Snakes are drawn in reverse, so it looks like they are crawling over each other rather than under. It is the little things in life that matter.
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[Upon opening the Well of the Souls and peering down]
Sallah: Indy, why does the floor move?
Indiana: Give me your torch.
[Indy takes the torch and drops it in]
Indiana: Snakes. Why'd it have to be snakes?
Sallah: Asps... very dangerous. You go first.
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REM Snake Walk 2
REM T Street
REM 2014-11-12
REM slightly improved snake program, now
REM with more snakes!
MODE 10 : OFF
SCREEN_WIDTH% = 1440
SCREEN_HEIGHT% = 1152
REM snake parameters
SNAKE_RADIUS% = 16 : REM size of the segments
SEGMENTS% = 26 : REM don't change to larger than this
REM create each snake
DIM snake1{ x%(SEGMENTS%-1), y%(SEGMENTS%-1), head%, tail%, dir%, red%, green% }
DIM snake2{} = snake1{}
DIM snake3{} = snake1{}
DIM snake4{} = snake1{}
DIM snake5{} = snake1{}
DIM snake6{} = snake1{}
DIM snake7{} = snake1{}
DIM snake8{} = snake1{}
REM setup the initial conditions for the snake
PROC_initialSnake( snake1{} )
PROC_initialSnake( snake2{} )
PROC_initialSnake( snake3{} )
PROC_initialSnake( snake4{} )
PROC_initialSnake( snake5{} )
PROC_initialSnake( snake6{} )
PROC_initialSnake( snake7{} )
PROC_initialSnake( snake8{} )
REM main loop
REPEAT
*refresh off
PROC_drawSnake( snake1{} )
PROC_drawSnake( snake2{})
PROC_drawSnake( snake3{})
PROC_drawSnake( snake4{})
PROC_drawSnake( snake5{})
PROC_drawSnake( snake6{})
PROC_drawSnake( snake7{})
PROC_drawSnake( snake8{})
*refresh on
PROC_moveSnake( snake1{} )
PROC_moveSnake( snake2{} )
PROC_moveSnake( snake3{} )
PROC_moveSnake( snake4{} )
PROC_moveSnake( snake5{} )
PROC_moveSnake( snake6{} )
PROC_moveSnake( snake7{} )
PROC_moveSnake( snake8{} )
WAIT 5 : REM wait a 'mo
CLS
UNTIL FALSE
DEFPROC_initialSnake( this{} )
LOCAL i%
REM intial position of snake
FOR i% = 0 TO SEGMENTS%-1
this.x%(i%) = i% + 8
this.y%(i%) = 12
NEXT
this.head% = SEGMENTS%-1
this.tail% = 0
this.dir% = RND(4) : REM initial direction
this.red% = RND(255-SEGMENTS%*6) : REM colour of snake
this.green% = RND(255-SEGMENTS%*6) : REM colour of snake
ENDPROC
DEFPROC_drawSnake( this{} )
REM plots one snake on the screen
LOCAL colCycle%
LOCAL i%
LOCAL ok%
i% = this.tail%
WHILE NOTok%
COLOUR 2, this.red%+colCycle%*6, this.green%+colCycle%*6, 0
GCOL 0,2
colCycle% +=1
PROC_circle( this.x%(i%), this.y%(i%) )
i% += 1
IF i% >= SEGMENTS% THEN i% = 0
IF i% = this.head% THEN
ok% = TRUE
PROC_circle( this.x%(i%), this.y%(i%) )
ENDIF
ENDWHILE
ENDPROC
DEFPROC_moveSnake( this{} )
LOCAL dir%, ok%
LOCAL newHead%, newTail%
LOCAL checkx%, checky%
newHead% = this.head% + 1
IF newHead%=SEGMENTS% THEN
newHead% = 0
ENDIF
newTail% = this.tail% + 1
IF newTail% =SEGMENTS% THEN
newTail% = 0
ENDIF
REPEAT
ok% = TRUE
REM check snake is not going back on itself
REPEAT
dir% = RND(4)
UNTIL FN_dirOk(dir%, this.dir% )
REM check that snake will not move off the screen
CASE dir% OF
WHEN 1
checkx% = this.x%(this.head%) +1
WHEN 2
checkx% = this.x%(this.head%) -1
WHEN 3
checky% = this.y%(this.head%) + 1
WHEN 4
checky% = this.y%(this.head%) -1
ENDCASE
IF dir% = 1 THEN
IF checkx%*SNAKE_RADIUS%*2 > SCREEN_WIDTH% THEN
ok% = FALSE
ENDIF
ENDIF
IF dir% = 2 THEN
IF checkx%*SNAKE_RADIUS%*2 <= SNAKE_RADIUS%*2 THEN
ok% = FALSE
ENDIF
ENDIF
IF dir% = 3 THEN
IF checky%*SNAKE_RADIUS%*2 > SCREEN_HEIGHT% THEN
ok% = FALSE
ENDIF
ENDIF
IF dir% = 4 THEN
IF checky%*SNAKE_RADIUS%*2 <= SNAKE_RADIUS%*2 THEN
ok% = FALSE
ENDIF
ENDIF
UNTIL ok%
REM snake has made a valid random move
CASE dir% OF
WHEN 1
this.x%(newHead%) = this.x%(this.head%) +1
this.y%(newHead%) = this.y%(this.head%)
WHEN 2
this.x%(newHead%) = this.x%(this.head%) -1
this.y%(newHead%) = this.y%(this.head%)
WHEN 3
this.y%(newHead%) = this.y%(this.head%) +1
this.x%(newHead%) = this.x%(this.head%)
WHEN 4
this.y%(newHead%) = this.y%(this.head%) -1
this.x%(newHead%) = this.x%(this.head%)
ENDCASE
this.head% = newHead%
this.tail% = newTail%
this.dir% = dir%
ENDPROC
DEFFN_dirOk( direction%, current% )
REM check snake not moving back on itself
IF ABS(direction%-current%) = 1 AND direction%+current% <> 5 THEN
= FALSE
ELSE
= TRUE
ENDIF
DEFPROC_circle( x%, y% )
CIRCLE FILL x%*SNAKE_RADIUS%*2, y%*SNAKE_RADIUS%*2, SNAKE_RADIUS%
ENDPROC