Michael Hartlef
26-12-2009, 15:18
Here is a little sample code, to produce a catmull-rom spline with TBGL. This algorythm will be used to add another variaty to create a path in the next update of TBAI.
'*********************************************************
'
' catmull_rom_spline interpretation for thinBasic
' by Michael Hartlef
'
'*********************************************************
Uses "TBGL"
Type point
x As Single
y As Single
End Type
%numPoints = 6
Dim pa(%numPoints) As point
Global width, height As Long
'*********************************************************
Function TBMAIN()
'*********************************************************
Local hWnd As DWord
' -- Create and show window
hWnd = TBGL_CREATEWINDOWEX("TBGL catmull-rom spline script - press Q to quit, P to calculate a new curve", 640, 480, 32, %TBGL_WS_WINDOWED Or %TBGL_WS_CLOSEBOX)
TBGL_GETWINDOWCLIENT( hWnd, width, height )
SetupPoints()
TBGL_SHOWWINDOW
' -- Resets status of all keys
TBGL_RESETKEYSTATE()
' -- Set the resolution and the coordinate system
TBGL_RENDERMATRIX2D (0,height,width,0)
' -- Main loop
While TBGL_ISWINDOW(hWnd)
' -- clear the background
TBGL_CLEARFRAME
' -- Draw the line
DrawSpline()
' -- Flip the framebuffer
TBGL_DRAWFRAME
' -- Q key to exit application
If TBGL_GETWINDOWKEYSTATE(hWnd, %VK_Q) Then Exit While
If TBGL_GETWINDOWKEYONCE(hWnd,%VK_P) Then SetupPoints()
Wend
TBGL_DESTROYWINDOW
End Function
'*********************************************************
Sub GetPointOnSpline(pn As point, t As Single, p0 As point, p1 As point, p2 As point, p3 As point)
'*********************************************************
Local t2,t3 As Single
t2 = t * t
t3 = t2 * t
pn.x = 0.5 * ( ( 2.0 * p1.x ) + ( -p0.x + p2.x ) * t + ( 2.0 * p0.x - 5.0 * p1.x + 4 * p2.x - p3.x ) * t2 + ( -p0.x + 3.0 * p1.x - 3.0 * p2.x + p3.x ) * t3 )
pn.y = 0.5 * ( ( 2.0 * p1.y ) + ( -p0.y + p2.y ) * t + ( 2.0 * p0.y - 5.0 * p1.y + 4 * p2.y - p3.y ) * t2 + ( -p0.y + 3.0 * p1.y - 3.0 * p2.y + p3.y ) * t3 )
End Sub
'*********************************************************
Sub SetupPoints()
'*********************************************************
Local i As Long
For i = 1 To %numPoints
pa(i).x = i*width/(%numPoints+1)
pa(i).y = Rnd(50,height-50)
Next
End Sub
'*********************************************************
Sub DrawSpline()
'*********************************************************
Local i As Long
Local dt As Single
Local dp As point
Local div As Long = 50
' -- Draw the curve
TBGL_COLOR 255,255,255
For i = 1 To div
dt = i/div
GetPointOnSpline(dp, dt, pa(1), pa(1), pa(2), pa(3))
TBGL_POINT(dp.x, dp.y)
GetPointOnSpline(dp, dt, pa(1), pa(2), pa(3), pa(4))
TBGL_POINT(dp.x, dp.y)
GetPointOnSpline(dp, dt, pa(2), pa(3), pa(4), pa(5))
TBGL_POINT(dp.x, dp.y)
GetPointOnSpline(dp, dt, pa(3), pa(4), pa(5), pa(6))
TBGL_POINT(dp.x, dp.y)
GetPointOnSpline(dp, dt, pa(4), pa(5), pa(6), pa(6))
TBGL_POINT(dp.x, dp.y)
Next
' -- Draw some red points for the six points of the curve
TBGL_COLOR 255,0,0
For i = 1 To %numPoints
TBGL_NGON(pa(i).x, pa(i).y, 5,16)
Next
End Sub
'*********************************************************
'
' catmull_rom_spline interpretation for thinBasic
' by Michael Hartlef
'
'*********************************************************
Uses "TBGL"
Type point
x As Single
y As Single
End Type
%numPoints = 6
Dim pa(%numPoints) As point
Global width, height As Long
'*********************************************************
Function TBMAIN()
'*********************************************************
Local hWnd As DWord
' -- Create and show window
hWnd = TBGL_CREATEWINDOWEX("TBGL catmull-rom spline script - press Q to quit, P to calculate a new curve", 640, 480, 32, %TBGL_WS_WINDOWED Or %TBGL_WS_CLOSEBOX)
TBGL_GETWINDOWCLIENT( hWnd, width, height )
SetupPoints()
TBGL_SHOWWINDOW
' -- Resets status of all keys
TBGL_RESETKEYSTATE()
' -- Set the resolution and the coordinate system
TBGL_RENDERMATRIX2D (0,height,width,0)
' -- Main loop
While TBGL_ISWINDOW(hWnd)
' -- clear the background
TBGL_CLEARFRAME
' -- Draw the line
DrawSpline()
' -- Flip the framebuffer
TBGL_DRAWFRAME
' -- Q key to exit application
If TBGL_GETWINDOWKEYSTATE(hWnd, %VK_Q) Then Exit While
If TBGL_GETWINDOWKEYONCE(hWnd,%VK_P) Then SetupPoints()
Wend
TBGL_DESTROYWINDOW
End Function
'*********************************************************
Sub GetPointOnSpline(pn As point, t As Single, p0 As point, p1 As point, p2 As point, p3 As point)
'*********************************************************
Local t2,t3 As Single
t2 = t * t
t3 = t2 * t
pn.x = 0.5 * ( ( 2.0 * p1.x ) + ( -p0.x + p2.x ) * t + ( 2.0 * p0.x - 5.0 * p1.x + 4 * p2.x - p3.x ) * t2 + ( -p0.x + 3.0 * p1.x - 3.0 * p2.x + p3.x ) * t3 )
pn.y = 0.5 * ( ( 2.0 * p1.y ) + ( -p0.y + p2.y ) * t + ( 2.0 * p0.y - 5.0 * p1.y + 4 * p2.y - p3.y ) * t2 + ( -p0.y + 3.0 * p1.y - 3.0 * p2.y + p3.y ) * t3 )
End Sub
'*********************************************************
Sub SetupPoints()
'*********************************************************
Local i As Long
For i = 1 To %numPoints
pa(i).x = i*width/(%numPoints+1)
pa(i).y = Rnd(50,height-50)
Next
End Sub
'*********************************************************
Sub DrawSpline()
'*********************************************************
Local i As Long
Local dt As Single
Local dp As point
Local div As Long = 50
' -- Draw the curve
TBGL_COLOR 255,255,255
For i = 1 To div
dt = i/div
GetPointOnSpline(dp, dt, pa(1), pa(1), pa(2), pa(3))
TBGL_POINT(dp.x, dp.y)
GetPointOnSpline(dp, dt, pa(1), pa(2), pa(3), pa(4))
TBGL_POINT(dp.x, dp.y)
GetPointOnSpline(dp, dt, pa(2), pa(3), pa(4), pa(5))
TBGL_POINT(dp.x, dp.y)
GetPointOnSpline(dp, dt, pa(3), pa(4), pa(5), pa(6))
TBGL_POINT(dp.x, dp.y)
GetPointOnSpline(dp, dt, pa(4), pa(5), pa(6), pa(6))
TBGL_POINT(dp.x, dp.y)
Next
' -- Draw some red points for the six points of the curve
TBGL_COLOR 255,0,0
For i = 1 To %numPoints
TBGL_NGON(pa(i).x, pa(i).y, 5,16)
Next
End Sub