PHY

PHY is the extension for Source's proprietary collision model data format. It stores data for the rigid or jointed (ragdoll) collision model used by the MDL. In addition, it stores some $keyvalues about a model such as which gib-models to use if destroyed.

File Format

In brief, a PHY file is formed by:

• A main header, which specifies the number of solids
• A series of VPHY/collision data sections, one per solid
• A single text data section, variously-ordered block elements that specify which solid they apply to

Main header

The first bytes of the file form the main header:

// this structure can be found in <mod folder>/src/public/phyfile.h
struct phyheader_t
{
	int		size;           // Size of this header section (generally 16)
	int		id;             // Often zero, unknown purpose.
	int		solidCount;     // Number of solids in file
	long	        checkSum;	// checksum of source .mdl file (4-bytes)
}

Collision data sections

There will be a series of these sections, back-to-back, numbering the same as the header's solidCount.

{
	int		size;           // Size of the content after this byte
	int		id; 		// Generally the ASCII for "VPHY" in newer files
        //TODO fill in remaining data
}

Todo: Document details of each collision section

Todo: Document "old format" if VPHY is not seen

Text section

The text section occurs near the end of the file, and is one single string with no size header. Among the text blocks it may contain:

• solid blocks define solids, using an index value to distinguish which set of collision data they refer to.
• ragdollconstraint blocks define relationships between parent and child solids.
• An editparams block with general information about the entire object.
• Various break blocks with information about rigid or jointed gibs created when the model is destroyed.

Here is an incomplete sample from the Combine Strider, formatted for readability.

solid {
	"index" "8"
	"name" "Combine_Strider.Leg_Hind_Bone1"
	"parent" "Combine_Strider.Leg_Hind_Bone"
	"mass" "137.739014"
	"surfaceprop" "strider"
	"damping" "0.000000"
	"rotdamping" "1.000000"
	"inertia" "1.000000"
	"volume" "109397.476563"
} 
ragdollconstraint {
	"parent" "7"
	"child" "8"
	"xmin" "0.000000"
	"xmax" "0.000000"
	"xfriction" "2.000000"
	"ymin" "0.000000"
	"ymax" "0.000000"
	"yfriction" "2.000000"
	"zmin" "-32.000000"
	"zmax" "138.000000"
	"zfriction" "0.200000"
}
editparams {
	"rootname" "combine_strider.body_bone"
	"totalmass" "2000.000000"
} 
break {
	"model" "Gibs/Strider_Gib1" 
	"health" "0" 
	"fadetime" "0" 
	"placementbone" "Combine_strider.body_bone"
}
break {
	"ragdoll" "Gibs/Strider_Head" 
	"health" "0" 
	"fadetime" "0"  
}

See also

• Model Creation Overview