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daveculp
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Joined: 02/07/2020
Location: United States
Posts: 22

Posted: 09:46pm 08 Jul 2020

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Im trying to draw a simple fractal tree which draws a horizontal line then recursively draws two lines from the end point of that line by rotating -25 and + 25 degrees then keeps going fro a set number of iterations.

Here is the code, a bit messy as I've been fiddling around with it.:

The print statements are simply debug statements to let me see some values and can be REM'd out.

drawTreeLeft(MM.HRES/2, MM.VRES,-90,10)
drawTreeRight(MM.HRES/2, MM.VRES,-90,10)

SUB drawTreeLeft (x1,y1, angle, iter)
� if iter >0 then

� �x2 = x1 + int(cos( RAD(angle) ) * iter * 10.0)
� �y2 = y1 + int(sin( RAD (angle) ) * iter * 10.0)

� �print angle,":";x1,y1,":",x2,y2
� �
� �line x1,y1,x2,y2,1,RGB(brown)
� �
� �drawTreeLeft(x2,y2, angle -25, iter - 1)
� �REM drawTree(x2,y2, angle +25, iter - 1)
�else
� �circle x1,y1,3,1,1,RGB(GREEN), RGB(GREEN)
�end if
END SUB

SUB drawTreeRight (x1,y1, angle, iter)
�if iter >0 then

� �x2 = x1 +int(( cos( RAD(angle) )) * iter * 10.0)
� �y2 = y1 +int(( sin( RAD (angle) )) * iter * 10.0)

� �print angle,":";x1,y1,":",x2,y2
� �line x1,y1,x2,y2,1,RGB(brown)
� �
� �REM drawTree(x2,y2, angle -25, iter - 1)
� �drawTreeRight(x2,y2, angle +25, iter - 1)
�else
� �circle x1,y1,3,1,1,RGB(GREEN), RGB(GREEN)
�end if
END SUB

The odd behavior is the following two things:

1. �x1 and x2 and y1 and y2 turn out to be the same and they shouldnt. �I NEVER change the value of x1 and y1. �Why is this?

2. �Problem #1 is solved if I do something like the following in the function:

drawTreeLeft(MM.HRES/2, MM.VRES,-90,10)
drawTreeRight(MM.HRES/2, MM.VRES,-90,10)

SUB drawTreeLeft (x1,y1, angle, iter)
� start_x = x1
� start_y = y1
� if iter >0 then

� �x2 = x1 + int(cos( RAD(angle) ) * iter * 10.0)
� �y2 = y1 + int(sin( RAD (angle) ) * iter * 10.0)

� �print angle,":";x1,y1,":",x2,y2
� �
� �line start_x,start_y,x2,y2,1,RGB(brown)
� �
� �drawTreeLeft(x2,y2, angle -25, iter - 1)
� �REM drawTree(x2,y2, angle +25, iter - 1)
�else
� �circle x1,y1,3,1,1,RGB(GREEN), RGB(GREEN)
�end if
END SUB

3. �I originally had it as one function which would call the drawTree sub twice (see the REM), one for drawing the left branch and one for the right. �However, it only ever drew the left branch.

4. �It should be recursively calling the drawTree function for EVERY LINE, but it doesn't.

I figure #3 and #4 are probably due to the way MMBASIC handles recursion and I know there is a limit of 50 recursive calls. �I will probably need to figure out another way to do this.

I cant figure out #1 though. �Why are x1 and y2 being set to x2 and y2?
Edited 2020-07-09 07:50 by daveculp

vegipete

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Joined: 29/01/2013
Location: Canada
Posts: 1132

Posted: 10:45pm 08 Jul 2020

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Does it improve if you use local variables in the subroutines?

Visit Vegipete's *Mite Library for cool programs.

TassyJim

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Joined: 07/08/2011
Location: Australia
Posts: 6283

Posted: 12:14am 09 Jul 2020

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How about "Christmas in July"

' seasons greetings

option explicit
option default float
mode 1
dim stX=mm.hres/2 'Tree starting point
dim stY=mm.vres*0.9
dim newX, newY, leng
dim angle = 30 '-30
dim stL = mm.vres/5
dim delta = stL/7
dim dr = 270
dim TurtleSpeed = 15 'speed options
DIM as float stack(100) 'FILO stack
DIM AS INTEGER cols(6)
cols(0)= RGB(RED)
cols(1)= RGB(WHITE)
cols(2)= RGB(yellow)
cols(3)= RGB(green)
cols(4)= RGB(blue)
cols(5)= RGB(magenta)

dim stackpos=1
dim c=0

' melody globals
DIM AS FLOAT melody(160,2)
DIM AS INTEGER tonePos, endTone, endMelody, t
endMelody = 1 ' needs to be set so that the first melody will start playing

CLS

do
IF endMelody = 1 THEN
if tempr(42) <> 1000 then ' only print temperature if available
text stX, stY+30, " "+str$(tempr(42),2,2)+" C ", cm
endif
t = (t+1) mod 2
select case t ' rotate melodies
case 0
RESTORE jingleBells
case 1
restore jinglebells2
end select
playMelody
ENDIF
newX=stX
newY=stY
leng = stL
angle = 0 - angle ' flip this each cycle to give windscreen washer action
dr = 270
c=(c+1) mod 6
LINE newX, newY-1, newX, newY ,1,cols(c)
drawtree
loop
END

SUB drawtree
local oldx, oldy, c, n
IF endTone = 1 THEN playNextTone
IF (leng > 0) THEN
c = int(rnd()*6)
oldX=newX
oldY=newY
newX=oldX - COS(RAD(dr))*leng
newY=oldY + SIN(RAD(dr))*leng
LINE oldX, oldY, newX, newY,1,cols(c)
for n = 1 to TurtleSpeed ' break up the pause to allow for the tune to play smoothly
PAUSE 1
IF endTone = 1 THEN playNextTone
next n
dr=dr+angle
stack(stackpos)=leng
stackpos=stackpos+1
leng = leng - delta
drawtree 'recursive calling itself
dr=dr-(angle * 2)
drawtree 'recursive calling itself
dr=dr+angle
stackpos=stackpos-1
leng = stack(stackpos)
oldX=newX
oldY=newY
newX=oldX - COS(RAD(dr)+3.14159)*leng
newY=oldY + SIN(RAD(dr)+3.14159)*leng
LINE oldX, oldY, newX, newY,1,cols(c)
for n = 1 to TurtleSpeed
PAUSE 1
IF endTone = 1 THEN playNextTone
next n
text stX, stY+10, time$, cm
ENDIF
END SUB

' music melodies
SUB playMelody
LOCAL AS INTEGER n
' assumes that the DATA pointer has been restored
' and the DATA ends with a pair of zeros
tonePos = 0
endMelody = 0
FOR n = 1 TO 160
READ melody(n,1), melody(n,2)
IF melody(n,1) + melody(n,2) = 0 THEN EXIT FOR
NEXT n
endTone = 1 ' ready to start playing
END SUB

SUB toneEnd
endTone = 1
END SUB

SUB playNextTone
endTone = 0
tonePos = tonePos + 1
'settick 0,0,1 'turn off the 'rest' timer
' print melody(tonePos,1),melody(tonePos,2)
if melody(tonePos,1) + melody(tonePos,2) > 0 then
play tone melody(tonePos,1),melody(tonePos,1),melody(tonePos,2),toneEnd
else
' don't re-set the end of tone flag
' just flag the end of melody
endMelody = 1
endif
end sub

' frequency, time pairs of DATA
' a zero frequency indicates a period of silence
' 0, 0 to indicate end of the melody
JingleBells:
DATA 392.0, 240.0, 659.3, 240.0, 587.3, 240.0, 523.3, 240.0
DATA 392.0, 960.0, 392.0, 240.0, 659.3, 240.0, 587.3, 240.0
DATA 523.3, 240.0, 440.0, 960.0, 440.0, 240.0, 698.5, 240.0
DATA 587.3, 28.2, 493.9, 240.0, 392.0, 240.0, 493.9, 240.0
DATA 587.3, 240.0, 784.0, 360.0, 784.0, 120.0, 698.5, 240.0
DATA 587.3, 240.0, 659.3, 960.0, 392.0, 240.0, 659.3, 240.0
DATA 587.3, 240.0, 523.3, 240.0, 392.0, 960.0, 370.0, 120.0
DATA 392.0, 240.0, 587.3, 28.2, 523.3, 240.0, 440.0, 960.0
DATA 440.0, 240.0, 698.5, 240.0, 659.3, 240.0, 587.3, 240.0
DATA 784.0, 240.0, 784.0, 120.0, 740.0, 120.0, 784.0, 120.0
DATA 740.0, 120.0, 784.0, 120.0, 830.6, 120.0, 784.0, 123.1
DATA 659.3, 240.0, 587.3, 240.0, 523.3, 480.0, 784.0, 480.0
DATA 659.3, 240.0, 659.3, 240.0, 659.3, 360.0, 622.3, 120.0
DATA 659.3, 240.0, 659.3, 240.0, 659.3, 360.0, 622.3, 120.0
DATA 659.3, 240.0, 784.0, 240.0, 587.3, 123.1, 659.3, 960.0
DATA 698.5, 240.0, 698.5, 240.0, 698.5, 360.0, 698.5, 120.0
DATA 698.5, 240.0, 659.3, 240.0, 659.3, 240.0, 659.3, 120.0
DATA 659.3, 120.0, 659.3, 240.0, 587.3, 240.0, 587.3, 240.0
DATA 659.3, 240.0, 587.3, 960.0, 0,0
' End of JingleBells

JingleBells2:
DATA 392.0, 210.0, 0.0, 30.0, 659.3, 210.0, 0.0, 30.0
DATA 587.3, 210.0, 0.0, 30.0, 523.3, 210.0, 0.0, 30.0
DATA 392.0, 840.0, 0.0, 120.0, 392.0, 210.0, 0.0, 30.0
DATA 659.3, 210.0, 0.0, 30.0, 587.3, 210.0, 0.0, 30.0
DATA 523.3, 210.0, 0.0, 30.0, 440.0, 840.0, 0.0, 120.0
DATA 440.0, 210.0, 0.0, 30.0, 698.5, 210.0, 0.0, 30.0
DATA 587.3, 24.7, 0.0, 3.5, 493.9, 210.0, 0.0, 30.0
DATA 392.0, 210.0, 0.0, 30.0, 493.9, 210.0, 0.0, 30.0
DATA 587.3, 210.0, 0.0, 30.0, 784.0, 315.0, 0.0, 45.0
DATA 784.0, 105.0, 0.0, 15.0, 698.5, 210.0, 0.0, 30.0
DATA 587.3, 210.0, 0.0, 30.0, 659.3, 840.0, 0.0, 120.0
DATA 392.0, 210.0, 0.0, 30.0, 659.3, 210.0, 0.0, 30.0
DATA 587.3, 210.0, 0.0, 30.0, 523.3, 210.0, 0.0, 30.0
DATA 392.0, 840.0, 0.0, 120.0, 370.0, 105.0, 0.0, 15.0
DATA 392.0, 210.0, 0.0, 30.0, 587.3, 24.7, 0.0, 3.5
DATA 523.3, 210.0, 0.0, 30.0, 440.0, 840.0, 0.0, 120.0
DATA 440.0, 210.0, 0.0, 30.0, 698.5, 210.0, 0.0, 30.0
DATA 659.3, 210.0, 0.0, 30.0, 587.3, 210.0, 0.0, 30.0
DATA 784.0, 210.0, 0.0, 30.0, 784.0, 105.0, 0.0, 15.0
DATA 740.0, 105.0, 0.0, 15.0, 784.0, 105.0, 0.0, 15.0
DATA 740.0, 105.0, 0.0, 15.0, 784.0, 105.0, 0.0, 15.0
DATA 830.6, 105.0, 0.0, 15.0, 784.0, 107.7, 0.0, 15.4
DATA 659.3, 210.0, 0.0, 30.0, 587.3, 210.0, 0.0, 30.0
DATA 523.3, 420.0, 0.0, 60.0, 784.0, 420.0, 0.0, 60.0
DATA 659.3, 210.0, 0.0, 30.0, 659.3, 210.0, 0.0, 30.0
DATA 659.3, 315.0, 0.0, 45.0, 622.3, 105.0, 0.0, 15.0
DATA 659.3, 210.0, 0.0, 30.0, 659.3, 210.0, 0.0, 30.0
DATA 659.3, 315.0, 0.0, 45.0, 622.3, 105.0, 0.0, 15.0
DATA 659.3, 210.0, 0.0, 30.0, 784.0, 210.0, 0.0, 30.0
DATA 587.3, 107.7, 0.0, 15.4, 659.3, 840.0, 0.0, 120.0
DATA 698.5, 210.0, 0.0, 30.0, 698.5, 210.0, 0.0, 30.0
DATA 698.5, 315.0, 0.0, 45.0, 698.5, 105.0, 0.0, 15.0
DATA 698.5, 210.0, 0.0, 30.0, 659.3, 210.0, 0.0, 30.0
DATA 659.3, 210.0, 0.0, 30.0, 659.3, 105.0, 0.0, 15.0
DATA 659.3, 105.0, 0.0, 15.0, 659.3, 210.0, 0.0, 30.0
DATA 587.3, 210.0, 0.0, 30.0, 587.3, 210.0, 0.0, 30.0
DATA 659.3, 210.0, 0.0, 30.0, 587.3, 840.0, 0.0, 120.0, 0,0
' End of JingleBells2

Jim

VK7JH
MMedit

JohnS
Guru

Joined: 18/11/2011
Location: United Kingdom
Posts: 4044

Posted: 06:31am 09 Jul 2020

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daveculp said The odd behavior is the following two things:

1. �x1 and x2 and y1 and y2 turn out to be the same and they shouldnt. �I NEVER change the value of x1 and y1. �Why is this?

I wonder if in each drawtree you need
local x2, y2

I'm not sure if you meant not to specify any types and are happy with the default.

John
Edited 2020-07-09 16:33 by JohnS

TassyJim

Guru

Joined: 07/08/2011
Location: Australia
Posts: 6283

Posted: 06:50am 09 Jul 2020

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Quote Passing Arguments by Reference
If you use an ordinary variable (ie, not an expression) as the value when calling a subroutine or a function, the
argument within the subroutine/function will point back to the variable used in the call and any changes to the
argument will also be made to the supplied variable. This is called passing arguments by reference.

CLS

drawTreeLeft(MM.HRES/2, MM.VRES,-90,10)
drawTreeRight(MM.HRES/2, MM.VRES,-90,10)

SUB drawTreeLeft (x1,y1, angle, iter)
LOCAL xx1, yy1
xx1 = x1
yy1 = y1
IF iter >0 THEN

x2 = xx1 + INT(COS( RAD(angle) ) * iter * 10.0)
y2 = yy1 + INT(SIN( RAD (angle) ) * iter * 10.0)

PRINT angle,":";xx1,yy1,":",x2,y2

LINE xx1,yy1,x2,y2,1,RGB(BROWN)

drawTreeLeft(x2,y2, angle -25, iter - 1)
REM drawTree(x2,y2, angle +25, iter - 1)
ELSE
CIRCLE x1,y1,3,1,1,RGB(GREEN), RGB(GREEN)
END IF
END SUB

SUB drawTreeRight (x1,y1, angle, iter)
LOCAL xx1, yy1
xx1 = x1
yy1 = y1
IF iter >0 THEN

x2 = xx1 +INT(( COS( RAD(angle) )) * iter * 10.0)
y2 = yy1 +INT(( SIN( RAD (angle) )) * iter * 10.0)

PRINT angle,":";xx1,yy1,":",x2,y2,"**"
LINE xx1,yy1,x2,y2,1,RGB(BROWN)

REM drawTree(x2,y2, angle -25, iter - 1)
drawTreeRight(x2,y2, angle +25, iter - 1)
ELSE
CIRCLE x1,y1,3,1,1,RGB(GREEN), RGB(GREEN)
END IF
END SUB

Jim

VK7JH
MMedit

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