3d lines

This code has been declared by its author to be Public Domain code.

3d lines by koekjesbaby

2003

this code generates a mesh of 0 units thick. it first renders the normal geometry, then sets the rendermode to wireframe and hides the normal geometery (hiding or showing the lines is not necessary since they only show up in wireframe mode) to finally render te wireframe (lines) without updating the zbuffer or clearing the cameracolor.

theoretically this should render hardware acellerated lines that can have alpha, appear behind and in front of alpha'ed objects, can have textures (dashed lines anyone?) or: can have every property an entity can have.

have fun!

Function createline(x1#,y1#,z1#, x2#,y2#,z2#, mesh=0)
	
	If mesh = 0 Then 
		mesh=CreateMesh()
		EntityFX(mesh,16)
		surf=CreateSurface(mesh)	
		verts = 0	
	
		AddVertex surf,x1#,y1#,z1#,0,0
	Else
		surf = GetSurface(mesh,1)
		verts = CountVertices(surf)-1
	End If
	
	AddVertex surf,(x1#+x2#)/2,(y1#+y2#)/2,(z1#+z2#)/2,0,0 
	; you could skip creating the above vertex and change the line below to
	; AddTriangle surf,verts,verts+1,verts+0
	; so your line mesh would use less vertices, the drawback is that some videocards (like the matrox g400)
	; aren't able to create a triangle with 2 vertices. so, it's your call :)
	AddVertex surf,x2#,y2#,z2#,1,0
	
	AddTriangle surf,verts,verts+2,verts+1
	
	Return mesh
End Function

; --- set graphics
Graphics3D 640,480,32,0
SetBuffer(BackBuffer())

; --- create scene setup
camPiv = CreatePivot()
camera = CreateCamera(camPiv)
PositionEntity(camera, 0,0,-10)

light=CreateLight(2) 
PositionEntity(light,4,10,0) 
LightRange(light,10)

; --- create test cube
cube=CreateCube()
ScaleMesh(cube, 2,1,1)
EntityAlpha(cube, 0.5)
cube2=CreateCube()
ScaleMesh(cube2, 1.8,0.8,0.8)

; --- create lines
lines = createLine(2,1,1,    1,2,1)
lines = createLine(1,2,1,    0,2.3,1, lines)
lines = createLine(0,2.3,1, -1,2,1, lines)
lines = createLine(-1,2,1,  -2,1,1, lines)
EntityColor(lines, 255,0,0)

; okay, this is a bit cheating and very wrong/memory leak prone and shouldn't be used this way
; but i wanted to show more than one Line quickly

lines = createLine(2,1,-1,    1,2,-1)
lines = createLine(1,2,-1,    0,2.3,-1, lines)
lines = createLine(0,2.3,-1, -1,2,-1, lines)
lines = createLine(-1,2,-1,  -2,1,-1, lines)
EntityColor(lines, 255,0,0)

lines = createLine(-3,1,1,   3,1,1)
EntityColor(lines, 255,0,0)
lines = createLine(-5,1,-1,  4,1,-1)
EntityColor(lines, 255,0,0)
lines = createLine(-4,-1,1,  3,-1,1)
EntityColor(lines, 255,0,0)
lines = createLine(-3,-1,-1, 5,-1,-1)
EntityColor(lines, 255,0,0)

TurnEntity(campiv, 35,35,35)

While Not KeyHit(1)

	; --- camera controls
	scrollwheel = MouseZSpeed()
	If MouseDown(1) Then 
		TurnEntity(camPiv, MouseYSpeed(),-MouseXSpeed(),0)
	Else If scrollwheel <> 0 Then 
		MoveEntity(camera, 0,0,scrollwheel*3)
	Else
		dummy = MouseYSpeed():dummy = MouseXSpeed():dummy = MouseZSpeed() ; prevent mousespeed blips.
	End If

	; --- rendering
	CameraClsMode(camera, 1, 1)
	WireFrame(0)
	ShowEntity(cube)
	ShowEntity(cube2)	
	RenderWorld()
	
	CameraClsMode(camera, 0, 0)
	WireFrame(1)
	HideEntity(cube)
	HideEntity(cube2)	
	RenderWorld()

	; or try this:
	;CameraClsMode(camera, 1, 1)
	;WireFrame(1)
	;HideEntity(cube)
	;HideEntity(cube2)	
	;RenderWorld()
	
	;CameraClsMode(camera, 0, 0)
	;WireFrame(0)
	;ShowEntity(cube)
	;ShowEntity(cube2)	
	;RenderWorld()
	Flip()
Wend

End

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