UDG in Assembly

Comments

• Arjun

  August 2012 edited August 2012

  In the case of the spectrum, there is no dedicated sprite hardware or toolset to manage them. Instead, you have the CPU and the entire RAM at your disposal to use it as you see fit.
  
  So, while creating a sprite from bit patterns isn't particularly difficult (quite similar to how you do it above actually), moving the sprites around is a bit more complicated because of the way the speccy's display is arranged.
  
  You could look around in the development section of this forum to see various threads on the very same topic. Or you could have a look at some of the tutorials in the Chuntey blog (see my sig) regarding sprite handling. There are also *tons* of books in the archive that you can download and refer to at your leisure on the subject.
  
  This forums is of course always at your disposal in case you need any specific tips and help in this regard. :)

  Zero - A modern Spectrum emulator for Windows.
  Bytes:Chuntey - Spectrum tech blog.
• chev

  August 2012 edited August 2012

  Looks like you're talking about sprites rather than UDGs. The Spectrum doesn't have hardware sprites, but it does have the rather excellent splib sprite library for z88dk. This probably isn't the most up to date link, but it should get you started: http://www.timexsinclair.org/alvin/

  zx.itch.io
• Ralf

  August 2012 edited August 2012

  UDG is a concept from Spectrum implementation of Basic. In assembler you theoretically could call the ROM routines dealing with UDG (they are the same routines used to print letters) but forget it :) It's always better to write something your own than to rely on slow and limited ROM procedures.
  
  Some simplest "sprite"

  LD HL,16000
   LD DE,16384
   LD B,8
  Loop:
   LD A,(HL)
   LD (DE),A
   INC HL
   INC D
   DJNZ Loop
   RET
  

  
  It will copy from the ROM graphics making the "P" letter but you can point to any other graphics.
  
  All sprite drawing in Spectrum is copying data to screen memory. There is not any other way.
  
  This example is sprite drawing at "equal" position - fitting it precisely into a grid 32x24, a bit similar to text mode. Drawing just anywhere is much harder and you'll have to learn the Spectrum screen organisation. It's not easy for beginner but don't give up and you'll eventually get it :)
• Battle Bunny

  August 2012 edited August 2012

  Here's some TAPs (with instructions) of useful magazine type-in sprite routines from TTFn.
  
  Star Tip 7 (Sprite Moving), Raffaelle Cecco, Your Sinclair, Dec'87
  Sprite Designer, Toni Baker, Your Spectrum, Dec'84
  Sprite Designer, Chris Wood, Your Spectrum, Oct'85
  Sprite Creator, Roger Allen, Sinclair Programs, Dec'84
  Sprite Editor, Robert Newman, Your Computer, Jun'85
  Sprite Designer, Dom Early, Your Sinclair, Apr'88
  Sprite Editor, Simon Owen, Your Sinclair, Aug'88
  Sprite Grabber, Steve Anderson, Your Sinclair, Nov'92
• chev

  August 2012 edited August 2012

  Battle Bunny wrote: »

  Here's some TAPs (with instructions) of useful magazine type-in sprite routines...

  
  Well knowing Simon Owen's work that one might suit the OP, but really unless you want to write your own routine from scratch there's no good reason not to use Alvin's splib.

  zx.itch.io