Abandoned

Function Quad(x0,y0,x1,y1,x2,y2,x3,y3,mode=0) ;mode=1 draws twice, slower mode=0 draws once, slow. recommend use 0
Tri(x0,y0,x1,y1,x2,y2)
Tri(x0,y0,x2,y2,x3,y3)
If mode=1
	Tri(x2,y2,x0,y0,x1,y1)
	Tri(x1,y1,x3,y3,x2,y2)
EndIf
End Function

Function Tri(x0,y0,x1,y1,x2,y2)
	xval(0)=x0
	yval(0)=y0
	xval(1)=x1
	yval(1)=y1
	xval(2)=x2
	yval(2)=y2
	FastPoly(3)
End Function

Function FastPoly(vcount)

	RGBColor = ColorBlue() Or (ColorGreen() Shl 8) Or (ColorRed() Shl 16) Or ($ff000000)

	; get clipping region
	width=GraphicsWidth()
	height=GraphicsHeight()
	
	; find top verticy
	b=vcount-1
	y=yval(0)
	While c<>b
		c=c+1
		yy=yval(c)
		If yy<y y=yy d=c
	Wend
	c=d 
	t=c

	; draw top to bottom
	While y<height
		
		; get left gradient
		If y=yval(c)
			While y=yval(c)
				x0=xval(c) Shl 16
				c=c+1
				If c>b c=a
				If c=t Goto Finish
				If y>yval(c) Goto Finish
			Wend
			h=yval(c)-y
			g0=((xval(c) Shl 16)-x0)/h
		EndIf

		; get right gradient
		If y=yval(d)
			While y=yval(d)
				x1=xval(d) Shl 16
				d=d-1
				If d<a d=b
				If y>yval(d) Goto Finish
			Wend
			h=yval(d)-y
			g1=((xval(d) Shl 16)-x1)/h
		EndIf

		; calc horizontal span
		x=x1 Sar 16
		w=((x0 Sar 16)-x)+1

		; draw down to next vert
		If (w > 0) And (y > -1) And (x < width) And ((x+w) > 0)
	
			;crop left
			If x < 0 
				w=w+x
				x=0		
			EndIf
			
			;crop right
			If (x+w) > width
				w=width-x
			EndIf	
			
			; Draw scanline.
			For Lx = x To (x+w)
				WritePixelFast Lx, y, RGBColor
			Next
			
		EndIf
		
		; next	
		x0=x0+g0
		x1=x1+g1
		y=y+1
		
	Wend

	.Finish
	
End Function