Filled bezier shape?

[Trond]

Is it possible to draw a filled bezier shape (like PolyBezier_() api but filled) without brute force filling it with FillArea()? I am totally stumped in every single way possible. I do not even know how to draw a non-filled one...

[Derek]

A bit rough but it works.

Code: Select all

OpenWindow(0,0,0,800,600,"",$ca0001) 
InitSprite() 
OpenWindowedScreen(WindowID(0),0,0,800,600,0,0,0) 

*points=AllocateMemory(2*4*4) 
PokeL(*points,100);start 
PokeL(*points+4,100) 

PokeL(*points+8,300);control 
PokeL(*points+12,20) 

PokeL(*points+16,500);control 
PokeL(*points+20,580) 

PokeL(*points+24,700);end 
PokeL(*points+28,500) 
hdc=StartDrawing(ScreenOutput()) 

FrontColor(#White)
BeginPath_(hdc) 
PolyBezier_(hdc,*points,4) 
MoveToEx_(hdc,100,100,*points)
LineTo_(hdc,700,500)
SetPolyFillMode_(hdc,#ALTERNATE)
EndPath_(hdc)
FillPath_(hdc)
StopDrawing() 

Repeat 
Until WaitWindowEvent()=16 

[Trond]

I'm interested in the algorithm behind it, so API won't work.

[Derek]

Ah right, I thought you just wanted the end result.

[Fluid Byte]

What is "brute force filling"?

[Trond]

It means, that you just draw the shape, and then use FillArea() inside it. FillArea() is dumb and simply fills pixels until it encounters a border. I imaginged the correct way to do it was to use maths to calculate whether a pixel should be coloured or not.

[Christian H]

Code: Select all

*points=AllocateMemory(2*4*4) 

Why AllocateMemory

Code: Select all

OpenWindow(0,0,0,800,600,"",$ca0001) ;  $ca0001?
InitSprite()
OpenWindowedScreen(WindowID(0),0,0,800,600,0,0,0)

Dim points.Point(4)

points(0)\x = 100 ;start
points(0)\y = 100

points(1)\x = 300 ;control
points(1)\y =  20

points(2)\x = 500 ;control
points(2)\y = 580

points(3)\x = 700 ;end
points(3)\y = 500


hdc=StartDrawing(ScreenOutput())

FrontColor(#White)
BeginPath_(hdc)
PolyBezier_(hdc,@points(),4)
MoveToEx_(hdc,100,100,@points())
LineTo_(hdc,700,500)
SetPolyFillMode_(hdc,#ALTERNATE)
EndPath_(hdc)
FillPath_(hdc)
StopDrawing()

Repeat
Until WaitWindowEvent() = #PB_Event_CloseWindow

[Derek]

Just the way I did it. Different strokes.

Also $ca0001 is just short for #PB_Window_ScreenCentered|#PB_Window_SystemMenu|#PB_Window_MinimizeGadget

[pdwyer]

Ah right, I thought you just wanted the end result.

No, he just want's to know if it's possible!

There's some good examples here http://en.wikipedia.org/wiki/B%C3%A9zier_curve which have animations on them being produced. This might help get your mind around the idea.