Code:
'prueba de cola de serpiente
' Marcus: You can remove this, just checking some things.
#dbg
'variables-----------------------
' Marcus: I think list_body should belong to player ================================================
'visible player,list_body
visible player
' ==================================================================================================
set window "serpiente",640,480,false
set redraw off
'player-----------------------------
function Player()
obj = []
obj.radius = 14
obj.x = 320 - obj.radius/2
obj.y = 240 - obj.radius/2
obj.speedX = 0
obj.speedY = 0
obj.Active = true
' Marcus: Putting body list here and a list of recorded head positions =========================
obj.bodyList = []
obj.positions = []
' ==============================================================================================
' Marcus: Add one body part to player ==========================================================
obj.AddBody = function()
body = Body(0, 0)
this.bodyList[sizeof(this.bodyList)] = body
' Not sure when AddBody might be called, so calling UpdateBody here too.
this.UpdateBody()
endfunc
' ==============================================================================================
obj.update = function()
if this.Active = true
this.move()
' Marcus: Reposition body parts ========================================================
this.UpdateBody()
' ======================================================================================
this.Draw()
endif
endfunc
' Marcus: Set body parts' positions ============================================================
obj.UpdateBody = function()
if sizeof(this.bodyList)
' We position the body parts one after one, starting with the one closest to the head.
' dist is the calculated travel distance between the head and the current body part.
' Initiate it to the radius of the head.
dist = this.radius
for i = 0 to sizeof(this.bodyList) - 1
b = this.bodyList[i]
' Add radius of body part to dist.
dist = dist + b.radius
' Divide dist by the speed of the snake to convert the traveled distance to an
' index in the position list. Use 'min' to make sure it's not outside the list.
index = min(int(dist/2), sizeof(this.positions) - 1)
if index >= 0
' Convert single number coordinates to x and y.
'b.y = int(this.positions[index]/width(primary))
'b.x = int(this.positions[index]%width(primary))
b.x = this.positions[index][0]
b.y = this.positions[index][1]
else
' No recorded positions, put at head position.
b.x = this.x
b.y = this.y
endif
' Add radius of body part to dist.
dist = dist + b.radius
next
endif
endfunc
' ==============================================================================================
obj.Draw = function()
' Marcus: Draw body parts ==================================================================
if sizeof(this.bodyList)
for i = 0 to sizeof(this.bodyList) - 1 this.bodyList[i].Draw()
endif
' ==========================================================================================
set color 255,204,0
draw ellipse this.x,this.y,this.radius,this.radius,true
endfunc
obj.move = function()
if keydown(KEY_RIGHT,false)
this.speedX = 2
this.speedY = 0
endif
if keydown(KEY_LEFT,false)
this.speedX = -2
this.speedY = 0
endif
if keydown(KEY_UP,false)
this.speedX = 0
this.speedY = -2
endif
if keydown(KEY_DOWN,false)
this.speedX = 0
this.speedY = 2
endif
' Marcus: Save previous position ===========================================================
if this.speedX or this.speedY
' I store the position, x and y, as a single number.
'insert this.positions, 0, this.y*width(primary) + this.x
insert this.positions, 0, [this.x, this.y]
' Store only 5000 positions for now, might have to increase it depending on how long
' the snake can become.
if sizeof(this.positions) > 5000 free key this.positions, 5000
endif
' ==========================================================================================
this.x = this.x + this.speedX
this.y = this.y + this.speedY
endfunc
return obj
endfunc
'end player--------------------------
'body--------------------------------
function Body(x,y)
obj = []
obj.radius = 10
obj.x = x - obj.radius/2
obj.y = y - obj.radius/2
obj.update = function()
this.Draw()
endfunc
obj.Draw = function()
set color 255,0,204
draw ellipse this.x,this.y,this.radius,this.radius,true
endfunc
return obj
endfunc
'end body----------------------------
'iniciar variables-------------------
player = Player()
list_body = []
list_body[sizeof(list_body)] = Body(320,64)
list_body[sizeof(list_body)] = Body(320-32,64)
list_body[sizeof(list_body)] = Body(320-64,64)
while not keydown(KEY_ESCAPE,true)
set color 0,0,0
cls
if keydown(KEY_SPACE, true) player.AddBody()
'actualizar objetos del juego-----------
player.update()
if sizeof(list_body)
for i = 0 to sizeof(list_body)-1
list_body[i].update()
next
endif
'---------------------------------------
' Marcus: Some debug output ====================================================================
set color 255, 255, 255
set caret 0, 0
wln "PRESS SPACE BAR TO ADD BODY PARTS"
wln
wln "bodyparts: " + sizeof(player.bodyList)
wln "recorded positions: " + sizeof(player.positions)
' ==============================================================================================
fwait 60
redraw
wendI've marked my changes with "Marcus"
This solution is probably not very good. The head's position is always recorded into a list, player.positions. Currently I store a maximum of 5000 positions, which covers a snake length of 10,000 pixels (because the speed of the snake is 2). Then I "simply" position the body parts, using the list of recorded positions, in player.UpdateBody.
Press space bar to add body parts.
Edit But as with the other snake code I posted, this is NOT a very smart solution. It should be enough to store the positions where the player turns, and then use the distance between the head and these points to calculate the positions of the body parts.