Evaluate the current location of the vector beam?

[vectrexrc]

Hi

Is it possible to evaluate the current x,y location of the vector beam using code?

I have some code that is trying write a string of text out as a sequence of characters (vector object lists) with following call format:

JSR Reset0Ref        ; reset the beam
LDA #-60              ; y loc
LDB #$00              ; x loc
JSR Moveto_d        ; move beam to the draw position
LDU #string3         ; pointer to the string    
JSR drawtext         ; call my custom string drawing routine            

where

string1:

    DB "ABCDEFGHIJKLM",$80

eg. the beam is moved to the starting position outside the routine

This works fine when writing a text string of up to 6 characters - but after 6 the other characters become unstable. This must be because the total number of vectors being drawn are too large.

My idea to avoid this was to modify the routine to count how many characters have been written and then every 6,12 or 18 chars:

a) reset the beam using Reset0Ref 
b) calculate an appropriate offset to place the beam back at the end of the previous chars already drawn
c) move the beam using Moveto_d

then continue writing the remaining characters of the string again...

eg. split a large string into sets of 6 characters

I am wondering what is best to implement part b)


Question:

Is possible to evaluate the current location of the vector beam to help me achieve part b

Is there standard function to do that?

Or would I need to keep track myself in the code myself? maybe that would be more efficient?


In addition:

any ideas on how to do modular division of the char counter? eg in order to evaluate when to do something every 6 chars?

I guess every 4 or 8 would be easier?


Otherwise my routine is currently displaying text using the original Atari Tempest font successfully (it just does not like long strings).
As anticipated it was not visible in ParaJVE or ParaJVD but only when I tested on the the Vectrex using a VecMulti.

I would appreciate any advice. Thanks.

[christophertumber]

May 24, 2015 19:19:01 GMT -5 vectrexrc said:

Is possible to evaluate the current location of the vector beam

Not to the best of my knowledge.

Are these fixed width fonts?

If so, then you're kind of overthinking this.

Create a string printing routine (or break up your text if it's static) into X character chunks. I think I went with 6 characters but I don't remember off hand.

So if you are printing "ABCDEFGHIJKL" print it as "ABCDEF" and "GHIJKL". Since they're fixed width then given any specific scale (easier if you use very limited number of font sizes, ie; one) you know how much to offset the second string. Or any subsequent sub-strings. Depending how you set it up, you never really need to do any calculation or at most you need to do an addb.

If they're not fixed width, then you need a table with the width of each character. Every time you print a string, you'll need to reference this table for each character in that string to keep a running total of the offset needed for the next string chunk.