Re: A85: Sprite help...

To: assembly-85@lists.ticalc.org
Subject: Re: A85: Sprite help...
From: JayEll64@aol.com
Date: Mon, 5 Jul 1999 18:53:24 EDT
Delivered-To: assembly-85-outgoing@towerguard.unix.edu.sollentuna.se
Delivered-To: assembly-85@lists.ticalc.org
Reply-To: assembly-85@lists.ticalc.org

In a message dated 7/5/99 4:32:31 PM MDT, shunt@apex.net writes:
> 
>  Im trying DEPSERATELY to learn to use sprites in my progs. Ive learned to
>  move sprites on the screen byte by byte, that is, I can move a sprite over 
8
>  pixels at a time, and up and down any number or pixels i want, but I wanna
>  know how to
>  move them left and right a single pixel at a time.

Well...hmmm...someone else I know was trying to do this...  It's really 
pretty easy to do (sorry ;).

>  
>  
>  Ive tried several routines, checked my code and quadruple checked it, but
>  cant get any routines to work right.  Here is my code, using the newest
>  routine(i think) SDR by Jay L of Macross Software:

Okay (that's me ;).

>  
>  
>  #include "usgard.h"
>  
>          .org 0
>          .db "Test", 0
>  
>          call CLEARLCD
>  
>  
>          jr Draw

Here, you could just do a < call &Draw> and stick a < ret> at the end of the 
Draw routine.

>  
>  
>  
>  Wait:
>  
>          call GET_KEY
>          cp K_EXIT
>          jr nz, Wait
>          ret

Put a < halt> before the < call GET_KEY>; saves battery life.

>  
>  
>  
>  Draw:
>          ld hl, &Sprite
>          ld b, 9
>          ld c, 9

This could be optimized to < ld bc,9 * $100 + 9>.

>  
>  
>  
>  
>  
>  ;***this is the routine here:***
>  ;Sprite Drawing Routine (SDR): 8 Bit Normal Version
>  ;by JL
>  ;<JayEll64@aol.com>
>  ;
>  ;Inputs:
>  ; b=x coordinate
>  ; c=y coordinate
>  ; hl=pointer to sprite data
>  ;Outputs:
>  ; af=destroyed
>  ; bc=destroyed
>  ; de=destroyed
>  ; hl=pointer to byte after sprite
>  ; no other registers are changed
>  ;If you want to save those registers that are destroyed, push/pop them!
>  ;
>  ;Sprite data should be stored as follows:
>  ;.db (# rows/bytes/height of sprite)
>  ;.db (bitmap of sprite)
>  ;
>  
>  
>  
>  PutSprite:

Whoa, whoa, whoa...does *this* look like SDR8?!  I think you've put the 
header of my routine with PutSprite! ;)

>     push ix
>     push bc
>     push de
>     ld a,63              ;\
>     sub c                ; |63-y, so the drawing starts at the top
>     ld c,a               ;/
>     push hl
>     push hl
>     call FIND_PIXEL      ;hl has offset in viedo mem; a has bit^2
>     ld de,GRAPH_MEM      ;store into graph mem for virtual screen

Since DE is loaded with the graphics memory address, then the sprite will be 
drawn to the graphics memory.  Try changing this to < ld de,VIDEO_MEM>.

>     add hl,de
>     ex de,hl             ;de physical address in vid mem
>     pop hl               ;hl has sprite's beginning address again
>     ld b,8               ;ld b with width
>     ld c,8               ;ld c with height
>     push hl              ;(hl) has the graphics of the sprite
>     pop ix               ;(ix) has the graphics of the sprite
>     ex de,hl             ;\(de) has gfx of sprite
>                          ;/hl has addr. in video mem
>  PS_NewRow:
>     push bc
>     ld d,(ix)            ;d has graphics for one row of sprite
>     inc ix               ;point to next row of sprite
>     push af
>     push hl
>  PS_NewCol:
>     rl d
>     ld e,a
>     jr nc,PS_NoPixel
>     or (hl)
>  ;   ld (hl),a           ;Michael Optimization
>     jr PS_NextPixel
>  PS_NoPixel:
>     cpl                  ;complement of a, ~a
>     and (hl)             ;\ a = what's in video mem AND ~bit^2
>                          ; |only bit^2 is affected (erased)
>                          ;/ all others AND'ed w/1, which has no affect
>  ;   ld (hl),a           ;Michael Optimization
>  PS_NextPixel:
>     ld (hl),a            ;ld a back into video mem (where it should be)
>     ld a,e               ;restore bit^2 into a
>     rrca                 ;\circular rotation of a, so a affects next bit
>     jr nc,PS_SameByte    ;C flag set when the 1 in a is shifted out of a
>     inc hl               ;next byte in video memory
>  PS_SameByte:
>     djnz PS_NewCol       ;go to the next column if b not = 0
>     pop hl               ;restore the video mem address
>     pop af               ;restore the byte from FIND_PIXEL
>     ld de,16             ;\move down a row (which is 16 bytes)
>     add hl,de            ;/
>     pop bc               ;bc again contains the width and height
>     dec c                ;one less row to draw
>     jr nz,PS_NewRow      ;when c=0, don't draw anymore rows
>     pop hl               ;\
>     pop de               ; |pixel plotted so restore the registers
>     pop bc               ; |
>     pop ix               ;/
>  
>  ;***End Routine***
>  
>  
>  
>  
>  
>  
>  jr Wait    ;return to main program
>  
>  
>  ;End:
>  ;        ret
>  
>  Sprite:
>  
>  .db %00001000, %00001000

You should just do <.db 8,8>; makes the code easier to read.

>  
>  .db %00111100
>  .db %01100110
>  .db %11000011
>  .db %11000011
>  .db %11000011
>  .db %11000011
>  .db %01100110
>  .db %00111100
>  
>          .end
>  
>  Any help would be GREATLY appreciated.
>  
>  THanks
>  
>  Stu

Hope that fixes it.

JL
Macross Software