how to calculate pfpixel coordinates (playfield 32 rows)

[Erik Zimmermann]

My playfield has 32 rows. How do I calculate the coordinates for pfpixel? 

 

_paint_block
  e=((player1x) / : f=(player1y) / 16
  pfpixel  e f on

a1.bas

[+Random Terrain]

Move joystick to draw. Hold fire button to erase while moving joystick. Press reset switch to clear the screen.

 

Here's the .bas file:

a1_2022y_02m_02d_1220t.bas

 

Here's the .bin file to use with your favorite emulator:

a1_2022y_02m_02d_1220t.bin

[Erik Zimmermann]

THANK YOU !!!! VERY COOL. 

[+Gemintronic]

I shouldn't be asking this, but.. I've gotten it wrong by trying to figure out the maths myself in the past.

 

I see this block of code that applies for 32 rows:

   ;***************************************************************
   ;
   ;  Playfield drawing and erasing.
   ;
   ;```````````````````````````````````````````````````````````````
   ;  Converts sprite coordinates to playfield coordinates.
   ;
   temp5 = (player1x-13)/4

   temp6 = (player1y)/3

 

What is the version for regular old (non SARA RAM) 12 rows?

 

 

[+Random Terrain]

14 minutes ago, Gemintronic said:

I shouldn't be asking this, but.. I've gotten it wrong by trying to figure out the maths myself in the past.

 

I see this block of code that applies for 32 rows:

   ;***************************************************************
   ;
   ;  Playfield drawing and erasing.
   ;
   ;```````````````````````````````````````````````````````````````
   ;  Converts sprite coordinates to playfield coordinates.
   ;
   temp5 = (player1x-13)/4

   temp6 = (player1y)/3

 

What is the version for regular old (non SARA RAM) 12 rows?

 

 

 

I think I already have it figured out in the Collision Prevention example programs:

 

https://www.randomterrain.com/atari-2600-memories-batari-basic-commands.html#expro_collision

 

It's something like this:

   temp5 = (player0x-10)/4

   temp6 = (player0y-9)/8

 

But the numbers you subtract usually have to change depending on the sprite and what you want it to do.

[Erik Zimmermann]

Hello,

 

In this example "ex_sprite_with_missile.bas", i want to fire a Missile.  Paint blocks on free place or
erase a exist block on the playfield.
How exactly do I calculate the coordinates for the missile

 

Bye

Erik

ex_sprite_with_missile.bas

[+Random Terrain]

Have you looked at these example programs:

 

https://www.randomterrain.com/atari-2600-memories-batari-basic-commands.html#ex_shoot_pfpixel

 

https://www.randomterrain.com/atari-2600-memories-batari-basic-commands.html#ex_sprite_missile_pfpixel_destruction

 

 

More example programs are listed here:

 

https://www.randomterrain.com/atari-2600-memories-batari-basic-commands.html#example_programs