70 69 6e 20 74 68 65 20 6c 65 66 74 20 65 79 65 20 |in the left eye | 00000b80 61 6e 64 20 62 6c 75 65 20 69 6e 20 74 68 65 20 |and blue in the | 00000b90 72 69 67 68 74 2e 20 54 68 65 20 73 61 6d 65 20 |right. The same | 00000ba0 0a 67 6c 61 73 73 65 73 20 63 6f 75 6c 64 20 70 |.glasses could p| 00000bb0 6f 73 73 69 62 6c 79 20 62 65 20 6f 62 74 61 69 |ossibly be obtai| 00000bc0 6e 65 64 20 66 72 6f 6d 20 79 6f 75 72 20 6c 6f |ned from your lo| 00000bd0 63 61 6c 20 63 69 6e 65 6d 61 2c 20 61 73 20 0a |cal cinema, as .| 00000be0 74 68 65 79 20 77 65 72 65 20 75 73 65 64 20 66 |they were used f| 00000bf0 6f 72 20 74 68 65 20 66 69 6c 6d 2c 20 22 46 72 |or the film, "Fr| 00000c00 65 64 64 79 27 73 20 44 65 61 64 22 2e 20 41 6e |eddy's Dead". 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