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?how to SaveB3D Lightmapping Data

Blitz3D Forums/Blitz3D Programming/?how to SaveB3D Lightmapping Data

Duckstab[o](Posted 2005) [#1]
Ive Been making my own meshes for a tileset engine and want the ability to Export and lightmap if the user wishes

So I use Jfk's SaveB3d Function To Export a multi surface Mesh

Then LightMap This in SlimShady

But I cant configure SaveB3d Function to Load in the Lightmap data

For a Combined mesh Export

Anybody got some code snippets showing multitex SaveB3d

any Help welcome Thanks

btw jfk cool tools :)


jfk EO-11110(Posted 2005) [#2]
Thanks. Well, SaveB3D doesn't LOAD anything, it will only save a Mesh.

If you want to load a lightmapped Mesh and then save it with the SaveB3D Function, you first need to track down the Lightmap Texture as well. THis may be pretty easy, use the command GetBrushTexture with the second, optinal INDEX parameter.
I think this would be:
lightmaptex=GetBrushTexture(brush,1) ; use 0 or 1, 1 for LIghtmap, AFAIK
lima_texfile$=texturename$(lightmaptex)

Now that you know the texture file that is used for the lightmap as a second texture layer on each brush, you can modify the SaveB3D Function easily, have a look at the comments, and these lines:
b3dBeginChunk( "TEXS" ) ; list all textures used by the mesh
For i=1 To c_surfs
 b3dWriteString( c_tex_name$(i) ) ;texture file
 b3dWriteInt( 1 );flags
 b3dWriteInt( 2 );blend
 b3dWriteFloat( 0 );x in tex 0 (hu?)
 b3dWriteFloat( 0 );y in tex 0
 b3dWriteFloat( 1 );x scale 1
 b3dWriteFloat( 1 );y scale 1
 b3dWriteFloat( 0 );rotation 0
Next

You see, in the TEX chunk all textures are inserted. Basicly the TEX chunk lists all teyxtures that may be used by the mesh. The Function assumes that each surface has exactly one texture, so it only counts up to the number of surfaces and inserts the surface-brushes texture info for each surface.
You may add an additional texture info block for the Lightmap. You may do this as the first block, or as the last block (pre or past the For loop), but it must be inside the TEX chunk. Something like:
 b3dWriteString( lima_file$ ) ;texture file
 b3dWriteInt( 1 );flags
 b3dWriteInt( 2 );blend - uh right now I don't remember exactly what blendmode needs to be used, but probably you have to try some modes
 b3dWriteFloat( 0 );x in tex 0
 b3dWriteFloat( 0 );y in tex 0
 b3dWriteFloat( 1 );x scale 1
 b3dWriteFloat( 1 );y scale 1
 b3dWriteFloat( 0 );rotation 0

(please note: use the right blend mode, "addition" or something)

Now heres a number of BRUS chunk, each one defines a Brush. Some people use only one BRUS chunk and include all Bsushes inside, but they need to use the same number of Texture Layers for each Brush, even when Layers can be deactivated by using -1 as index, if I remember right. However, this Function uses a method that defines a BRUS chunk for each Brush, this way each Brush can have its individual number of Textures. If you have added the lightmap info block in the TEX chunk after the For loop, you could do it this way:
For i=1 To c_surfs
 b3dBeginChunk( "BRUS" ) ; describe all brushes used by the mesh
 b3dWriteInt( 2 );number of textures per brush
 b3dWriteString( "brush"+(i-1) );brushname
 b3dWriteFloat( 1 );red
 b3dWriteFloat( 1 );green
 b3dWriteFloat( 1 );blue
 b3dWriteFloat( 1 );alpha
 b3dWriteFloat( 0 );shininess
 b3dWriteInt( 1 );blendmode
 b3dWriteInt( 1 );FX >>> lightmapped meshes usually are FX 1
 b3dWriteInt( i-1 );used "material" texture index
 b3dWriteInt( c_surfs ); index of the lightmap

b3dEndChunk();end of BRUS chunk
Next


Now the mesh still needs to know what to do with the lightmap, so you need to save the second UV Coords, in the Function it's already there, only remarked, so you only have to activate these two lines in the function WriteMESH( mesh ):

;;b3dWriteFloat( VertexU#( surf,j,1 ) ) ; lightmap uv
;;b3dWriteFloat( VertexV#( surf,j,1 ) ) ; lightmap uv

plus chanche this line:
b3dWriteInt( 1 );number of tex_coord sets
to
b3dWriteInt( 2 );number of tex_coord sets

Now you should be pretty close to a working Mesh exporter that works with lightmaps- Additionally you learned something about the format.


Duckstab[o](Posted 2005) [#3]
Thanks jfk think ive got to grips with it now


Duckstab[o](Posted 2005) [#4]
Jfk Got that sorted But the Lightmap Texture is Being Placed on the same Uv as the Normal Texture is there Another Texture Detail that must be added for the lightmap texture

Thanks for your help


Duckstab[o](Posted 2005) [#5]
Just Hacked the mesh and checked Its deffo the Problem of it being asigned to the default Texturecoords

Added Small Code after loading
and the lightmap appeared correctly