[A83] Re: Mario Side-Scroller

To: assembly-83@lists.ticalc.org
Subject: [A83] Re: Mario Side-Scroller
From: "Dan Weiss" <dwedit@hotmail.com>
Date: Sun, 27 May 2001 13:12:14 -0500
Reply-To: assembly-83@lists.ticalc.org

Here's some code that checks what tile is at X,Y  (you need to check 4 
points to see if you can move an 8x8 sprite, 6 points for an 8x16 sprite)

GetXY:
  ;NOTE: This assumes you stored the map data vertically!
  ;Input e=y,hl=x
  ;Output a= tile at (x,y)
  ld a,l
  and %11111000
  ld l,a
  ;add hl,hl    ;only do this if your map is 16 high instead of 8
  ld 0,d
  add hl,de
  ld de,map         ;or whatever you named the map memory
  add hl,de
  ld a,(hl)
  ret

When you're moving an 8x8 sprite, you need to check if an unwalkable terrain 
is in that direction.

RIGHT:

####' <- check this (X+8,Y)
####
####
####. <- And this   (X+8,Y+7)

LEFT:
Check this (x-1,y) -> '####
_                      ####
_                      ####
And this (x-1,y+7) -> .####

UP:
Check This:   (x,y-1) -> .  . <- And this (x+7,y-1)
_                        ####
_                        ####
_                        ####
_                        ####

DOWN:
_                        ####
_                        ####
_                        ####
_                        ####
Check This:   (x,y+8) -> '  ' <- And this (x+7,y+8)


Those little diagrams tell you to check a couple points to determine if you 
can go in that direction.  If any of those points is a wall, then you can't 
go in that direction.  (to check which brick mario hit with his head, the 
brick is at (x+4,y-1))


And now these same crappy diagrams for 8x16 sprites:

RIGHT:

####' <- check this (X+8,Y)
####
####
####
####' <- And this   (X+8,Y+8)
####
####
####. <- And this   (X+8,Y+15)

LEFT:
Check this (x-1,y) -> '####
_                      ####
_                      ####
_                      ####
And this (x-1,y+8) -> '####
_                      ####
_                      ####
And this (x-1,y+15)-> .####

UP:
Check This:   (x,y-1) -> .  . <- And this (x+7,y-1)
_                        ####
_                        ####
_                        ####
_                        ####
_                        ####
_                        ####
_                        ####
_                        ####

DOWN:
_                        ####
_                        ####
_                        ####
_                        ####
_                        ####
_                        ####
_                        ####
_                        ####
Check This:  (x,y+16) -> '  ' <- And this (x+7,y+16)


Hope this stuff helped.




>From: Sk8a4good@aol.com
>Reply-To: assembly-83@lists.ticalc.org
>To: assembly-83@lists.ticalc.org
>Subject: [A83] Re: Mario Side-Scroller
>Date: Sun, 27 May 2001 10:47:21 EDT
>
>
>OK, i used crashman's sprite routine and got that to work just fine.  How 
>do
>I check which tile the sprite is on if its coordinates are in ypos and 
>xpos?
>
>

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