' Lissajous loop program from Bleep - Modified for Famebuffer Sync

Option ANGLE DEGREES
FRAMEBUFFER CREATE
FRAMEBUFFER LAYER

FRAMBUFFER MERGE 0,b '<===== Setup backcround merge

RX=MM.HRES:RY=MM.VRES:CX=RX\2:CY=RY\2
Scale=0.95: AX=CY*Scale: AY=CY*Scale
Dim Integer i,j,a=1: b=0: p=0: f=0: c=0
Dim Integer sx(360),ex(360),sy(360),ey(360)
'4 arrays & Background Merge @ 376MHz 35mS/loop or (45mS reduced flicker)
FRAMEBUFFER WRITE F '<===== Write the following to Layer F
CLS 0'<========= Black is the default transparent colour
Colour RGB(Blue),0 '<== choose graticule colour from the RGB121 palette
RBox 0,0,RX,RY,10,,RGB(Myrtle) '<=========== choose Background Colour
For y=80 To RY Step 80
For x= 8 To RX Step  8
Pixel x,y
Next x:Next y
For x=80 To RX Step 80
For y= 8 To RY Step  8
Pixel x,y
Next y:Next x
For y=0 To RY Step 8
Line CX+1,y,CX-1,y
If Not (y Mod 40) Then Line CX+2,y,CX-2,y
If Not (y Mod 80) Then Line CX+3,y,CX-3,y
Next y
For x=0 To RX Step 8
Line x,CY+1,x,CY-1
If Not (x Mod 40) Then Line x,CY+2,x,CY-2
If Not (x Mod 80) Then Line x,CY+3,x,CY-3
Next x
Triangle CX,0,CX-3,8,CX+3,8,,1
Triangle RX,CY,RX-8,CY-3,RX-8,CY+3,,1
FRAMEBUFFER WRITE L '<===== Write the following to Layer L
Do
Timer =0
If p>360 Then p=0: EndIf
If b>6   Then a=a+1: b=0: c=0: EndIf
If a>5   Then a=1:   b=0: c=0: EndIf
If c=50  Then
f=1
If a=Fix(b) Then f=0: c=0: EndIf
EndIf
If c=130 Then f=0: c=0: EndIf
'calculate the x and y start points
 sx(0)= AX * Sin(p) + CX
 sy(0)= AY * Sin(p) + CY
'calculate all remaining points
For i= 0 To 360
 ex(i) = AX * Sin(a*i + p) + CX
 ey(i) = AY * Sin(b*i + p) + CY
Next i
'Copy whole arrays,(0 to 360 less 1) offset by one Integer
Memory copy integer Peek(varaddr ex(0)),Peek(varaddr sx(1)),360
Memory copy integer Peek(varaddr ey(0)),Peek(varaddr sy(1)),360

FRAMEBUFFER SYNC ' <==== Wait until previous write complete

'Pause 11 'prevents screen flicker because Backgroung Merge not finished.
CLS 0 'Re-draw the whole screen
'Draw all 360 lines from array
Line sx(),sy(),ex(),ey(),,RGB(Yellow) '<= choose Foreground Colour for plot
FRAMEBUFFER MERGE 0,b '<======== copy both layers to the screen
Inc p: Inc c
If  f=0 Then b=b+.02
Print Timer
Loop until inkey$<>""
end