Drawing patterned lines

[vectrexrc]

Does anyone know how to draw a patterned line? eg. dotted or dashed etc


I think the standard bios line drawing routine is solid line only.



I think there is bios routine to draw a vector object with a pattern, but but how to just draw a single line that is patterned?



Is it possible?
 

Is it inefficient in terms of cycles to draw with patterned lines?



Any advice would be great.

[jfmateos]

I think you only have to store the patter in $C829 before calling Draw_Line_d

Drawing a patterned line is as efficient/fast as drawing a solid line... in fact, the solid lines are also patterned lines with pattern $FF

[binarystar]

Yeah as JFMateos says, change the pattern in $c829. $FF is default - a solid line. IIRC, each bit in the byte represents one line segment and one/(two?) of the bits determines whether the line has a dot at the beginning/end.

[cNp]

Good to know, thanks... been meaning to ask after this as I tried using different drawing routines (never really understanding the differences) to see any difference and found one that drew a dashed line on the emu... but it drew a solid line on real hardware so I just gave up on it.

Another thing I have to look at is pulling the draw bios routine I use out as an inline macro... when I looked before it didn't seem as simple as pulling other routines out...

cNp

[gauze]

anyone have any clue on what these expected "patterns" are? I messed around with a few things using Draw_VLp ($F410) but I haven't figured out what exactly happens except for values >=128 (high bit set on, continue processing data behind pointer in X-reg), even after reading the code (does some VIA register fiddling which controls D/A gun control type stuff?).
Note I have only checked in VIDE and ParaJVE not a real vectrex.

I did find this in BIOS but I couldn't reproduce any dashed/dotted lines in my emulator tests using Draw_VLp, just get either
a visible line or an invisible line, no dashing.

; Line patterns for boundary boxes

DF0FD: FCB %11100000
FCB %00111000
FCB %00001110
FCB %00000011

[Malban]

Hi,

doesn't suprise me - the BIOS Draw_VLp is buggy. It doesn't work as expected.
If you use Vide use a patterned line in vecci and build a runnable from it.

For the "export" I did an own Draw_VLp which works as expected.


In general a pattern is a "bit"-pattern, for each 1 a "dash" is drawn for each "0" a blank is drawn.
If you have eight dashs in a row that is a solid line - everythings else something in between.

Patterns must have the highest bit set, since 0 there is the "end" criterium for the list.

If you want to use BIOS routines, than use:
F434 Draw_Pat_VL_a ;
F437 Draw_Pat_VL ;
F439 Draw_Pat_VL_d

and set the pattern to $C823.

Also worth noting - the dashes get "longer" with vector strength, the "count" of dashes changes with scaling.

Regards
Malban

(The patterns in vecci are not drawn 100% correct! - That will not change :-))

[gauze]

Oct 18, 2016 14:11:45 GMT -5 Malban said:

Hi,

doesn't suprise me - the BIOS Draw_VLp is buggy. It doesn't work as expected.

blam

[limitzer0]

I just spent way too long messing with Draw_VLp… I wish I found this sooner.

[gtoal]

Oct 2, 2019 0:45:30 GMT -5 limitzer0 said:

I just spent way too long messing with Draw_VLp… I wish I found this sooner.

you might also look for drawSyncList - something I wish I'd found sooner.

G

[D-Type]

I just spent way too long messing with Draw_VLp… I wish I found this sooner.

Anyone have any simple code samples for patterned lines they can share with me on this, please?

I can't seem to get anything other than solid or blank lines.

UPDATE: OK, I literally got something working on my next compile. Would still like some samples though, please! :-)

Here's my code (in Forth):

here equ planeA
00 c,  6E c,   \ rel y, rel x
14 c, -1E c,
00 c, -32 c,
14 c, -1E c,
-28 c,  00 c,

: md_reset/move \ y -- ;
  _Reset0Ref 0 swap _Moveto_d
;

\ ;$FF ENABLES DOTTED LINE
\ ;$00 REQUESTS BLANK LINE
\ ;$02 IS SOLID LINE
\ ;$01 DELIMIT

: draw \ -- ; Draw tests.
  begin
     _Wait_Recal
     _Intensity_7F

      $3F VIA_t1_cnt_lo c! \ Set scaling factor
      $AA Vec_Pattern c!

     -$30 md_reset/move  4 Vec_Misc_Count c!  planeA _Draw_VL     \ Works OK
     -$50 md_reset/move  4 Vec_Misc_Count c!  planeA _Draw_Pat_VL \ Needs work...

     key?  \ press a key to end
  until
  key drop
;

[D-Type]

OK, I've sussed this - I guess I can do without code samples now!

First thing I did was comment out the code that sets a static pattern, from the compiled code i.e. 
\ $AA Vec_Pattern c! 

Then, from my Forth command prompt, if I set the pattern in $c829 and then run the Draw word (i.e. sub-routine) I get dashes. Setting to %10000000 gets me dots, then %1100... gets me short dashes, all the way to %11111110 to get very long dashes with a dot-sized gap. 

What is weird is that there is a constant number of dashes per vector, so on the display, from the PlaneA vector list I'm using, there is a vector that is about 3cm long and it has 4 dashes in it, the next vector is 1cm long and also has 4 (smaller) dashes in it. Same 4 vectors in all the others in the VL, regardless of their length.

So if you reset your Vectrex and look at the startup banner with two rectangles of moving clockwise/anti-clockwise dashes, these show the same thing i.e. same number of dashes for horizontal sides and vertical sides, regardless of length. Mind blown 

OK-0 %10000000 $c829 c! draw
OK-0 %11000000 $c829 c! draw
OK-0 %11100000 $c829 c! draw
OK-0 %11110000 $c829 c! draw
OK-0 %11111000 $c829 c! draw
OK-0 %11111100 $c829 c! draw
OK-0 %11111110 $c829 c! draw