[stella] My very latest trick :-)

[Thomas Jentzsch <tjentzsch@xxxxxx>]

Hi,
for a long time, I have been thinking about a Boulderdash for 
the 2600. There are many problems (e.g. RAM) which are hard to 
solve. And then I had no idea how to display nice graphics.

Over the weekend I found some time, to make a quick hack of an 
idea, that was in my head for months now.

Like in my old RESPx example, I'm showing the PF and BK color 
and use black players to produce the graphics. But this time 
I'm displaying 2*6 (flickering) players that can have different 
shapes. Each player can use one of the two colors (plus black), 
but only with the lower PF resolution (4 pixel/color). 

The current demo is a only a very quick hack. Due to the very 
tight timing, the final code will require to run in RAM 
(selfmodifying code!) and I also haven't checked how much time 
it would cost to modify the code for a new line with different 
graphics. 

Tell me how it looks on a real TV please. Too much flicker? Is 
it worth investigating more time?

Here is some code snippet: 
(VDELPx = 1, COLUPx = 0, COLUPF = $20)
    ldx     #$24        ; 2
    ldy     #11         ; 2
.loopLeft2:
    lda     #0          ; 2
    sta     COLUBK      ; 3     @62 (@62..66)
    lda     PF1TblL,y   ; 5
    sta     PF1         ; 3     @70
    lda     Border ,y   ; 4
;-----------------------------------
    sta     GRP0        ; 3     @01
    lda     Sand,y      ; 4
    sta     GRP1        ; 3     @08
    lda     Diamond,y   ; 4
    sta     GRP0        ; 3     @15
    lda     PF2TblL,y   ; 4
    sta     PF2         ; 3     @22
    lda     Diamond,y   ; 4
    SLEEP   4           ; 4
    stx     COLUBK      ; 3     @33 (@32..33)
    sta     GRP1        ; 3     @36 (@36..40)
    lda     Wall,y      ; 4
    sta     GRP0        ; 3
    lda     Rock,y      ; 4
    sta     GRP1        ; 3
    sta     GRP0        ; 3
    dey                 ; 2
    bpl     .loopLeft2	; 2³

BTW: This would probaly become a Supercharger game. That's 
probably the only chance to find the necessary RAM.

Have fun!	
Thomas

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