Help Needed with 3D accelerated 2D lines

Blitz3D Forums/Blitz3D Programming/Help Needed with 3D accelerated 2D lines

TartanTangerine (was Indiepath)

(Posted 2004) [#1]

I've written this code to emulate the 2d Line function using single surface triangles. The code works great as long as the origin of the line is 0,0. If I change the origin it all goes a bit "Pete Tong".

Can anyone help? I also want the origin to map on to the normal 2d co-ords, ie. 0,0 = Top Left.

Thanks in advance.

Graphics3D 800,600,32,2

texsize = 64

LineTex = CreateTexture(texsize,texsize,2)
SetBuffer TextureBuffer(LineTex)
Line 0,0,0,texsize-1
SetBuffer BackBuffer()

cam = CreateCamera()
CameraProjMode cam,2
CameraZoom cam,0.1
SeedRnd MilliSecs()


blob = line3d(0,0,0,30,30,1)

EntityColor blob,0,255,255
EntityBlend blob,3
EntityTexture blob,LineTex

For x = 0 To 100
  blob = line3d(blob,0,0,Rnd(-400,400),Rnd(-300,300),Rnd(0.1,0.9))
Next


;WireFrame 1

While Not KeyHit(1)

	If Not MouseDown(1) Then TurnEntity blob,0,0,.1

	RenderWorld

	Text 0,0,TrisRendered()
	
	Flip ;False


Wend


Function Line3D(Mesh,x0#,y0#,x1#,y1#,thickness#=0.5) 

	
	pivot = CreatePivot()
	PositionEntity pivot,x0,y0,10
	rot# = ATan2(y1-y0,x1-x0)  ; how much to rotate the quad to get the right angle.
	TurnEntity pivot,0,0,rot

	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 
	
		
	dx# = Abs(x1-x0)
	dy# = Abs(y1-y0)
	
	length# = Sqr((dx*dx)+(dy*dy))
	
	sizex# = length/120 : sizeY# = thickness  
	
	TFormPoint 0,0,0,Pivot,0
	V = AddVertex(Surf,TFormedX(),TFormedY(),TFormedZ(),0,0)
										
	TFormPoint SizeX*3,0,0,Pivot,0
	AddVertex(Surf,TFormedX(),TFormedY(),TFormedZ(),0,0.9)
				
	TFormPoint 0,-SizeY*3,0,Pivot,0
	AddVertex(Surf,TFormedX(),TFormedY(),TFormedZ(),0.9,0.9)
						
	AddTriangle Surf,V,V+1,V+2
	FreeEntity pivot
	Return Mesh 

End Function

Stevie G

(Posted 2004) [#2]

I have adapted that for better 3d lines - may help.

Function Line3d( mesh, x0#,z0#,x1#,z1#, y# , r, g, b)

	If mesh = 0 
		mesh = CreateMesh() 
		surf = CreateSurface(mesh) 
	Else 
		surf = GetSurface(mesh,1)
		If CountVertices(surf)>30000
			surf = CreateSurface(mesh)
		EndIf 
	End If 

	dx# = x1 - x0
	dz# = z1 - z0
	d# = Sqr( dx*dx + dz*dz ) * 4.0
	dx = dx / d
	dz = dz / d

	v0 = AddVertex( surf , x0-dz,  z0+dx , y )
	v1 = AddVertex( surf, x1-dz, z1 + dx, y )
	v2 = AddVertex( surf, x1+dz, z1 - dx, y )
	v3 = AddVertex( surf, x0 + dz, z0 - dx , y )
	
	For v = v0 To v3
		VertexColor surf, v, r,g, b
	Next
		
	AddTriangle surf,v0,v1,v2 
	AddTriangle surf,v2,v3,v0

        entityfx mesh,2
	Return mesh 

End Function

TartanTangerine (was Indiepath)

(Posted 2004) [#3]

Your the man. I always make it too complicated :)