Meteors added :)

Atari/gr_basics.asm

@@ -161,6 +161,36 @@ ClearPlot
     rts
 .endp
 
+; -----------------------------------------
+.proc ExPlot  ;ExPlot (EplotX, EplotY)
+; EOR plot:
+; Inverts color of a pixel
+; Note: No coordinate control!!!
+;       With off-screen coordinates, it can damage main program.
+; -----------------------------------------
+    ; let's calculate coordinates from xdraw and ydraw
+    ;xbyte = xbyte/8
+    lda EplotX+1
+    lsr
+    lda EplotX
+    ror ;just one bit over 256. Max screenwidth = 512!!!
+    lsr
+    lsr
+    sta EplotByte
+    ;---
+    ldx EplotY
+    ldy linetableL,x
+    lda linetableH,x
+    sta EplotByte+1
+
+    ldx EplotX   ; optimization (256 bytes long bittable)
+
+    lda (EplotByte),y
+    eor bittable1_long,x
+    sta (EplotByte),y
+    rts
+.endp
+
 ; -----------------------------------------
 .proc point_plot
 ; -----------------------------------------

Atari/interrupts.asm

@@ -142,6 +142,54 @@ lab2
     jsr RASTERMUSICTRACKER+3    ;1 play
     ; ------- RMT -------
 SkipRMTVBL
+    ; ------ meteors ------ start
+    bit Mcounter
+    bpl MeteorOnSky
+    bit MeteorsFlag
+    bmi SkipMeteors
+    ; randomize meteor
+    lda random
+    and #%11111111
+    bne SkipMeteors
+    lda random
+    sta Mpoint1X
+    sta Mpoint2X
+    lda #0
+    sta Mpoint1X+1
+    sta Mpoint2X+1
+    lda random
+    and #$1f
+    sta Mpoint1Y
+    sta Mpoint2Y
+    mva #10 Mcounter
+MeteorOnSky
+    lda Mpoint1Y
+    cmp #64
+    beq NoFirstPlot
+    sta EplotY
+    inc Mpoint1Y
+    mwa Mpoint1X EplotX
+    inw Mpoint1X
+    jsr Explot
+NoFirstPlot
+    lda Mcounter
+    beq @+
+    dec Mcounter
+    bpl SkipSecondPlot
+@   lda Mpoint2Y
+    cmp #64
+    bne GoSecondPlot
+    mva #$ff Mcounter
+    bmi SkipMeteors
+GoSecondPlot
+    sta EplotY
+    inc Mpoint2Y
+    mwa Mpoint2X EplotX
+    inw Mpoint2X
+    jsr Explot
+SkipSecondPlot
+SkipMeteors
+    ; ------ meteors ------ end
     bit ScrollFlag
     bpl EndOfCreditsVBI
 CreditsVBI