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Moving sprites in a circle

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_player1537:
Axe doesn't have a built in sin routine yet.  I'll have to try what you were saying.
*looks for Will_W's math.inc file*

Will_W:
calc84 made some wicked optimizations to it, maybe he'll post them here if we're lucky.

--- Code: ---Sin_A:
;input a in pi/256 radians from [0,pi)
;output l is a binary value in the range [0,1)
;destroys h,de
;a is unmodified
;Will West
ld h,a
ld e,h
call HtimesE;hl=x^2
ex de,hl;x^2

ld l,a
ld h,0
or a;reset carry
sbc hl,de
        add hl,hl
        add hl,hl
ret

HtimesE:
 ld l,0
 ld d,0
 
 sla h       ; optimised 1st iteration
 jr  nc,$+3
 ld  l,e

 add hl,hl       ;1
 jr  nc,$+3      ;
 add hl,de       ;
 
 add hl,hl       ;2
 jr  nc,$+3      ;
 add hl,de       ;

 add hl,hl       ;3
 jr  nc,$+3      ;
 add hl,de       ;
 
 add hl,hl       ;4
 jr  nc,$+3      ;
 add hl,de       ;
 
 add hl,hl       ;5
 jr  nc,$+3      ;
 add hl,de       ;
 
 add hl,hl       ;6
 jr  nc,$+3      ;
 add hl,de       ;
 
 add hl,hl       ;7
 jr  nc,$+3      ;
 add hl,de       ;
 
 ret

 
;;=================================================================================
;;does sin(a) where a is between (-pi,pi) and is in units of
;;128/pi radians
;;inputs a
;;outputs a
;;destroys bc,de,hl
;;=================================================================================
Sin_A_Signed:
 bit 7,a
 jr z,Sin_A_Signed2
 neg
 sla a
 call Sin_A
 ld a,l
 neg
 ret
Sin_A_Signed2:
 sla a
 call Sin_A
 ld a,l
 ret
--- End code ---

DJ Omnimaga:

--- Quote from: SirCmpwn on April 06, 2010, 06:20:31 pm ---That looks almost right.
The Pt-On line should look like this:
         Look here↓
Pt-On(X*cos(Z)+Y*sin(Z),X*sin(Z)-Y*cos(Z
And, it can be optimized to this as well:
Pt-On(Xcos(Z)+Ysin(Z),Xsin(Z)-Ycos(Z   // Removed "*" tokens
Keep in mind that it rotates around the origin, or the 0, 0 point.  Also, you can keep adding 1 to Z, and it will still work.  Z does not have to be between 0 and 360, 361 will rotate it 1 degree.

--- End quote ---
woops lol why did I forgot about those *? :D, I guess when I am used more to Axe, if I decide to go back to BASIC afterward, I'll have to be careful ^^

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