From 8303d83efab1ee1135cf2396a792479966ed2303 Mon Sep 17 00:00:00 2001
From: "B. Watson" <urchlay@slackware.uk>
Date: Tue, 8 Nov 2022 02:08:54 -0500
Subject: drunkwalk does spawning and plotting, too.

---
 dla.s       | 12 +-----------
 drunkwalk.s | 21 +++++++++++++++++----
 2 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/dla.s b/dla.s
index a18a23b..bae1b39 100644
--- a/dla.s
+++ b/dla.s
@@ -181,17 +181,7 @@ wl:
  jsr drawseed
 
 next_particle:
- ldy RANDOM ; spawn a new particle
- lda (spawn_x),y
- sta cursor_x
- lda (spawn_y),y
- sta cursor_y
- jsr drunkwalk     ; walk it around
- beq next_particle ; if it went out of bounds, try again
-
- ; particle stuck to an existing pixel, draw it
- jsr plot
-
+ jsr drunkwalk     ; spawn, walk around, plot (all in one)
  inc particles
  bne ph_ok
  inc particles+1
diff --git a/drunkwalk.s b/drunkwalk.s
index ca017c0..02ab67d 100644
--- a/drunkwalk.s
+++ b/drunkwalk.s
@@ -6,12 +6,16 @@
 ;;; possible.
 ; Y and X are backwards: Y holds the X coordinate, and X holds the Y coordinate.
 ; Has to be, because there's no (zpind),x addressing mode.
-oob:
- rts
 
 drunkwalk:
- ldy cursor_x           ; 3
- ldx cursor_y           ; 3
+oob:
+ ldy RANDOM ; spawn a new particle
+ lda (spawn_x),y
+ sta cursor_x
+ lda (spawn_y),y
+ sta cursor_y
+ tax
+ ldy cursor_x
 
  lda lineaddrs_l,x    ; 5
  sta pixptr           ; 3
@@ -132,4 +136,13 @@ check_lrd:
  jmp move_pixel
 
 stick:
+ ; pixel stuck next to an existing pixel, draw it and return.
+ ldx cursor_y
+ lda lineaddrs_l,x
+ sta pixptr
+ lda lineaddrs_h,x
+ sta pixptr+1
+ ldy cursor_x
+ lda #1
+ sta (pixptr),y
  rts
-- 
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