Useful Routines
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Useful Routines
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Jim e


Advanced Member


Joined: 05 Sep 2005
Posts: 360
Posted: 27 Mar 2006 04:22:02 pm    Post subject:
Yeah all that setting and restting accmoplishes nothing, add a,b \ rra is all you need. Though I don't know if that can be considered a routine.
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kermmartian
Site Admin Kemetech


Calc Guru


Joined: 20 Mar 2004
Posts: 1220
Posted: 27 Mar 2006 09:08:46 pm    Post subject:
Better Hotspot

Code:
;----------Hot spot detection-----------
;inputs: b,c (first x and y cor)
;        d,e (last x and y cor)
;        h,l (current x,y)
;output: "z" flag [either true (set) or false (reset)]

hdetect:
  ld a,h
  cp b
  jr c,hno_detect
  cp d
  jr nc,hno_detect
  ld a,l
  cp c
  jr c,hno_detect
  cp e
  jr nc,hno_detect
hyes_detect:
  xor a
  or a
  ret
hno_detect:
  xor a
  cp 1
  ret
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DarkerLine
ceci n'est pas une |


Super Elite (Last Title)


Joined: 04 Nov 2003
Posts: 8328
Posted: 28 Mar 2006 12:35:09 pm    Post subject:
What's a hot spot?

It would be more efficient if you used the 'c' flag:

Code:
;----------Hot spot detection-----------
;inputs: b,c (first x and y cor)
;        d,e (last x and y cor)
;        h,l (current x,y)
;output: "c" flag [either true (set) or false (reset)]

hdetect:
  ld a,h
  cp b
  ccf
  ret nc
  cp d
  ret nc
  ld a,l
  cp c
  ccf
  ret nc
  cp e
  ret


Last edited by Guest on 28 Mar 2006 03:13:25 pm; edited 1 time in total
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kermmartian
Site Admin Kemetech


Calc Guru


Joined: 20 Mar 2004
Posts: 1220
Posted: 28 Mar 2006 02:11:02 pm    Post subject:
Thought of that after I posted it. :)

Hotspot: basically it checks if h>b, l>c, h<d, and l<e.

Last edited by Guest on 28 Mar 2006 02:11:55 pm; edited 1 time in total
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Liazon
title goes here


Bandwidth Hog


Joined: 01 Nov 2005
Posts: 2007
Posted: 28 Mar 2006 05:08:40 pm    Post subject:
does somebody have a routine that sees if two sprites collide by XORing the contents to see if they overlap?
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Rezek
Better Than You


Calc Guru


Joined: 24 Apr 2005
Posts: 1229
Posted: 28 Mar 2006 06:15:42 pm    Post subject:
XOR them both to the screen using ionsprite, then use bounding box detection.

Last edited by Guest on 28 Mar 2006 06:16:01 pm; edited 1 time in total
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CoBB


Active Member


Joined: 30 Jun 2003
Posts: 720
Posted: 29 Mar 2006 02:47:50 am    Post subject:
What would be the point of that?

The solution isn't too complicated. First do a bounding box check to see if collision is possible at all. If those overlap, determine which bytes they share. For the rest, you need a sprite-sized buffer. LD the conflicting bytes of the first sprite to the buffer (after shifting, of course), and start ANDing the second (again, only AND the bytes that are shared with the other sprite and ignore the rest). If the result of an AND is nonzero, you have a pixel-level collision. If every conflicting byte gives zero after the ANDing, there is no collision.
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D-Tal


Newbie


Joined: 23 Mar 2006
Posts: 7
Posted: 29 Mar 2006 10:22:35 am    Post subject:
CoBB wrote:
[quote name='D-Tal' date='Mar 27 2006, 04:21 PM']add a,b
res 0, a
jr nc, label ; corrected syntax...
set 0, a
label:
rrca

Why not just add a,b \ rra?
[post="73161"]<{POST_SNAPBACK}>[/post]
[/quote]

HehHeh...
And what happens if you try to average 250 and 252 then, mmm? Neutral
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CoBB


Active Member


Joined: 30 Jun 2003
Posts: 720
Posted: 29 Mar 2006 11:02:15 am    Post subject:
You get 251.

1. You should read up on rotate and shift instructions.
2. You should actually run the code before questioning its correctness. Very Happy
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DarkerLine
ceci n'est pas une |


Super Elite (Last Title)


Joined: 04 Nov 2003
Posts: 8328
Posted: 29 Mar 2006 11:49:21 am    Post subject:
It's that "carry bit gets rotated back in" thing.
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D-Tal


Newbie


Joined: 23 Mar 2006
Posts: 7
Posted: 29 Mar 2006 03:20:20 pm    Post subject:
ouch

oops Confused -----> :confused: -----> Neutral -----> :blush:


Still, thanks for the tip. I would have gone off and used my old code, wasting untold bytes!
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Rezek
Better Than You


Calc Guru


Joined: 24 Apr 2005
Posts: 1229
Posted: 29 Mar 2006 04:58:31 pm    Post subject:
Quote:
What would be the point of that?


Maybe I misunderstood what he meant, I thought he wanted something that would write two sprites to gbuf, and then check if they had collided or not. Guess not though!
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Liazon
title goes here


Bandwidth Hog


Joined: 01 Nov 2005
Posts: 2007
Posted: 29 Mar 2006 08:46:43 pm    Post subject:
CoBB wrote:
What would be the point of that?

The solution isn't too complicated. First do a bounding box check to see if collision is possible at all. If those overlap, determine which bytes they share. For the rest, you need a sprite-sized buffer. LD the conflicting bytes of the first sprite to the buffer (after shifting, of course), and start ANDing the second (again, only AND the bytes that are shared with the other sprite and ignore the rest). If the result of an AND is nonzero, you have a pixel-level collision. If every conflicting byte gives zero after the ANDing, there is no collision.
[post="73309"]<{POST_SNAPBACK}>[/post]


thanks! i ask only because somebody wrote a 68k version that does that.
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Adm.Wiggin
aka Tianon


Know-It-All


Joined: 02 Jun 2003
Posts: 1874
Posted: 20 Apr 2006 04:52:19 pm    Post subject:
Wow. I turn my back for a few months, and you guys have a total disregard for the rules. Disgraceful. I guess we can now nullify the discussion rule, seeing as how nobody really followed it. Oh well, it seems like you had some good discussion. Keep bringing in the cool routines and stuff!
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WikiGuru
ADOS (Attention deficit... Oh! Shiny!)


Elite


Joined: 15 Sep 2005
Posts: 923
Posted: 17 May 2006 06:26:57 pm    Post subject:
time to revive the topic...

Center Text

Code:
;input:hl points to string
;output: string displayed centered on screen
;destroyed: all registers
;other remarks: (penrow) must be set before calling this sub-routine
;               first byte of string must be the length of the string

centertxt:
 bcall(_SStringLength)
 ld a,96        ;width of screen
 sub b          ;subtract width of string
 rra             ;divide by 2 to be centered
 ld (pencol),a
 ld b,(hl)
 inc hl
 bcall(_VPutSN)
 ret

;to call:

...
ld hl,0
ld (penrow),hl
ld hl,txtTest
call centertxt
...

txtTest:
 .db 11,"Sample Text"
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Liazon
title goes here


Bandwidth Hog


Joined: 01 Nov 2005
Posts: 2007
Posted: 17 May 2006 09:42:08 pm    Post subject:
that is kinda cool to have.
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WikiGuru
ADOS (Attention deficit... Oh! Shiny!)


Elite


Joined: 15 Sep 2005
Posts: 923
Posted: 18 May 2006 04:37:39 pm    Post subject:
Small useful piece of code (Might not be so useful for intermediate-advance programmers).

Type Write

Code:
;input: hl points to string (optional argument: b to set type speed)
;output: string displayed at set location (must set penrow and pencol before calling)
;destroyed: all but c

type:
 ld a,(hl)
 or a
 ret z
 inc hl
; cp b                  ;optional line
;call nz,pause      ;  -or- (next 2 lines)
 ld b,30
 call pause
 bcall(_VPutMap)
 jr type

pause:
 ei
 halt
 djnz pause
 di
 ret

;To call:

 ...
 ld hl,0
 ld (penrow),hl
 ld b,
 ld hl,txtTest
 call type
 ...

txtTest:
 .db "Sample Text",0
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alexrudd
pm me if you read this


Bandwidth Hog


Joined: 06 Oct 2004
Posts: 2335
Posted: 18 May 2006 06:04:20 pm    Post subject:
What's the point of calling pause instead of just copying the code where you need it?
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WikiGuru
ADOS (Attention deficit... Oh! Shiny!)


Elite


Joined: 15 Sep 2005
Posts: 923
Posted: 19 May 2006 05:28:27 pm    Post subject:
Sorry, I wasn't specific enough. It's a type-writer effect.
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DarkerLine
ceci n'est pas une |


Super Elite (Last Title)


Joined: 04 Nov 2003
Posts: 8328
Posted: 19 May 2006 05:51:35 pm    Post subject:
What he means is, instead of doing
Code:
type:
  ld a,(hl)
  or a
  ret z
  inc hl
  ld b,30
  call pause
  bcall(_VPutMap)
  jr type

pause:
  ei
  halt
  djnz pause
  di
  ret
you could do
Code:
type:
  ld a,(hl)
  or a
  ret z
  inc hl
  ld b,30
  ei
pause:
  halt
  djnz pause
  di
  bcall(_VPutMap)
  jr type
  ret


Last edited by Guest on 19 May 2006 05:51:58 pm; edited 1 time in total
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Useful Routines
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