Paddles and Batari Basic

[toiletunes]

I'm having trouble trying to figure out how to use a paddle to change the position of player0. Here's some simple code for reference- what am I missing?

 

set kernel_options no_blank_lines readpaddle

COLUP0 = 40

player0:

%11111111

%01100110

end

player0x = 30

player0y = 50

COLUBK = 80

COLUPF = 20

playfield:

...............XX...............

X..............................X

...............XX...............

................................

X..............................X

.................XX.............

...............XX...............

X..............................X

...............XX...............

.............XX.................

X..............................X

end

mainloop

drawscreen

player0x = paddle

goto mainloop

 

(The Batari Basic command reference mentions something called currentpaddle, but I get an "unknown Keyword" error every time I add it to the lines above)

[+batari]

I'm having trouble trying to figure out how to use a paddle to change the position of player0. Here's some simple code for reference- what am I missing?

I tried your code and it works. The problem is probably that you haven't told the emulator that the binary uses the paddle, as it assumes joystick by default.

(The Batari Basic command reference mentions something called currentpaddle, but I get an "unknown Keyword" error every time I add it to the lines above)

currentpaddle is the paddle you are reading during the next frame. I couldn't repeat the error you describe with currentpaddle, but if you intend to use paddle 0, there's no need to change it.

[SeaGtGruff]

I tried your code and it works. The problem is probably that you haven't told the emulator that the binary uses the paddle, as it assumes joystick by default.

Darn, I was trying his code and couldn't get it to work, for the same reason-- I hadn't changed the game properties in Stella to say that a pair of paddles was plugged into the left controller port.

 

currentpaddle is the paddle you are reading during the next frame. I couldn't repeat the error you describe with currentpaddle, but if you intend to use paddle 0, there's no need to change it.

I think he was using the "currentpaddle" keyword by itself, rather than assigning a value to it, which does give the error message he mentioned. The HTML batari Basic manual doesn't give an example of how to use "currentpaddle." You use it as follows:

 

  rem *** to read paddle 0 and store its value in variable a
  currentpaddle = 0
  drawscreen
  a = paddle

  rem *** to read paddle 1 and store its value in variable b
  currentpaddle = 1
  drawscreen
  b = paddle

  rem *** to read paddle 2 and store its value in variable c
  currentpaddle = 2
  drawscreen
  c = paddle

  rem *** to read paddle 3 and store its value in variable d
  currentpaddle = 3
  drawscreen
  d = paddle

Note that "paddle" will return a number between 0 and 77 (I think), which isn't large enough to span the screen, since the players' horizontal positions range from 1 to 160. So if we multiply "paddle" by 2, and then add 1, we get a value between 1 and 155, which is better. But if the player is 8 pixels wide, and each pixel is 1 color clock wide, then we'd want a maximum horizontal position of 153, which would put the player's rightmost pixel at position 160. So here's a modified version of the code, to move player0 from the left side of the screen to the right side of the screen:

 

  include div_mul.asm
  rem *** Note that this modified code uses multiplication,
  rem *** so we have to include the div_mul.asm code.
  set kernel_options no_blank_lines readpaddle
  player0:
  %11111111
  %01100110
end
  player0x = 30
  player0y = 50
  COLUBK = 80
  COLUPF = 20
  playfield:
  ...............XX...............
  X..............................X
  ...............XX...............
  ................................
  X..............................X
  .................XX.............
  ...............XX...............
  X..............................X
  ...............XX...............
  .............XX.................
  X..............................X
end
  currentpaddle = 0
  rem *** Note that since all page-zero RAM is initialized to 0
  rem *** by batari Basic, currentpaddle will default to 0.
mainloop
  COLUP0 = 40
  rem *** Note that COLUP0 should be set within the display
  rem *** loop, because drawscreen changes it to the same
  rem *** value as scorecolor when the score is displayed.
  drawscreen
  player0x = 2 * paddle + 1
  if player0x > 153 then player0x = 153
  goto mainloop

After you compile the code, run it in the Stella emulator. But then you have to tell Stella to use the paddles, so press the TAB key, click the GAME PROPERTIES button, click the CONTROLLER tab, click the LEFT CONTROLLER dropdown box, click the PADDLES selection, click the OK button, and click the EXIT MENU button. Then press the BACKSLASH ("\") key (usually found just above the ENTER key), and click the RELOAD ROM button. Then you can move the player by moving the mouse back and forth, as long as the mouse pointer is over the game screen (if you're running Stella in a window).

 

If you want to use the keyboard to control the paddle-- say, to use the COMMA to move left (since it has the left-pointing LESS THAN symbol on it), and to use the PERIOD to move right (since it has the right-pointing GREATER THAN symbol on it)-- press the TAB key, click the INPUT SETTINGS button, scroll down and click PADDLE 1 DECREASE, click the MAP button, press the COMMA key, click PADDLE 1 INCREASE, click the MAP button, press the PERIOD key, click the OK button, and click the EXIT MENU button. Then press the BACKSLASH key and click RELOAD ROM again, and the COMMA and PERIOD keys will move the player-- but so will the mouse. To prevent the mouse from moving the paddle, press TAB, click INPUT SETTINGS, click VIRTUAL DEVICES, click the MOUSE IS PADDLE box to change it to something other than 0, click OK, click EXIT MENU, press BACKSLASH, and click RELOAD ROM.

 

Michael

[+Random Terrain]

I think he was using the "currentpaddle" keyword by itself, rather than assigning a value to it, which does give the error message he mentioned. The HTML batari Basic manual doesn't give an example of how to use "currentpaddle." You use it as follows:

 

  rem *** to read paddle 0 and store its value in variable a
  currentpaddle = 0
  drawscreen
  a = paddle

  rem *** to read paddle 1 and store its value in variable b
  currentpaddle = 1
  drawscreen
  b = paddle

  rem *** to read paddle 2 and store its value in variable c
  currentpaddle = 2
  drawscreen
  c = paddle

  rem *** to read paddle 3 and store its value in variable d
  currentpaddle = 3
  drawscreen
  d = paddle

Note that "paddle" will return a number between 0 and 77 (I think), which isn't large enough to span the screen, since the players' horizontal positions range from 1 to 160. So if we multiply "paddle" by 2, and then add 1, we get a value between 1 and 155, which is better. But if the player is 8 pixels wide, and each pixel is 1 color clock wide, then we'd want a maximum horizontal position of 153, which would put the player's rightmost pixel at position 160.

Is it OK if I put your example on both bB pages? My personal version and the official one?

[SeaGtGruff]

Is it OK if I put your example on both bB pages? My personal version and the official one?

By all means, help yourself! You're welcome to use any explanations or examples that I post-- as long as they don't contain any erroneous information, that is.

 

Michael

[+Random Terrain]

Is it OK if I put your example on both bB pages? My personal version and the official one?

By all means, help yourself! You're welcome to use any explanations or examples that I post-- as long as they don't contain any erroneous information, that is.

Thanks. I'll go add it right now before I forget.

[+Random Terrain]

SeaGtGruff, before I add it to the official page, can you check this to make sure I didn't mangle your example too horribly:

 

http://www.randomterrain.com/atari-2600-me...l#paddlereading

 

Thanks.

[+stephena]

After you compile the code, run it in the Stella emulator. But then you have to tell Stella to use the paddles, so press the TAB key, click the GAME PROPERTIES button, click the CONTROLLER tab, click the LEFT CONTROLLER dropdown box, click the PADDLES selection, click the OK button, and click the EXIT MENU button. Then press the BACKSLASH ("\") key (usually found just above the ENTER key), and click the RELOAD ROM button. Then you can move the player by moving the mouse back and forth, as long as the mouse pointer is over the game screen (if you're running Stella in a window).

I just wanted to add that if you're more accustomed to the commandline, you can start Stella with paddles as follows:

'stella -lc paddles ROMNAME'. Also, you can do a ROM reload by pressing 'Ctrl r', instead of going to the command menu (the one with the '/').

[toiletunes]

Thank you everyone, especially batari, SeaGtGruff, Random Terrain, and stephena. This community is so friendly and supportive, I wish I could move here!

Edited April 22, 2007 by toiletunes

[SeaGtGruff]

SeaGtGruff, before I add it to the official page, can you check this to make sure I didn't mangle your example too horribly:

Perhaps it might be good to use this slightly-revised example instead?

 

  rem *** read paddle 0, use it to position player0x across the screen
  currentpaddle = 0
  drawscreen
  player0x = 2 * paddle + 1 : if player0x > 153 then player0x = 153

  rem *** read paddle 1, use it to position player1x across the screen
  currentpaddle = 1
  drawscreen
  player1x = 2 * paddle + 1 : if player1x > 153 then player1x = 153

Michael

[+Random Terrain]

SeaGtGruff, before I add it to the official page, can you check this to make sure I didn't mangle your example too horribly:

Perhaps it might be good to use this slightly-revised example instead?

 

  rem *** read paddle 0, use it to position player0x across the screen
  currentpaddle = 0
  drawscreen
  player0x = 2 * paddle + 1 : if player0x > 153 then player0x = 153

  rem *** read paddle 1, use it to position player1x across the screen
  currentpaddle = 1
  drawscreen
  player1x = 2 * paddle + 1 : if player1x > 153 then player1x = 153

Thanks. Here is the latest change:

 

http://www.randomterrain.com/atari-2600-me...l#paddlereading

 

I'll add it to the official page now. Please let me know if you'd like the text above the example to be changed.