Making a custom breakable surface

==What you need==
You will need:
*A VTF editor/maker (VTFEdit was used in the making of this tutorial, but VTEX can be used also.) to manipulate the textures as .VTF files
*A VTF texture to represent the intact material
*A VTF texture with an alpha channel (8-bit alpha for semi-transparent surfaces) to represent the damaged material
A mask for both textures is optional.
==Handling the material/texture files==
*After you've got your 2 masks and/or textures, place them in the appropriate game/mod materials directory (and whatever subfolders you wish to put them in) (e.g Half-Life 2/hl2/materials). 
*Create 2 text documents in the same folder your VTFs are in, with each one sharing a file name with one of your VTF texture files respectively. Make sure you have extensions visible in your computer's file browser, then change the file extension of one text file to .vmt, or save a text document with a .vmt file extension in whatever text editor you're using.
:
==The intact texture==
After you have created the material/textures in the appropriate paths, copy, paste and fill the "(...)" enclosed strings with the paths to the respective VTF files into your intact material VMT:
"LightmappedGeneric"
{
	"$basetexture" "(VTF NAME HERE)"
	"$envmap" "env_cubemap"
	"$surfaceprop" "(Surface property param goes here, is usually glass)"
	"$envmapmask" "(VTF MASK NAME GOES HERE (if used that is, otherwise comment out this line with //))" 
	"$translucent" 1
	"$multipass" 1
	"$nocull" 1
	"$crackmaterial" "(DAMAGED MATERIAL PATH GOES HERE)"
	"LightmappedGeneric_hdr_dx9"
	{
		"$envmaptint" "[.08 .08 .08]" 
	}
}
Insert the appropriate paths where $basetexture, $envmapmask and $crackmaterial are specified
Save the VMT in the same folder as your first (intact) VTF file
==The damaged texture==
The damaged texture needs to have an alpha channel otherwise skybox/black texture will appear when the surface breaks.
Copy and paste the following code into your damaged material VMT
"ShatteredGlass"
{
	$basetexture "(VTF NAME GOES HERE)"
	$detail "(VTF NAME GOES HERE)"
	$envmap "env_cubemap"
	$surfaceprop "(Surface properties goes here, it's glass by default)"
	$envmapmask "(TEXTURE MASK GOES HERE (if used, otherwise comment out this line with //))"
	$translucent 1
	$basetexturetransform "scale .7 .7"
	$detailscale 0.7
	$unlitfactor 0.0
	"ShatteredGlass_DX8"
	{
		$unlitfactor 0.3
		// This is roughly equal to the average value of envmapmask of the unbroken texture
		$envmaptint "{201 201 201}"
	}
	// On the low end, envmaptint + lightmap tint both use the average alpha value 
	"ShatteredGlass_DX7"
	{
		// This is roughly equal to the average value of alpha channel of the unbroken basetexture
		$lightmaptint "{128 128 128}"
		// This is roughly equal to the average value of envmapmask of the unbroken texture
		// times the average value of the alpha value of the unbroken base texture
		$envmaptint "{100 100 100}"
	}
	$nocull 1
	%notooltexture 1 // hide in texture browser, because it isn't intended to be used directly
	"Proxies"
	{
		"BreakableSurface"
		{
		}
	}
}
==End==
Provided you have done everything right, you should now have a texture that works fully with the func_breakable_surf brush entity provided all except 1 side is Nodraw.
Modifications to the other parameters (e.g $lightmaptint) can of course be made without any loss of functionality.
==See also==
*Breakable Glass
*func_breakable_surf
Category:Material System
Category:Tutorials