Remove vertex? (clean mesh)

Hi all,

If I create two cubes and place them right next to each other on the x-axis (one is a child of the other), is it possible to weld the two shapes together by identifying the overlapping vertices and removing one of them?

I didn't see a 'delete vertex' command when I was browsing the docs, sorry if I missed it!

Basically in my editor I place a load of meshes then save them out as a single mesh for collision, but there are times when I place one wall next to another, and there are 'extra' poly/verts where two shapes overlay exactly, so for performace I'd like to detect and remove these for more geometrically sound models.

Thoughts welcome!

Cheers,
LW.

Maybe you could create a function that copies the whole surface without without those vertices

There isn't a 'delete vertex' command. To delete a vertex you must manually rebuild the entire mesh, sans-aforementioned vertex.

If you want to weld vertices then you should do it the same way 3DS Max etc does it; i.e. with proximity checks between each vertex.

use ClearSurface Surface,true
=> It cleans ALL vertices within the surface.
The way to weld vertex together :
( according, you 'll maybe weld two vertices with different UV ... so take car what you expect ^^ )
+> Copy vertices into array/Types etc... ( copy infos : Coords,Normals,UV, Color )
+> Copy triangle into an array
copy the 3 TriangleVertex(Surfave,Triangle,0/1/2)

Clearsurface Surface,True,True => it will "delete" every vertices and every triangles.

+> rebuild surface using the stored array.
Take care with the Id you'll use too rebuild, according you deleted some one those ^^

Thanks, looks like this is going to be possible with some work.

Cheers,
LW.

Entityalpha StevieG, 1

@ LamptonWorm,

I have a function which I use for this very purpose. Code and example below. Note that the function expects the mesh which is passed to be unwelded.

Graphics3D 640,480,16,1

Global LIGHT = CreateLight()
Global CUBE = MESHcull( CreateCube() , C_Top+C_Right )
EntityFX CUBE, 4

Global CAMERA = CreateCamera()
PositionEntity CAMERA, 0,5,-10
PointEntity CAMERA, CUBE


Const C_Front = 1
Const C_Rear = 4
Const C_Left = 8
Const C_Right = 2
Const C_Top = 16
Const C_Bottom = 32

While Not KeyDown(1)

	TurnEntity CUBE, 0,1,0 ;1,0,1
	RenderWorld()
	Flip

Wend

;=====================================================================================
;=====================================================================================
;=====================================================================================

Function MESHcull( Mesh , Flags = 0 )

	If Flags = 0 Return Mesh

	copy = CopyMesh( Mesh )
	s = GetSurface( copy, 1 )
	
	Cs = GetSurface( mesh , 1 )
	ClearSurface Cs, 1, 1

	For t = 0 To CountTriangles( s )-1
		;calculate triangle normal
		v0 = TriangleVertex( s, t, 0 )
		v1 = TriangleVertex( s, t, 1 )
		v2 = TriangleVertex( s, t, 2 )
		ax# = VertexX( s, v1 ) - VertexX( s, v0 )
		ay# = VertexY( s, v1 ) - VertexY( s, v0 )	
		az# = VertexZ( s, v1 ) - VertexZ( s, v0 )	
		bx# = VertexX( s, v2 ) - VertexX( s, v1 )
		by# = VertexY( s, v2 ) - VertexY( s, v1 )	
		bz# = VertexZ( s, v2 ) - VertexZ( s, v1 )	
		Nx# = ( ay * bz ) - ( az * by )
		Ny# = ( az * bx ) - ( ax * bz )
		Nz# = ( ax * by ) - ( ay * bx )
		Ns# = Sqr( Nx * Nx + Ny*Ny + Nz*Nz )
		Nx = Nx / Ns
		Ny = Ny / Ns
		Nz = Nz / Ns
				
		OK = True
		For l = 0 To 5
			Flag = 2^l
			If ( Flags And Flag) = Flag
				;determine plane normal
				Select Flag
					Case C_Front	px# = 0  : py# = 0  : pz# = 1	
					Case C_Rear		px# = 0  : py# = 0  : pz# = -1	
					Case C_Left		px# = -1 : py# = 0  : pz# = 0	
					Case C_Right	px# = 1  : py# = 0  : pz# = 0	
					Case C_Top		px# = 0  : py# = 1  : pz# = 0	
					Case C_Bottom	px# = 0  : py# = -1 : pz# = 0	
				End Select
				If Nx = Px And Ny = Py And Nz = Pz OK = False
			EndIf
		Next
								
		If OK
			nv0 = AddVertex( Cs, VertexX( s , v0 ) , VertexY( s, v0 ) , VertexZ( s, v0 ) )
			nv1 = AddVertex( Cs, VertexX( s , v1 ) , VertexY( s, v1 ) , VertexZ( s, v1 ) )
			nv2 = AddVertex( Cs, VertexX( s , v2 ) , VertexY( s, v2 ) , VertexZ( s, v2 ) )
			VertexNormal Cs , nv0 , Nx, Ny, Nz
			VertexNormal Cs , nv1 , Nx, Ny, Nz
			VertexNormal Cs , nv2 , Nx, Ny, Nz
			AddTriangle( Cs , nv0, nv1, nv2 )
		EndIf
		
	Next
		
	FreeEntity copy
	Return Mesh
		
End Function		

Entityalpha StevieG, 0

lmao @ stevie

Your collision responce is still being processed. Best watch yourself.

Oh wait, your making yourself visible. I see. :oS

HideEntity RossC

Thanks Stevie G, I'll have a play.

Cheers,
LW.

I'm trying to understand this function StevieG. Is it a function that deals with cubes only?

Cheers, and thanks for any detail on the workings.

The cube just looks like a test mesh.
The function copies the original mesh, iterates through all tris, and then returns the newly processed mesh.

It can deal with other shapes but can only cull triangles which have face normals which exactly match one of the 6 culling normals. So, for example if you created a cylinder and wanted to remove the bottom triangles only you would have to apply an unweld function which combines the cylinder into one surface ( blitz normally creates 2 x surfaces ) and then call MESHcull( cyclinder, C_Bottom ). I use it to build meshes in code and remove triangles which aren't seen.

Big10p has a function in the archives which culls triangles based on a rotated plane which would probably be better for you.

Stevie