'Fractal.sb modified to debug and trap some of the spurious pixels seen.
GraphicsWindow.BackgroundColor = "Black"
x = 100
y = 100
oldx = 150
oldy = 1000
'For i = 1 To 100000
For i = 1 To 100000
r = Math.GetRandomNumber(3)
' r determines whether the top, bottom left or bottom right sub-triangle
' of the overall triangle is selected. I have used the value of r to change
' the pixel colour to determine this fact.
' You will probably need to stretch the window to see the red and blue pixels.
'line goes from 30,1000 to 150,30
'gradient = (30 - 1000) / (150 - 30) = - 970 / 120 = -97 / 12
'origin = 30,1000
'y = -97/12 * x + 1242.5 from y=mx+c knowing two co-ordinates
'x = 30, y = 1000 and x = 150, y = 30
ux = 150
uy = 30
If (r = 1) then
ux = 30
uy = 1000
EndIf
If (r = 2) Then
ux = 1000
uy = 1000
EndIf
x = (x + ux) / 2
y = (y + uy) / 2
If x < oldx Then
oldx = x
' TextWindow.WriteLine("oldx = " + oldx)
EndIf
If y < oldy Then
oldy = y
' TextWindow.WriteLine("oldy = " + oldy)
EndIf
If r=1 Then
GraphicsWindow.SetPixel(x,y,"red")
' TextWindow.WriteLine("red pixel")
EndIf
If r=2 Then
GraphicsWindow.SetPixel(x,y,"Blue")
EndIf
If r=3 Then
testy = (x * -97/12) + 1242.5
If testy > y Then
' Trap a pixel to the left of the large green triangle
' Does not trap any other stray pixels.
TextWindow.Write("x = " + x)
TextWindow.Write(" y = " + y)
TextWindow.WriteLine(" testy = " + testy)
EndIf
GraphicsWindow.SetPixel(x,y,"LightGreen")
EndIf
EndFor
Program Listing: HRD467