Manual mesh vs normals

Blitz3D Forums/Blitz3D Programming/Manual mesh vs normals

silentworks

(Posted 2012) [#1]

Hi,

I am trying to create a simple floor mesh, and calling updatenormals to calculate the normal vectors, but it seems I am doing something wrong. There is no "light effect" when using this mesh and a point light.

Does UpdateNormals suppose to calculate the normals or did I misread something? :-\

Thanks.

Function CreateFloor(DoubleSided = 1)

	Mesh = CreateMesh()
	Surface = CreateSurface(Mesh)

	AddVertex(Surface, -1, 0, -1, 0, 0)
	AddVertex(Surface, 1, 0, -1, 1, 0)
	AddVertex(Surface, -1, 0, 1, 0, 1)
	AddVertex(Surface, 1, 0, 1, 1, 1)

	AddTriangle(Surface, 0, 1, 2)
	AddTriangle(Surface, 1, 3, 2)
	
	If DoubleSided
		AddTriangle(Surface, 0, 2, 1)
		AddTriangle(Surface, 1, 2, 3)
	EndIf

	UpdateNormals Mesh
	Return Mesh
	
End Function

Floyd

(Posted 2012) [#2]

UpdateNormals considers all vertices at a single point in space to be the same vertex. There would be a proper normal for either side. But they point in exactly the opposite direction. So adding everything together gives a grand total of zero. Thus all normals will be zero.

Your vertices all have y=0, so the floor is horizontal. Thus all normals are vertical and you can skip UpdateNormals. Just manually set every normal to (0,1,0).

silentworks

(Posted 2012) [#3]

Thanks!

Indeed, VertexNormal does the trick. :)

Function CreateFloor(DoubleSided = 1)

	Mesh = CreateMesh()
	Surface = CreateSurface(Mesh)

	AddVertex(Surface, -1, 0, -1, 0, 0)
	AddVertex(Surface, 1, 0, -1, 1, 0)
	AddVertex(Surface, -1, 0, 1, 0, 1)
	AddVertex(Surface, 1, 0, 1, 1, 1)

	VertexNormal(Surface, 0, 0, 1, 0)
	VertexNormal(Surface, 1, 0, 1, 0)
	VertexNormal(Surface, 2, 0, 1, 0)
	VertexNormal(Surface, 3, 0, 1, 0)

	AddTriangle(Surface, 0, 1, 2)
	AddTriangle(Surface, 1, 3, 2)
	
	If DoubleSided
		AddTriangle(Surface, 0, 2, 1)
		AddTriangle(Surface, 1, 2, 3)
	EndIf

	Return Mesh
	
End Function