DMX

DMX (Data Model eXtensible?) is a binary file format used in newer Valve technologies. It appears to be a generic replacement for ASCII formats like SMD or VDF. Currently it has two known uses: Particle systems (.pcf) and model source data (.dmx).

DMX has several advantages over VDF. It is:

1. Efficient, especially when storing large ints or accurate floats
2. Generic, and able to store most memory structures
3. Robust, since it does not have to worry about delimiters, line breaks or unclosed quote blocks

Using DMX

With DMX being a binary format, it is not practical either to infer how a given file works from reading it, or to alter one by hand. When the tools for reading/writing them aren't publicly available, this is a problem!

Models

DMX model source files are generated by vsdmxio, which only available publicly as a Maya plugin (sourcesdk/maya/2009/plug-ins/valveSource/). Some editing options are available with the Source 2009 SDK tool dmxedit however, including export to OBJ (unweighted, no animations).

To use dmxedit:

• Create an empty file called vs.lua in the SDK binaries folder. This is probably meant to contain commands that are executed every time you run the tool.
• You must then create a LUA file containing the actions you want to perform. Here is a simple example that exports to OBJ:

Load( "<path_to_dmx>" )
Save("<export_path>.obj")

• Perform dmxedit myfile.lua to run the script.

If export a mesh DMX to OBJ you will get a single file. If you export a morph DMX you will get one OBJ for each flex animation that was in the file. If you chose an animation you will get nothing; it seems that dmxedit doesn't support animations.

Programming

#include "cbase.h"
#include "dmxloader/dmxloader.h"
#include "dmxloader/dmxelement.h"

CON_COMMAND(test_dmx, "Loads and interprets a DMX file")
{
	DECLARE_DMX_CONTEXT();
	
	CDmxElement* DMX = (CDmxElement*)DMXAlloc( 50000000 );
	CUtlBuffer buf;

	if (UnserializeDMX(args[1],"MOD",false,&DMX))
	{
		for (int i=0;i<DMX->AttributeCount();i++)
		{
			CDmxAttribute* cur = DMX->GetAttribute(i);
			Msg("%s\t%i\n",cur->GetName(),cur->AttributeDataSize(cur->GetType()));
		}

		SerializeDMX(buf,DMX);
		// write buf to file
	}
	else
		Warning("Could not read DMX file %s\n",args[1]);
}