3D Curved lines

Blitz3D Forums/Blitz3D Programming/3D Curved lines

wmaass

(Posted 2009) [#1]

I want to draw the trajectory of a golf ball as a smooth 3D line. Any idea how one would do this? Example below.

Ross C

(Posted 2009) [#2]

You would probably need some kind of 3d line draw first off, and also, a way to break the line into points, to assign your vertices co-ords.

Creating the 3d line is fairly easy, however, i'm not much on curve maths, sorry...

wmaass

(Posted 2009) [#3]

I see several 3d Line functions like the one below by Fredborg. I suppose I could use this but would need lots of points to get a smoothish line.

Function Line3D(mesh,x0#,y0#,z0#,x1#,y1#,z1#) 

	If mesh = 0 
		mesh = CreateMesh() 
		surf = CreateSurface(mesh) 
		EntityFX mesh,1+16 
	Else 
		lastsurf = CountSurfaces(mesh)
		surf = GetSurface(mesh,lastsurf)
		If CountVertices(surf)>30000
			surf = CreateSurface(mesh)
		EndIf 
	End If 

	v0 = AddVertex(surf,x0,y0,z0) 
	v1 = AddVertex(surf,x1,y1,z1)  
	v2 = AddVertex(surf,(x0+x1)*0.5,(y0+y1)*0.5,(z0+z1)*0.5) 
	AddTriangle surf,v0,v1,v2 

	Return mesh 

End Function

stayne

(Posted 2009) [#4]

Check this out...

http://filax.celeonet.fr/_fofo/index.php?PHPSESSID=36ea6fb45eec2fed81c8f65c2f09b77f&topic=3004.0

Sadly I think the backslashes were stripped out of the code.

wmaass

(Posted 2009) [#5]

That's interesting, but as you said it's mangled.

stayne

(Posted 2009) [#6]

Yeah sadly. I thought Draw3D could do 3D lines?

FlagDKT

(Posted 2009) [#7]

U need bezier interpolation + linedrawing routine

wmaass

(Posted 2009) [#8]

There is a good 3d bezier curve lib in the archives. I might try tinkering with that. This is just for a prototype so I could just texture some quads with the 2d trajectories with alpha. Not ideal but would demonstrate the idea.

Stevie G

(Posted 2009) [#9]

You don't need bezier - you need to actually calculate the trajectory based on initial velocity, gravity and various other factors depending on how accurate you want it. The bog standard physics functions below will help.

S = UT + .5 * T^2
D = S * T

Store the X & Y coords and then draw the 3d-lines between them.

wmaass

(Posted 2009) [#10]

So theoretically I could store the x,y,z coords and use the function in my second post to draw lines between them. Looks like I'll be bust this evening, thanks Stevie G.