What am I doing wrong??!?! BIOS routine Rot_VL_Mode

[gauze]

I was just messing around with some stuff and I cannot for the life of me get this routine to work.

the BIOS print out shows this for location and usage (edited for brevity):
; F61F Rot_VL_Mode ; ;
; ;
; The A register contains the rotation value, and the X contains a ;
; pointer to the vector list. The U register contains a pointer to a ;
; buffer into which the transformed points are to be saved. ;
; ;
; ENTRY DP = $C8 ;
; A-reg = rotation angle value (Rot_VL_Mode only) ;
; X-reg points to original vector list ;
; U-reg points to rotated vector list ;

I also checked against the bios print out from 1983 at this routine and the description of use is the same.

I verified that my original Mode list prints with Draw_VL_Mode (which I assume verifies it's valid), I am allocating RAM for the buffer where the list is supposed to be stored, I tried a variety of angle arguments and when I check the RAM in question in VIDE I get exactly 4 bytes back. The code is linked below.

https://gist.github.com/gauze/f97eed8dbcb086d0b26bd5dfdaa8ec84

does this Routine just not work or what am I doing wrong cause I do not see the error and I'm convinced it's me but I might be too trusting here .

[Malban]

The function should be called ROT_VL_Pattern.
The "2" in your vectorlist should have a negative value like "$ff" - than it works.

The "positive" mode is taken as "end of list" - value.

Malban

[gauze]

son of a bitch, yeah it does.

also it took me a while to figure out but I found where it's mentioned the angle argument is range $00-$3F (0-63) which isn't mentioned anywhere in the common disassembly and I could only find it in "Vectrex Programmers Manual vol II" with no explanations as to why, but there you go. I get that 360 can't be expressed in 8-bits but a little heads up in documentation would have been welcome haha.

[vectrexrc]

Dec 19, 2017 9:35:48 GMT -5 gauze said:

the angle argument is range $00-$3F (0-63)

so it is only possible to rotate object by 360/64 = 5.625 degrees?

is there way to rotate by a smaller degree? eg. smoother *

is 5 degrees considered smooth enough for vector game on vectrex?

(* other than using pre-calculated vector lists - which could potentially take up a lot of rom space)

[gauze]

it's possible if you write your own routines, using the built in BIOS routines, it's what we are stuck with.

[D-Type]

64 positions sounds like quite a lot to me! Pac-man only has 4 :-)

[gauze]

64 really isn't bad.