home *** CD-ROM | disk | FTP | other *** search
- 'Starting to programme? Jump in the deep end and write your own art
- 'package! This may help a little. Although there are hundreds of AMOS
- 'commands we only use around 30 here. It is neither efficient nor elegant
- 'but it should be readable and may help the odd penny to drop.
- '
- 'Absolute beginners should ensure they understand the use of loops. Try
- 'writing a programme to print the numbers 1 to 10 on the screen. We might
- 'write - Print 1 : Print 2 : Print 3 : Etc. This would work but we have to
- 'do all the tricky headwork; working out what the next number is! Better to
- 'get the computer to do it for you - that's what you paid for! So we set
- 'up a variable called NUMBER. Think of a variable as a named box in which we
- 'place a value. We use a loop to INCrement and print the value of NUMBER.
- 'The instructions inside a loop are carried out over and over again until
- 'something happens (that we have planned!) that lets us jump out of the loop.
- 'You are the variable NUMBER! Work through these loops & see how you change!
- '
- ' NUMBER = 0 NUMBER = 1
- ' Do Do
- ' Inc NUMBER Try this one -> Print NUMBER
- ' Print NUMBER What happened? Inc NUMBER
- ' Exit If NUMBER = 10 Exit If NUMBER = 10
- ' Loop Loop
- '
- ' Do/Loop structures are crude; we have to tell them what to do and when
- ' to Exit etc. We could try Repeat/Until and While/Wend loops...
- ' the symbol < translates as "is less than"
- '
- ' NUMBER = 0 NUMBER = 0
- ' Repeat Checks value here -> While NUMBER < 10
- ' Inc NUMBER Inc NUMBER
- ' Print NUMBER Print NUMBER
- ' Until NUMBER = 10 <- Checks value here Wend
- '
- ' Did you spot the difference? It still looks like hard work to me!
- ' The For/Next loop will do all the work for us. How lazy can we get?
- '
- ' For NUMBER = 1 To 10
- ' Print NUMBER
- ' Next NUMBER
- '
- ' So use the right loop for the job you are doing and save yourself time,
- ' effort, memory and disc space! Be as lazy as you can! And now....
- '
- ' ==============================================
- ' = A Bare Bones Drawing Programme. =
- ' = by Duncan Moran =
- ' ==============================================
- '
- ' Use MERGE ASCII (press right mouse button) to load into your AMOS editor
- '
- ' Just tart it up a bit. Add an amusing & colourful cartoon like
- ' character and a jingly jangly tune and sell the lot for £25!!!!
- '
- '
- '
- ' Anything written over here with a
- ' <= <= <= <= <= ' at the start of the line is for you to read.
- ' The computer only needs the lines starting on the left
- ' without a ' at the start.
- '
- '
- '
- ' Set global variables for use throughout the programme
- '
- ' Variable Names What they contain
- ' -------------- -----------------
- ' XSTARTPOS & YSTARTPOS = X & Y Start positions
- ' XPOSNOW & YPOSNOW = their position now
- ' MZ = Number of the zone on the
- ' screen at which the mouse
- ' is pointing = Mouse Zone
- ' -------------------- --------------------
- '
- '
- Global XSTARTPOS,YSTARTPOS,XPOSNOW,YPOSNOW,MZ
- '
- ' Start here.....
- '
- SET_IT_UP
- '
- ' The Main Loop
- Do
- WHICH_BUTTON
- Loop
- '
- '
- ' That's all there is to it! Pretty lazy eh!
- ' Worth £25 of anyones money don't you think?
- '
- '
- ' These are the procedures that do all the work.
- '
- Procedure SET_IT_UP
- ' N.B. Computers start counting from zero.
- '
- ' Open screen number 0
- ' Pictures on a screen are made up from dots which
- ' are refered to as Pixels - Picture elements.
- ' Make our screen 320 pixels wide by 200 high
- ' give it 2 colours and make it low resolution.
- '
- ' < 320 >
- ' ___________________ The character in the middle
- ' - : : is 160 across (X direction)
- ' Rows go - : : and 100 down (Y direction)
- ' across - : ¤ : 200
- ' - : :
- ' -------------------
- ' ||||||||
- ' Columns go up & down
- '
- ' Think how far along the R ow and then how far down the C olumn
- ' Think R hubarb and C ustard! Hope this is not too technical!
- '
- '
- ' Nurse! The......
- '
- Screen Open 0,320,200,2,Lowres
- '
- '
- ' Screen 1 will be the one we draw on
- ' Screen 0 will be out of sight and used to
- ' hold a copy of our drawing ready to be undone.
- '
- Screen Open 1,320,200,2,Lowres
- '
- ' Set colour 0 to white and colour 1 to black
- ' Colours are made from R ed, G reen and B lue parts.
- ' We tell the computer about colours like this -> $RGB.
- ' Each colour can have a value from 0 to 15 denoted by
- ' 0 1 2 3 4 5 6 7 8 9 A B C D E F
- ' $FFF represents maximum red, blue and green = white.
- ' $000 represents NO red, blue or green which = black.
- ' AMOS will not show leading 0's so this will be $0
- Palette $FFF,$000
- '
- ' Open a narrow (32 rows) toolbox screen
- Screen Open 2,320,32,2,Lowres
- '
- ' set toolbox colours to $FF0 and $00F
- ' $FF0 = maximum Red and Green No Blue = yellow
- ' $00F = NO Red or Green = just Blue.
- '
- ' Compare with your photographic negatives.
- '
- Palette $FF0,$F
- '
- ' Call the procedure to make the buttons.
- SET_UP_BUTTONS
- '
- End Proc
- '
- Procedure SET_UP_BUTTONS
- '
- ' Set the Ink colour to colour 1 (blue)
- ' and the Paper colour to colour 0 (yellow)
- Ink 1,0
- ' The variables UPPERLEFT, BOTTOMRIGHT & COUNTER are Local
- ' Variables they have no value outside this procedure not
- ' like the Global variables which hold a value throughout.
- ' Top Left corner starts at position 1 (measured in Pixels)
- UPPERLEFT=1
- ' Bottom Right is at 53
- BOTTOMRIGHT=53
- ' Make space to remember where the six buttons are
- Reserve Zone 6
- '
- ' For/Next loop. Loops for specified number of times.
- ' Loop 6 times. Each loop draws a box on the screen
- ' and sets the zone to the same size. The value of COUNTER
- ' starts as 1. It increases on each loop until it
- ' reaches 7 which is too high & so we drop out of the loop.
- '
- For COUNTER=1 To 6
- '
- ' Draw a box/button from Top Left to Bottom Right
- ' The top line of button is always 5 rows down and the
- ' bottom line will be on the 25th row. Constant values.
- Box UPPERLEFT,5 To BOTTOMRIGHT,25
- '
- ' Zone number = current value of COUNTER (1 to 6)
- ' Set dimensions to the same as those of the box.
- Set Zone COUNTER,UPPERLEFT,5 To BOTTOMRIGHT,25
- '
- ' Read the next item from the DATA list below.
- ' Variable names with a $ on the end will hold a string
- ' of characters contained within "inverted commas".
- ' These are known as String Variables.
- Read WORD$
- '
- ' Use UPPERLEFT to work out where to stick it
- ' on the 13th row.
- Text UPPERLEFT+2,13,WORD$
- '
- ' Shove both corners along 53 places
- ' N.B. Use a colon : to seperate instructions on the
- ' same line
- Add UPPERLEFT,53 : Add BOTTOMRIGHT,53
- '
- ' If COUNTER is not finished do next loop
- Next COUNTER
- '
- ' Write a couple more words to finish it off
- Text 12,22," Exit" : Text 178,22,"Hand"
- '
- ' The DATA list read from within the loop
- Data "Wipe","Undo","Line","Free-","Square","Circle"
- '
- End Proc
- '
- Procedure WHICH_BUTTON
- ' Make the toolbox screen the one we are interested in
- Screen 2
- '
- ' Keep checking which zone the mouse is pointing at
- ' until mouse is clicked. MZ will then hold that zone's
- ' number (1 to 6). MK will tell which Mouse button was
- ' pressed Left = 1 Right = 2 Both = 3
- '
- ' Repeat/Until loop. Loops until a condition is met.
- Repeat
- MZ=Mouse Zone
- MK=Mouse Key
- Until Mouse Click
-
- '
- ' If you're in zone 1 and pressed the right button then bye!
- If MZ=1 and MK=2 Then Stop
- '
- ' If it's NOT Undo then copy all of drawing on to screen 0
- If Not MZ=2 Then Screen Copy 1 To 0
- '
- ' Make the drawing screen the current screen and....
- Screen 1
- ' ....go and do whatever MZ was pointing at (1 to 6)
- On MZ Proc WIPE,UNDO,STRAIGHT,F_HAND,SQUARE,CIRCUS
- '
- ' Finished here so jump back to Main Loop.
- End Proc
- '
- '
- '
- ' These are the procedures that are called by selecting
- ' one of the buttons on screen
- '
- Procedure WIPE
- ' Clear the Screen
- Cls
- End Proc
- '
- Procedure UNDO
- ' Copy screen 0 back to screen 1
- ' You will not have copied the last drawing operation
- ' if you clicked on Undo (MZ=2)
- Screen Copy 0 To 1
- End Proc
- '
- ' N.B. Circle, Line & Free etc. are words used by AMOS
- ' so they can not be used as procedure names.
- '
- Procedure STRAIGHT
- ' Call procedure to switch button on
- SWITCHEROO
- '
- ' Call procedure to find the start position
- MOUSEY_MOUSEY
- '
- ' Gr aphic Writing changes the way things are drawn
- ' on the screen. The number can range from 0 to 7.
- '
- ' Change this to Gr Writing 1 and make nice patterns!
- Gr Writing 2
- '
- ' Keep switching between ink colours 0 & 1, drawing a line
- ' between start & current position until mouse is clicked.
- '
- ' Do/Loop. Loops continuosly until exit condition is met.
- Do
- Ink 0
- XPOSNOW=X Screen(X Mouse)
- YPOSNOW=Y Screen(Y Mouse)
- Draw XSTARTPOS,YSTARTPOS To XPOSNOW,YPOSNOW
- Ink 1
- Draw XSTARTPOS,YSTARTPOS To XPOSNOW,YPOSNOW
- '
- ' Jump out of loop if mouse button pressed.
- Exit If Mouse Click
- '
- Loop
- '
- ' draw line in last position
- Gr Writing 1
- Draw XSTARTPOS,YSTARTPOS To XPOSNOW,YPOSNOW
- '
- ' Switch button off
- SWITCHEROO
- End Proc
- '
- Procedure F_HAND
- ' Most of the drawing procedures are much alike
- ' so see the STRAIGHT procedure for details.
- '
- SWITCHEROO
- MOUSEY_MOUSEY
- '
- ' Keep drawing while a mouse key is pressed down
- ' Left button = 1 Right = 2 Both together = 3
- '
- ' While/Wend loop. While a condition is true keep looping
- While Not Mouse Key=0
- XPOSNOW=X Screen(X Mouse)
- YPOSNOW=Y Screen(Y Mouse)
- Draw XSTARTPOS,YSTARTPOS To XPOSNOW,YPOSNOW
- XSTARTPOS=XPOSNOW : YSTARTPOS=YPOSNOW
- Wend
- '
- SWITCHEROO
- End Proc
- '
- Procedure SQUARE
- ' Most of the drawing procedures are much alike
- ' so see the STRAIGHT procedure for details.
- '
- SWITCHEROO
- MOUSEY_MOUSEY
- Gr Writing 2
- '
- ' create a box .........
- Do
- Ink 0
- XPOSNOW=X Screen(X Mouse)
- YPOSNOW=Y Screen(Y Mouse)
- Box XSTARTPOS,YSTARTPOS To XPOSNOW,YPOSNOW
- Ink 1
- Box XSTARTPOS,YSTARTPOS To XPOSNOW,YPOSNOW
- Exit If Mouse Click
- Loop
- '
- Gr Writing 1
- Box XSTARTPOS,YSTARTPOS To XPOSNOW,YPOSNOW
- '
- SWITCHEROO
- End Proc
- '
- Procedure CIRCUS
- ' Most of the drawing procedures are much alike
- ' so see the STRAIGHT procedure for details.
- '
- SWITCHEROO
- MOUSEY_MOUSEY
- Gr Writing 2
- '
- ' ...... and a circle/oval
- Do
- Ink 0
- XPOSNOW=X Screen(X Mouse)
- YPOSNOW=Y Screen(Y Mouse)
- '
- ' Calculate the two radii
- RADX=XPOSNOW-XSTARTPOS : RADY=YPOSNOW-YSTARTPOS
- '
- ' Change any negative values to positive
- ' i.e. ABSolute value of -7 is 7
- RADX = Abs(RADX) : RADY = Abs(RADY)
- '
- ' and we dont want zero either!
- If RADX=0 Then RADX=1
- If RADY=0 Then RADY=1
- '
- Ellipse XSTARTPOS,YSTARTPOS,RADX,RADY
- Ink 1
- Ellipse XSTARTPOS,YSTARTPOS,RADX,RADY
- Exit If Mouse Click
- Loop
- '
- Gr Writing 1
- Ellipse XSTARTPOS,YSTARTPOS,RADX,RADY
- '
- SWITCHEROO
- End Proc
- '
- Procedure MOUSEY_MOUSEY
- '
- ' Wait for a mouse click record x & y start positions.
- ' The Mouse uses Hardware Coordinates so convert
- ' these with the X/Y Screen function to find the
- ' position on the screen.
- Repeat
- XSTARTPOS=X Screen(X Mouse)
- YSTARTPOS=Y Screen(Y Mouse)
- Until Mouse Click
- '
- ' Return to where you came from with the new XSTARTPOS & YSTARTPOS
- End Proc
- '
- Procedure SWITCHEROO
- ' Switch the colours when selecting a button.
- ' Switch them back again when done.
- Screen 2
- Gr Writing 2
- '
- ' Work out the top left corner of the button.
- ' * means multiply.
- UPPERLEFT=((MZ-1)*53)
- '
- ' and the bottom right one.
- BOTTOMRIGHT=UPPERLEFT+53
- '
- ' Draw a bar over button to reverse the colours
- Bar UPPERLEFT,5 To BOTTOMRIGHT,25
- '
- Gr Writing 1
- Screen 1
- End Proc
- '
- '
- ' That's it for now!
- ' Next time more tools & colours & even much more betterer too!
-
