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DarkBASIC Professional Discussion / Line Function

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Libervurto

Years of Service

User Offline

Joined: 30th Jun 2006

Location: On Toast

Posted: 9th Jun 2013 08:42

Link

I found quite an elegant method for drawing lines.

+ Code Snippet

sync on
sync rate 20
sw = screen width()
sh = screen height()

do
	a = rnd(6)+1
	col = ((a&&1) + (a&&2)*256 + (a&&4)*65536) * 255
	ink col,0
	ligne(rnd(sw),rnd(sh),rnd(sw),rnd(sh))
	sync
loop
end

function ligne(ax,ay,bx,by)
	dx as float
	dy as float
	u as float
	t as float

	dx = abs(ax-bx)
	dy = abs(ay-by)
	if dx > dy then u = 1.0/dx else u = 1.0/dy
	
	for t = 0 to 1.0 step u
		x = round( (1.0-t)*ax + t*bx )
		y = round( (1.0-t)*ay + t*by )
		dot x,y
	next t
endfunction

function round(x#)
	x = x# + x# - int(x#)
endfunction x

Here's the function again, a bit more compact and with internal rounding:

+ Code Snippet

function ligne(ax,ay,bx,by)
	dx# = abs(ax-bx) :	dy# = abs(ay-by)
	if dx# > dy# then u# = 1.0/dx# else u# = 1.0/dy#
	
	for t# = 0 to 1.0 step u#
		x# = (1.0-t#)*ax + t#*bx
		y# = (1.0-t#)*ay + t#*by
		x = x# + x# - int(x#)
		y = y# + y# - int(y#)
		dot x,y
	next t
endfunction

The difficulty in learning is not acquiring new knowledge but relinquishing the old.

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Burning Feet Man

Years of Service

User Offline

Joined: 4th Jan 2008

Location: Sydney, Australia

Posted: 9th Jun 2013 12:42 Edited at: 9th Jun 2013 12:46

Link

I see your line function, and I raise you my line function

Note that you'll need Advanced 2D DLL to run my function.

Pos_X & Pos_Y are the starting point, then simply state your length and in what angle you'd like to draw. Centre is a toggle, that when active, Pos_X & Pos_Y will be the centre of the line. Pretty cool eh?

+ Code Snippet

Function Draw_Line_Direction(Pos_X, Pos_Y, Length, Angle,Centre, Colour)
	If Centre = 0
		A2line Pos_X, Pos_Y, Pos_X + (length*Sin(angle)), Pos_Y+(length*Cos(Angle))*-1 , Colour
	else
		A2line Pos_X, Pos_Y, Pos_X + ((length*0.5)*Sin(angle))*-1, Pos_Y+((length*0.5)*Cos(Angle)),  Colour
		A2line Pos_X, Pos_Y, Pos_X + ((length*0.5)*Sin(angle)), Pos_Y+((length*0.5)*Cos(Angle))*-1,  Colour
	Endif
Endfunction

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DarkBASIC Professional Discussion / Line Function