Home » Archimedes archive » Acorn User » AU 1997-11 B.adf » Regulars » StarInfo/Holloway/!Shade/!Help
StarInfo/Holloway/!Shade/!Help
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 User » AU 1997-11 B.adf » Regulars |
| Filename: | StarInfo/Holloway/!Shade/!Help |
| Read OK: | ✔ |
| File size: | 1103 bytes |
| Load address: | 0000 |
| Exec address: | 0000 |
File contents
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| |
| S H A D E |
| |
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by Alex Holloway, 1997
Shade is a program which allows you to draw using the "shade bobs" effect seen in demos such as Xtreme. Shade is Risc PC only (24-bit colour), and requires at least 1Mb VRAM to work (a version for machines without VRAM is of course technically possible, but the display would be very small).
Keys are as follows:
- Draw using mouse (Select to draw)
- Insert: shows menu
- Delete: clears screen
- Print: saves screen.
The menu options are as follows:
- Change colour shift: allows you to specify how much of each colour to be added to or removed from the screen while drawing, takes integer values between -10 and +10 (higher values are possible but don't give the effect).
- Change brush type: allows you to select which sprite to use as a brush shape. Extra brushes can be created by adding sprites to the 'Brushes' sprite file inside !Shade. These should be 20x20 pixels in 2 colours, and will be recognised automatically by the program.
- Change background colour: takes input of values between 0 and 255 for red, green and blue. Note - this clears the screen, all previous drawings are lost.
- Change filename for screen save - allows you to specify a pathname to save to when 'Print' is pressed.
The first three options are also gone through when the program is first loaded. For these options, a zero can be entered by pressing Enter on a blank line.
HOW THE PROGRAM WORKS (a brief overview)
========================================
N.B. Please excuse my totally uncommented and unreadable Basic.
Lines up to 430 are for setting up and mainly involve getting the brush sprites sorted out, the main loop is lines 430 to 510.
x% is the current x position of the mouse, x2% is the previous x position of the mouse. (Similarly for y% and y2%).
When drawing, Shade takes points two at a time, and interpolates between them to create a continuous line - this is done by PROCdraw_across and PROCdraw_up. This is done with respect to either the horizontal or the vertical depending on whether the gradient of the line is greater or less than 1 (decided by PROCdraw).
For each position on the line, the assembler plot routine is called. Registers at start are as follows:
R0 - start address of screen memory
R1 - x location of plot
R2 - y location of plot
R3 - width of plot
R4 - height of plot
(Originally different sized brushes were planned, however I never got round to implementing this)
R5 - start address of mask, generated from sprite data when program is started up by PROCsetup_pixtable
R6 - address of block containing colour information (cols%)
R7 - brush type.
Lines 900 to 1050 do setup, translate the co-ordinates information into addresses to start and end the plot; the remainder is the actual plot code. This section goes through each memory location to be changed, checks if it isn't masked out, and if it isn't, splits out the colour components and adds (or subtracts) in the colour shift.
During the plotting process, registers are used as follows:
(if I remember correctly!)
R1 - shift for current colour (red/green/blue)
R2 - 8-bit value of current colour component of pixel
R6 - address of current position in colour info block
R7 - bit offset from 0 of current colour in pixel data
R8 - mask for current pixel loaded here
R9 - start address of position in plot, incremented with each pixel
R10 - end address of plot
R11 - colour data of current pixel
R12 - end address of current line to plot
It's probably possible to code all of this much more simply, but I couldn't work out how!
Lines 1490 onwards are the user interface, this should be fairly self-explanatory; a user sprite area, starting at sprite%, is used to store the current picture while the menu is being used. PROCsetcols makes sure that the text is in a readable colour no matter what the background colour is! 00000000 0a 0a 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |.. | 00000010 20 20 20 20 20 20 20 20 20 20 0a 20 20 20 20 20 | . | 00000020 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 00000030 20 20 20 20 20 20 20 20 20 20 2d 2d 2d 2d 2d 2d | ------| 00000040 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 0a 20 20 |-------------. | 00000050 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 00000060 20 20 20 20 20 20 20 20 20 20 20 20 20 7c 20 20 | | | 00000070 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 7c | || 00000080 0a 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |. | 00000090 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 000000a0 7c 20 20 53 20 20 48 20 20 41 20 20 44 20 20 45 || S H A D E| 000000b0 20 20 7c 0a 20 20 20 20 20 20 20 20 20 20 20 20 | |. | 000000c0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 000000d0 20 20 20 7c 20 20 20 20 20 20 20 20 20 20 20 20 | | | 000000e0 20 20 20 20 20 7c 0a 20 20 20 20 20 20 20 20 20 | |. | 000000f0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 00000100 20 20 20 20 20 20 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d | ----------| 00000110 2d 2d 2d 2d 2d 2d 2d 2d 2d 0a 20 20 20 20 20 20 |---------. | 00000120 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 00000130 20 20 20 20 20 20 20 20 20 0a 20 20 20 20 20 20 | . | 00000140 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 00000150 20 20 20 20 20 20 20 20 62 79 20 41 6c 65 78 20 | by Alex | 00000160 48 6f 6c 6c 6f 77 61 79 2c 20 31 39 39 37 0a 20 |Holloway, 1997. | 00000170 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 00000180 20 20 20 20 20 20 20 20 20 20 20 20 20 0a 20 20 | . | 00000190 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 000001a0 20 20 20 20 20 20 20 20 20 20 20 20 0a 20 20 53 | . S| 000001b0 68 61 64 65 20 69 73 20 61 20 70 72 6f 67 72 61 |hade is a progra| 000001c0 6d 20 77 68 69 63 68 20 61 6c 6c 6f 77 73 20 79 |m which allows y| 000001d0 6f 75 20 74 6f 20 64 72 61 77 20 75 73 69 6e 67 |ou to draw using| 000001e0 20 74 68 65 20 22 73 68 61 64 65 20 62 6f 62 73 | the "shade bobs| 000001f0 22 20 65 66 66 65 63 74 20 73 65 65 6e 20 69 6e |" effect seen in| 00000200 20 64 65 6d 6f 73 20 73 75 63 68 20 61 73 20 58 | demos such as X| 00000210 74 72 65 6d 65 2e 20 53 68 61 64 65 20 69 73 20 |treme. Shade is | 00000220 52 69 73 63 20 50 43 20 6f 6e 6c 79 20 28 32 34 |Risc PC only (24| 00000230 2d 62 69 74 20 63 6f 6c 6f 75 72 29 2c 20 61 6e |-bit colour), an| 00000240 64 20 72 65 71 75 69 72 65 73 20 61 74 20 6c 65 |d requires at le| 00000250 61 73 74 20 31 4d 62 20 56 52 41 4d 20 74 6f 20 |ast 1Mb VRAM to | 00000260 77 6f 72 6b 20 28 61 20 76 65 72 73 69 6f 6e 20 |work (a version | 00000270 66 6f 72 20 6d 61 63 68 69 6e 65 73 20 77 69 74 |for machines wit| 00000280 68 6f 75 74 20 56 52 41 4d 20 69 73 20 6f 66 20 |hout VRAM is of | 00000290 63 6f 75 72 73 65 20 74 65 63 68 6e 69 63 61 6c |course technical| 000002a0 6c 79 20 70 6f 73 73 69 62 6c 65 2c 20 62 75 74 |ly possible, but| 000002b0 20 74 68 65 20 64 69 73 70 6c 61 79 20 77 6f 75 | the display wou| 000002c0 6c 64 20 62 65 20 76 65 72 79 20 73 6d 61 6c 6c |ld be very small| 000002d0 29 2e 0a 20 20 0a 20 20 4b 65 79 73 20 61 72 65 |).. . Keys are| 000002e0 20 61 73 20 66 6f 6c 6c 6f 77 73 3a 0a 20 20 0a | as follows:. .| 000002f0 20 20 2d 20 44 72 61 77 20 75 73 69 6e 67 20 6d | - Draw using m| 00000300 6f 75 73 65 20 28 53 65 6c 65 63 74 20 74 6f 20 |ouse (Select to | 00000310 64 72 61 77 29 0a 20 20 0a 20 20 2d 20 49 6e 73 |draw). . - Ins| 00000320 65 72 74 3a 20 73 68 6f 77 73 20 6d 65 6e 75 0a |ert: shows menu.| 00000330 20 20 2d 20 44 65 6c 65 74 65 3a 20 63 6c 65 61 | - Delete: clea| 00000340 72 73 20 73 63 72 65 65 6e 0a 20 20 2d 20 50 72 |rs screen. - Pr| 00000350 69 6e 74 3a 20 73 61 76 65 73 20 73 63 72 65 65 |int: saves scree| 00000360 6e 2e 0a 20 20 0a 20 20 54 68 65 20 6d 65 6e 75 |n.. . The menu| 00000370 20 6f 70 74 69 6f 6e 73 20 61 72 65 20 61 73 20 | options are as | 00000380 66 6f 6c 6c 6f 77 73 3a 0a 20 20 0a 20 20 2d 20 |follows:. . - | 00000390 43 68 61 6e 67 65 20 63 6f 6c 6f 75 72 20 73 68 |Change colour sh| 000003a0 69 66 74 3a 20 61 6c 6c 6f 77 73 20 79 6f 75 20 |ift: allows you | 000003b0 74 6f 20 73 70 65 63 69 66 79 20 68 6f 77 20 6d |to specify how m| 000003c0 75 63 68 20 6f 66 20 65 61 63 68 20 63 6f 6c 6f |uch of each colo| 000003d0 75 72 20 74 6f 20 62 65 20 61 64 64 65 64 20 74 |ur to be added t| 000003e0 6f 20 6f 72 20 72 65 6d 6f 76 65 64 20 66 72 6f |o or removed fro| 000003f0 6d 20 74 68 65 20 73 63 72 65 65 6e 20 77 68 69 |m the screen whi| 00000400 6c 65 20 64 72 61 77 69 6e 67 2c 20 74 61 6b 65 |le drawing, take| 00000410 73 20 69 6e 74 65 67 65 72 20 76 61 6c 75 65 73 |s integer values| 00000420 20 62 65 74 77 65 65 6e 20 2d 31 30 20 61 6e 64 | between -10 and| 00000430 20 2b 31 30 20 28 68 69 67 68 65 72 20 76 61 6c | +10 (higher val| 00000440 75 65 73 20 61 72 65 20 70 6f 73 73 69 62 6c 65 |ues are possible| 00000450 20 62 75 74 20 64 6f 6e 27 74 20 67 69 76 65 20 | but don't give | 00000460 74 68 65 20 65 66 66 65 63 74 29 2e 0a 20 20 0a |the effect).. .| 00000470 20 20 2d 20 43 68 61 6e 67 65 20 62 72 75 73 68 | - Change brush| 00000480 20 74 79 70 65 3a 20 61 6c 6c 6f 77 73 20 79 6f | type: allows yo| 00000490 75 20 74 6f 20 73 65 6c 65 63 74 20 77 68 69 63 |u to select whic| 000004a0 68 20 73 70 72 69 74 65 20 74 6f 20 75 73 65 20 |h sprite to use | 000004b0 61 73 20 61 20 62 72 75 73 68 20 73 68 61 70 65 |as a brush shape| 000004c0 2e 20 45 78 74 72 61 20 62 72 75 73 68 65 73 20 |. Extra brushes | 000004d0 63 61 6e 20 62 65 20 63 72 65 61 74 65 64 20 62 |can be created b| 000004e0 79 20 61 64 64 69 6e 67 20 73 70 72 69 74 65 73 |y adding sprites| 000004f0 20 74 6f 20 74 68 65 20 27 42 72 75 73 68 65 73 | to the 'Brushes| 00000500 27 20 73 70 72 69 74 65 20 66 69 6c 65 20 69 6e |' sprite file in| 00000510 73 69 64 65 20 21 53 68 61 64 65 2e 20 54 68 65 |side !Shade. The| 00000520 73 65 20 73 68 6f 75 6c 64 20 62 65 20 32 30 78 |se should be 20x| 00000530 32 30 20 70 69 78 65 6c 73 20 69 6e 20 32 20 63 |20 pixels in 2 c| 00000540 6f 6c 6f 75 72 73 2c 20 61 6e 64 20 77 69 6c 6c |olours, and will| 00000550 20 62 65 20 72 65 63 6f 67 6e 69 73 65 64 20 61 | be recognised a| 00000560 75 74 6f 6d 61 74 69 63 61 6c 6c 79 20 62 79 20 |utomatically by | 00000570 74 68 65 20 70 72 6f 67 72 61 6d 2e 0a 20 20 0a |the program.. .| 00000580 20 20 2d 20 43 68 61 6e 67 65 20 62 61 63 6b 67 | - Change backg| 00000590 72 6f 75 6e 64 20 63 6f 6c 6f 75 72 3a 20 74 61 |round colour: ta| 000005a0 6b 65 73 20 69 6e 70 75 74 20 6f 66 20 76 61 6c |kes input of val| 000005b0 75 65 73 20 62 65 74 77 65 65 6e 20 30 20 61 6e |ues between 0 an| 000005c0 64 20 32 35 35 20 66 6f 72 20 72 65 64 2c 20 67 |d 255 for red, g| 000005d0 72 65 65 6e 20 61 6e 64 20 62 6c 75 65 2e 20 4e |reen and blue. N| 000005e0 6f 74 65 20 2d 20 74 68 69 73 20 63 6c 65 61 72 |ote - this clear| 000005f0 73 20 74 68 65 20 73 63 72 65 65 6e 2c 20 61 6c |s the screen, al| 00000600 6c 20 70 72 65 76 69 6f 75 73 20 64 72 61 77 69 |l previous drawi| 00000610 6e 67 73 20 61 72 65 20 6c 6f 73 74 2e 0a 20 20 |ngs are lost.. | 00000620 0a 20 20 2d 20 43 68 61 6e 67 65 20 66 69 6c 65 |. - Change file| 00000630 6e 61 6d 65 20 66 6f 72 20 73 63 72 65 65 6e 20 |name for screen | 00000640 73 61 76 65 20 2d 20 61 6c 6c 6f 77 73 20 79 6f |save - allows yo| 00000650 75 20 74 6f 20 73 70 65 63 69 66 79 20 61 20 70 |u to specify a p| 00000660 61 74 68 6e 61 6d 65 20 74 6f 20 73 61 76 65 20 |athname to save | 00000670 74 6f 20 77 68 65 6e 20 27 50 72 69 6e 74 27 20 |to when 'Print' | 00000680 69 73 20 70 72 65 73 73 65 64 2e 0a 20 20 0a 20 |is pressed.. . | 00000690 20 54 68 65 20 66 69 72 73 74 20 74 68 72 65 65 | The first three| 000006a0 20 6f 70 74 69 6f 6e 73 20 61 72 65 20 61 6c 73 | options are als| 000006b0 6f 20 67 6f 6e 65 20 74 68 72 6f 75 67 68 20 77 |o gone through w| 000006c0 68 65 6e 20 74 68 65 20 70 72 6f 67 72 61 6d 20 |hen the program | 000006d0 69 73 20 66 69 72 73 74 20 6c 6f 61 64 65 64 2e |is first loaded.| 000006e0 20 46 6f 72 20 74 68 65 73 65 20 6f 70 74 69 6f | For these optio| 000006f0 6e 73 2c 20 61 20 7a 65 72 6f 20 63 61 6e 20 62 |ns, a zero can b| 00000700 65 20 65 6e 74 65 72 65 64 20 62 79 20 70 72 65 |e entered by pre| 00000710 73 73 69 6e 67 20 45 6e 74 65 72 20 6f 6e 20 61 |ssing Enter on a| 00000720 20 62 6c 61 6e 6b 20 6c 69 6e 65 2e 0a 20 20 0a | blank line.. .| 00000730 20 20 0a 20 20 48 4f 57 20 54 48 45 20 50 52 4f | . HOW THE PRO| 00000740 47 52 41 4d 20 57 4f 52 4b 53 20 28 61 20 62 72 |GRAM WORKS (a br| 00000750 69 65 66 20 6f 76 65 72 76 69 65 77 29 0a 20 20 |ief overview). | 00000760 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d |================| * 00000780 3d 3d 3d 3d 3d 3d 3d 3d 0a 20 20 4e 2e 42 2e 20 |========. N.B. | 00000790 50 6c 65 61 73 65 20 65 78 63 75 73 65 20 6d 79 |Please excuse my| 000007a0 20 74 6f 74 61 6c 6c 79 20 75 6e 63 6f 6d 6d 65 | totally uncomme| 000007b0 6e 74 65 64 20 61 6e 64 20 75 6e 72 65 61 64 61 |nted and unreada| 000007c0 62 6c 65 20 42 61 73 69 63 2e 0a 20 20 0a 20 20 |ble Basic.. . | 000007d0 4c 69 6e 65 73 20 75 70 20 74 6f 20 34 33 30 20 |Lines up to 430 | 000007e0 61 72 65 20 66 6f 72 20 73 65 74 74 69 6e 67 20 |are for setting | 000007f0 75 70 20 61 6e 64 20 6d 61 69 6e 6c 79 20 69 6e |up and mainly in| 00000800 76 6f 6c 76 65 20 67 65 74 74 69 6e 67 20 74 68 |volve getting th| 00000810 65 20 62 72 75 73 68 20 73 70 72 69 74 65 73 20 |e brush sprites | 00000820 73 6f 72 74 65 64 20 6f 75 74 2c 20 74 68 65 20 |sorted out, the | 00000830 6d 61 69 6e 20 6c 6f 6f 70 20 69 73 20 6c 69 6e |main loop is lin| 00000840 65 73 20 34 33 30 20 74 6f 20 35 31 30 2e 0a 20 |es 430 to 510.. | 00000850 20 0a 20 20 78 25 20 69 73 20 74 68 65 20 63 75 | . x% is the cu| 00000860 72 72 65 6e 74 20 78 20 70 6f 73 69 74 69 6f 6e |rrent x position| 00000870 20 6f 66 20 74 68 65 20 6d 6f 75 73 65 2c 20 78 | of the mouse, x| 00000880 32 25 20 69 73 20 74 68 65 20 70 72 65 76 69 6f |2% is the previo| 00000890 75 73 20 78 20 70 6f 73 69 74 69 6f 6e 20 6f 66 |us x position of| 000008a0 20 74 68 65 20 6d 6f 75 73 65 2e 20 28 53 69 6d | the mouse. (Sim| 000008b0 69 6c 61 72 6c 79 20 66 6f 72 20 79 25 20 61 6e |ilarly for y% an| 000008c0 64 20 79 32 25 29 2e 0a 20 20 0a 20 20 57 68 65 |d y2%).. . Whe| 000008d0 6e 20 64 72 61 77 69 6e 67 2c 20 53 68 61 64 65 |n drawing, Shade| 000008e0 20 74 61 6b 65 73 20 70 6f 69 6e 74 73 20 74 77 | takes points tw| 000008f0 6f 20 61 74 20 61 20 74 69 6d 65 2c 20 61 6e 64 |o at a time, and| 00000900 20 69 6e 74 65 72 70 6f 6c 61 74 65 73 20 62 65 | interpolates be| 00000910 74 77 65 65 6e 20 74 68 65 6d 20 74 6f 20 63 72 |tween them to cr| 00000920 65 61 74 65 20 61 20 63 6f 6e 74 69 6e 75 6f 75 |eate a continuou| 00000930 73 20 6c 69 6e 65 20 2d 20 74 68 69 73 20 69 73 |s line - this is| 00000940 20 64 6f 6e 65 20 62 79 20 50 52 4f 43 64 72 61 | done by PROCdra| 00000950 77 5f 61 63 72 6f 73 73 20 61 6e 64 20 50 52 4f |w_across and PRO| 00000960 43 64 72 61 77 5f 75 70 2e 20 54 68 69 73 20 69 |Cdraw_up. This i| 00000970 73 20 64 6f 6e 65 20 77 69 74 68 20 72 65 73 70 |s done with resp| 00000980 65 63 74 20 74 6f 20 65 69 74 68 65 72 20 74 68 |ect to either th| 00000990 65 20 68 6f 72 69 7a 6f 6e 74 61 6c 20 6f 72 20 |e horizontal or | 000009a0 74 68 65 20 76 65 72 74 69 63 61 6c 20 64 65 70 |the vertical dep| 000009b0 65 6e 64 69 6e 67 20 6f 6e 20 77 68 65 74 68 65 |ending on whethe| 000009c0 72 20 74 68 65 20 67 72 61 64 69 65 6e 74 20 6f |r the gradient o| 000009d0 66 20 74 68 65 20 6c 69 6e 65 20 69 73 20 67 72 |f the line is gr| 000009e0 65 61 74 65 72 20 6f 72 20 6c 65 73 73 20 74 68 |eater or less th| 000009f0 61 6e 20 31 20 28 64 65 63 69 64 65 64 20 62 79 |an 1 (decided by| 00000a00 20 50 52 4f 43 64 72 61 77 29 2e 0a 20 20 46 6f | PROCdraw).. Fo| 00000a10 72 20 65 61 63 68 20 70 6f 73 69 74 69 6f 6e 20 |r each position | 00000a20 6f 6e 20 74 68 65 20 6c 69 6e 65 2c 20 74 68 65 |on the line, the| 00000a30 20 61 73 73 65 6d 62 6c 65 72 20 70 6c 6f 74 20 | assembler plot | 00000a40 72 6f 75 74 69 6e 65 20 69 73 20 63 61 6c 6c 65 |routine is calle| 00000a50 64 2e 20 52 65 67 69 73 74 65 72 73 20 61 74 20 |d. Registers at | 00000a60 73 74 61 72 74 20 61 72 65 20 61 73 20 66 6f 6c |start are as fol| 00000a70 6c 6f 77 73 3a 0a 20 20 52 30 20 2d 20 73 74 61 |lows:. R0 - sta| 00000a80 72 74 20 61 64 64 72 65 73 73 20 6f 66 20 73 63 |rt address of sc| 00000a90 72 65 65 6e 20 6d 65 6d 6f 72 79 0a 20 20 52 31 |reen memory. R1| 00000aa0 20 2d 20 78 20 6c 6f 63 61 74 69 6f 6e 20 6f 66 | - x location of| 00000ab0 20 70 6c 6f 74 0a 20 20 52 32 20 2d 20 79 20 6c | plot. R2 - y l| 00000ac0 6f 63 61 74 69 6f 6e 20 6f 66 20 70 6c 6f 74 0a |ocation of plot.| 00000ad0 20 20 52 33 20 2d 20 77 69 64 74 68 20 6f 66 20 | R3 - width of | 00000ae0 70 6c 6f 74 0a 20 20 52 34 20 2d 20 68 65 69 67 |plot. R4 - heig| 00000af0 68 74 20 6f 66 20 70 6c 6f 74 0a 20 20 20 20 28 |ht of plot. (| 00000b00 4f 72 69 67 69 6e 61 6c 6c 79 20 64 69 66 66 65 |Originally diffe| 00000b10 72 65 6e 74 20 73 69 7a 65 64 20 62 72 75 73 68 |rent sized brush| 00000b20 65 73 20 77 65 72 65 20 70 6c 61 6e 6e 65 64 2c |es were planned,| 00000b30 20 68 6f 77 65 76 65 72 20 49 20 6e 65 76 65 72 | however I never| 00000b40 20 67 6f 74 20 72 6f 75 6e 64 20 74 6f 20 69 6d | got round to im| 00000b50 70 6c 65 6d 65 6e 74 69 6e 67 20 74 68 69 73 29 |plementing this)| 00000b60 0a 20 20 52 35 20 2d 20 73 74 61 72 74 20 61 64 |. R5 - start ad| 00000b70 64 72 65 73 73 20 6f 66 20 6d 61 73 6b 2c 20 67 |dress of mask, g| 00000b80 65 6e 65 72 61 74 65 64 20 66 72 6f 6d 20 73 70 |enerated from sp| 00000b90 72 69 74 65 20 64 61 74 61 20 77 68 65 6e 20 70 |rite data when p| 00000ba0 72 6f 67 72 61 6d 20 69 73 20 73 74 61 72 74 65 |rogram is starte| 00000bb0 64 20 75 70 20 62 79 20 50 52 4f 43 73 65 74 75 |d up by PROCsetu| 00000bc0 70 5f 70 69 78 74 61 62 6c 65 0a 20 20 52 36 20 |p_pixtable. R6 | 00000bd0 2d 20 61 64 64 72 65 73 73 20 6f 66 20 62 6c 6f |- address of blo| 00000be0 63 6b 20 63 6f 6e 74 61 69 6e 69 6e 67 20 63 6f |ck containing co| 00000bf0 6c 6f 75 72 20 69 6e 66 6f 72 6d 61 74 69 6f 6e |lour information| 00000c00 20 28 63 6f 6c 73 25 29 0a 20 20 52 37 20 2d 20 | (cols%). R7 - | 00000c10 62 72 75 73 68 20 74 79 70 65 2e 0a 20 20 4c 69 |brush type.. Li| 00000c20 6e 65 73 20 39 30 30 20 74 6f 20 31 30 35 30 20 |nes 900 to 1050 | 00000c30 64 6f 20 73 65 74 75 70 2c 20 74 72 61 6e 73 6c |do setup, transl| 00000c40 61 74 65 20 74 68 65 20 63 6f 2d 6f 72 64 69 6e |ate the co-ordin| 00000c50 61 74 65 73 20 69 6e 66 6f 72 6d 61 74 69 6f 6e |ates information| 00000c60 20 69 6e 74 6f 20 61 64 64 72 65 73 73 65 73 20 | into addresses | 00000c70 74 6f 20 73 74 61 72 74 20 61 6e 64 20 65 6e 64 |to start and end| 00000c80 20 74 68 65 20 70 6c 6f 74 3b 20 74 68 65 20 72 | the plot; the r| 00000c90 65 6d 61 69 6e 64 65 72 20 69 73 20 74 68 65 20 |emainder is the | 00000ca0 61 63 74 75 61 6c 20 70 6c 6f 74 20 63 6f 64 65 |actual plot code| 00000cb0 2e 20 54 68 69 73 20 73 65 63 74 69 6f 6e 20 67 |. This section g| 00000cc0 6f 65 73 20 74 68 72 6f 75 67 68 20 65 61 63 68 |oes through each| 00000cd0 20 6d 65 6d 6f 72 79 20 6c 6f 63 61 74 69 6f 6e | memory location| 00000ce0 20 74 6f 20 62 65 20 63 68 61 6e 67 65 64 2c 20 | to be changed, | 00000cf0 63 68 65 63 6b 73 20 69 66 20 69 74 20 69 73 6e |checks if it isn| 00000d00 27 74 20 6d 61 73 6b 65 64 20 6f 75 74 2c 20 61 |'t masked out, a| 00000d10 6e 64 20 69 66 20 69 74 20 69 73 6e 27 74 2c 20 |nd if it isn't, | 00000d20 73 70 6c 69 74 73 20 6f 75 74 20 74 68 65 20 63 |splits out the c| 00000d30 6f 6c 6f 75 72 20 63 6f 6d 70 6f 6e 65 6e 74 73 |olour components| 00000d40 20 61 6e 64 20 61 64 64 73 20 28 6f 72 20 73 75 | and adds (or su| 00000d50 62 74 72 61 63 74 73 29 20 69 6e 20 74 68 65 20 |btracts) in the | 00000d60 63 6f 6c 6f 75 72 20 73 68 69 66 74 2e 0a 20 20 |colour shift.. | 00000d70 44 75 72 69 6e 67 20 74 68 65 20 70 6c 6f 74 74 |During the plott| 00000d80 69 6e 67 20 70 72 6f 63 65 73 73 2c 20 72 65 67 |ing process, reg| 00000d90 69 73 74 65 72 73 20 61 72 65 20 75 73 65 64 20 |isters are used | 00000da0 61 73 20 66 6f 6c 6c 6f 77 73 3a 0a 20 20 28 69 |as follows:. (i| 00000db0 66 20 49 20 72 65 6d 65 6d 62 65 72 20 63 6f 72 |f I remember cor| 00000dc0 72 65 63 74 6c 79 21 29 0a 20 20 52 31 20 2d 20 |rectly!). R1 - | 00000dd0 73 68 69 66 74 20 66 6f 72 20 63 75 72 72 65 6e |shift for curren| 00000de0 74 20 63 6f 6c 6f 75 72 20 28 72 65 64 2f 67 72 |t colour (red/gr| 00000df0 65 65 6e 2f 62 6c 75 65 29 0a 20 20 52 32 20 2d |een/blue). R2 -| 00000e00 20 38 2d 62 69 74 20 76 61 6c 75 65 20 6f 66 20 | 8-bit value of | 00000e10 63 75 72 72 65 6e 74 20 63 6f 6c 6f 75 72 20 63 |current colour c| 00000e20 6f 6d 70 6f 6e 65 6e 74 20 6f 66 20 70 69 78 65 |omponent of pixe| 00000e30 6c 0a 20 20 52 36 20 2d 20 61 64 64 72 65 73 73 |l. R6 - address| 00000e40 20 6f 66 20 63 75 72 72 65 6e 74 20 70 6f 73 69 | of current posi| 00000e50 74 69 6f 6e 20 69 6e 20 63 6f 6c 6f 75 72 20 69 |tion in colour i| 00000e60 6e 66 6f 20 62 6c 6f 63 6b 0a 20 20 52 37 20 2d |nfo block. R7 -| 00000e70 20 62 69 74 20 6f 66 66 73 65 74 20 66 72 6f 6d | bit offset from| 00000e80 20 30 20 6f 66 20 63 75 72 72 65 6e 74 20 63 6f | 0 of current co| 00000e90 6c 6f 75 72 20 69 6e 20 70 69 78 65 6c 20 64 61 |lour in pixel da| 00000ea0 74 61 0a 20 20 52 38 20 2d 20 6d 61 73 6b 20 66 |ta. R8 - mask f| 00000eb0 6f 72 20 63 75 72 72 65 6e 74 20 70 69 78 65 6c |or current pixel| 00000ec0 20 6c 6f 61 64 65 64 20 68 65 72 65 0a 20 20 52 | loaded here. R| 00000ed0 39 20 2d 20 73 74 61 72 74 20 61 64 64 72 65 73 |9 - start addres| 00000ee0 73 20 6f 66 20 70 6f 73 69 74 69 6f 6e 20 69 6e |s of position in| 00000ef0 20 70 6c 6f 74 2c 20 69 6e 63 72 65 6d 65 6e 74 | plot, increment| 00000f00 65 64 20 77 69 74 68 20 65 61 63 68 20 70 69 78 |ed with each pix| 00000f10 65 6c 0a 20 20 52 31 30 20 2d 20 65 6e 64 20 61 |el. R10 - end a| 00000f20 64 64 72 65 73 73 20 6f 66 20 70 6c 6f 74 0a 20 |ddress of plot. | 00000f30 20 52 31 31 20 2d 20 63 6f 6c 6f 75 72 20 64 61 | R11 - colour da| 00000f40 74 61 20 6f 66 20 63 75 72 72 65 6e 74 20 70 69 |ta of current pi| 00000f50 78 65 6c 0a 20 20 52 31 32 20 2d 20 65 6e 64 20 |xel. R12 - end | 00000f60 61 64 64 72 65 73 73 20 6f 66 20 63 75 72 72 65 |address of curre| 00000f70 6e 74 20 6c 69 6e 65 20 74 6f 20 70 6c 6f 74 0a |nt line to plot.| 00000f80 20 20 49 74 27 73 20 70 72 6f 62 61 62 6c 79 20 | It's probably | 00000f90 70 6f 73 73 69 62 6c 65 20 74 6f 20 63 6f 64 65 |possible to code| 00000fa0 20 61 6c 6c 20 6f 66 20 74 68 69 73 20 6d 75 63 | all of this muc| 00000fb0 68 20 6d 6f 72 65 20 73 69 6d 70 6c 79 2c 20 62 |h more simply, b| 00000fc0 75 74 20 49 20 63 6f 75 6c 64 6e 27 74 20 77 6f |ut I couldn't wo| 00000fd0 72 6b 20 6f 75 74 20 68 6f 77 21 0a 0a 20 20 4c |rk out how!.. L| 00000fe0 69 6e 65 73 20 31 34 39 30 20 6f 6e 77 61 72 64 |ines 1490 onward| 00000ff0 73 20 61 72 65 20 74 68 65 20 75 73 65 72 20 69 |s are the user i| 00001000 6e 74 65 72 66 61 63 65 2c 20 74 68 69 73 20 73 |nterface, this s| 00001010 68 6f 75 6c 64 20 62 65 20 66 61 69 72 6c 79 20 |hould be fairly | 00001020 73 65 6c 66 2d 65 78 70 6c 61 6e 61 74 6f 72 79 |self-explanatory| 00001030 3b 20 61 20 75 73 65 72 20 73 70 72 69 74 65 20 |; a user sprite | 00001040 61 72 65 61 2c 20 73 74 61 72 74 69 6e 67 20 61 |area, starting a| 00001050 74 20 73 70 72 69 74 65 25 2c 20 69 73 20 75 73 |t sprite%, is us| 00001060 65 64 20 74 6f 20 73 74 6f 72 65 20 74 68 65 20 |ed to store the | 00001070 63 75 72 72 65 6e 74 20 70 69 63 74 75 72 65 20 |current picture | 00001080 77 68 69 6c 65 20 74 68 65 20 6d 65 6e 75 20 69 |while the menu i| 00001090 73 20 62 65 69 6e 67 20 75 73 65 64 2e 20 50 52 |s being used. PR| 000010a0 4f 43 73 65 74 63 6f 6c 73 20 6d 61 6b 65 73 20 |OCsetcols makes | 000010b0 73 75 72 65 20 74 68 61 74 20 74 68 65 20 74 65 |sure that the te| 000010c0 78 74 20 69 73 20 69 6e 20 61 20 72 65 61 64 61 |xt is in a reada| 000010d0 62 6c 65 20 63 6f 6c 6f 75 72 20 6e 6f 20 6d 61 |ble colour no ma| 000010e0 74 74 65 72 20 77 68 61 74 20 74 68 65 20 62 61 |tter what the ba| 000010f0 63 6b 67 72 6f 75 6e 64 20 63 6f 6c 6f 75 72 20 |ckground colour | 00001100 69 73 21 |is!| 00001103
.