Lightmapping - texture bleeding ???

Blitz3D Forums/Blitz3D Programming/Lightmapping - texture bleeding ???

cywhale

(Posted 2004) [#1]

Hello.

I´m trying to develope a lightmapping system, mainly for learning purpose, a just-for-fun-project.

But now there is one problem i just cannot solve:

A mesh gets lightmapped, the maps are displayed, the textures seem to fit - but the lightmaps seem to bleed.

I´ve read all i could find (blitzbasic.com-forum, blitzcoder-forum, other graphics-boards,...) about this problem, but none of my wannabe-solutions fixed the problem.

Maybe somebody of the b3d-masters can help me out?

The code to create a lightmap image and setup of texture coords:

Function create_lightmap(meshobj,size#,lmsize#,cset=0)
fnt=LoadFont("arial",10)
SetFont fnt

	
	For sys.lmsystem=Each lmsystem
		tricount=sys\tris
	Next
	
	mapw#=tricount*size
	maph#=size

	x#=0
	y#=0
	
	lm=CreateTexture(lmsize,lmsize,512)
	SetBuffer TextureBuffer(lm) 
	
	For tri.triangle=Each triangle
		DebugLog "Tri: "+t+" X:"+x
		CopyRect(0,0,size,size,x,y,TextureBuffer(tri\lightmap),TextureBuffer(lm))

;**********************************
;right here seems to be the problem
	
	For vert=0 To 2
			u#=((tri\pu[vert] * (size /lmsize) )+(x/lmsize))
			v#=((tri\pv[vert] * (size / lmsize) )+(y/lmsize))
			DebugLog "VERTEX "+tri\vert[vert]+" Texturcoord: "+u*mapw+" "+v*maph+" - "+tri\pu[vert]+" "+tri\pv[vert]
			 VertexTexCoords(tri\surface,tri\vert[vert],u,v,1,cset)

;*********************************
		Next
		;Color 255,255,255
		;Rect x,y,size,size,0 	


		DebugLog ""
		x=x+size
		t=t+1
	Next
	
	SetBuffer BackBuffer()
	
	TextureCoords lm,cset
	TextureBlend(lm,3)
	EntityTexture(meshobj,lm,0,cset)
	
	mapimage=CreateImage(mapw+20,maph+20)
	CopyRect(0,0,mapw+20,maph+20,0,0,TextureBuffer(lm),ImageBuffer(mapimage))
	Return(lm)
End Function

It´s just the code, working (with bleeding), erased my attempts - better to read...

Screenshot:

Any help would really be appreciated.

Cy

Genexi2

(Posted 2004) [#2]

I think the bleeding may have to do with the bilinear filtering...I cant think of many ways around it aside from leaving 1 pixel borders between each lightmapped face...

cywhale

(Posted 2004) [#3]

Little success:

Got rid of the dark edges, but the slightly colored edges remain.
Does ANYBODY have an idea ?????

For vert=0 To 2
			If minu#>tri\pu[vert] Then minu#=tri\pu[vert]
			If maxu#<tri\pu[vert] Then maxu#=tri\pu[vert]
			If minv#>tri\pv[vert] Then minv#=tri\pv[vert]
			If maxv#<tri\pv[vert] Then maxv#=tri\pv[vert]
		Next
		For vert=0 To 2
			If minu#=tri\pu[vert] Then addu#=(1/lmsize)*.5
			If maxu#=tri\pu[vert] Then addu#=-(1/lmsize)*.5
			If minv#=tri\pv[vert] Then addv#=(1/lmsize)*.5
			If maxv#=tri\pv[vert] Then addv#=-(1/lmsize)*.5
			u#=((tri\pu[vert] * (size /lmsize) )+(x/lmsize))+addu#
			v#=((tri\pv[vert] * (size / lmsize) )+(y/lmsize))+addv#
			DebugLog "VERTEX "+tri\vert[vert]+" Texturcoord: "+u*mapw+" "+v*maph+" - "+tri\pu[vert]+" "+tri\pv[vert]
			 VertexTexCoords(tri\surface,tri\vert[vert],u,v,1,cset)
		Next

Changes: Searching vor min/max uv´s of tri, then adding .5 texel for min-u/v, substracting .5 texel of every max-u/v

Cy

sswift

(Posted 2004) [#4]

See if texel can see light source, not if light source can see texel.

cywhale

(Posted 2004) [#5]

Thanks, works now without black borders/bleeding colors (tried chanching direction before, you mentioned it in another old thread, but didn´t work at that time...?)

But - surprise - another problem. Looks like the lightmapping algorithm dosn´t work if i rotate the mesh before lightmapping. Textures get totally distorted, looks like there is an error in the planar mapping code...will post code later, i´m at work right now...

Anybody had a similar problem?