DMX

DMX (Data Model eXchange) stores a Datamodel object, encoded as either binary or ASCII (KeyValues2). The unreleased SDK tool dmxconvert can convert a DMX between them.

The internal structure ("format") of a DMX is defined by the user.

Encodings

KeyValues2

This ASCII encoding is the successor to KeyValues. It's good if you have a small DMX and want it hand-editable.

Tip:When hand-editing, you can generate IDs for new elements with this website (or with guidgen itself, if you have the Windows SDK installed).

Bug:It is not currently possible to serialise a Datamodel to KV2 with the SDK.  [todo tested in ?]

Binary

Compared to KeyValues2, binary DMX is:

1. Small, especially when storing large ints or accurate floats
2. Fast, as values do not have to be converted to or from human-readable characters
3. Robust, since it does not have to worry about delimiters, line breaks or unclosed quote blocks
4. Inscrutable, because it contains native binary data

Binary is good for large DMXes.

Formats

These are the formats used by Valve.

Particle System

Created by the Particle Editor and read by the engine, usually with the extension pcf. There should be no reason to manipulate these yourself.

Model

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

Handling DMX files has many similarities to handling KeyValues. The big architectural differences are that:

• Where KVs had keys, Datamodel has CDmxElement objects containing CDmxAttribute (which can point to further elements).
• There is support for arrays.
• Attribute values are accessed through a single templated function, not lots of different ones.
• Each element has a unique 256-bit ID, which can be used like a pointer to reference any other element loaded into memory.
• There can be multiple roots in each serialised DMX file.

Todo: CDmxElement vs CDmElement

For a full list of attribute types, see the bottom of public\datamodel\dmattributetypes.h.

Note:Strings are CUtlString objects, not char!

Note:The SerializeDMX() overload that includes a file path does not work. You must serialize to a buffer then write out manually.

Creating

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

CON_COMMAND( dmx_create, "Makes a simple DMX" )
{
	DECLARE_DMX_CONTEXT();
	CDmxElement* DMX = CreateDmxElement("MyElementTypeName");

	CDmxAttribute* curAttr = DMX->AddAttribute("Hello");
	curAttr->SetValue("world");

	CUtlBuffer buf;
	SerializeDMX(buf,DMX);

	FileHandle_t fh = filesystem->Open("test.dmx","w","DEFAULT_WRITE_PATH");
	filesystem->Write(buf.Base(),buf.TellPut(),fh);
	filesystem->Close(fh);
}

Iterator

This code will print string, int, float and bool values in the given DMX to the console.

Todo: Elegant solution to arrays.

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

void IterateDmxElement(CDmxElement* pRoot)
{
	for (int i=0;i<pRoot->AttributeCount();i++)
	{
		CDmxAttribute* pCur = pRoot->GetAttribute(i);
		CDmxElement* subElem;
		
		Warning( "%s: ",pCur->GetName() );

		switch (pCur->GetType())
		{
		case AT_ELEMENT:
			subElem = pCur->GetValue<CDmxElement*>();
			if (subElem)
				IterateDmxElement(subElem);
			break;

		case AT_STRING:
			Msg( "STRING | %s\n",pCur->GetValue<CUtlString>().Get() );
			break;
		case AT_INT:
			Msg( "INT | %i\n",pCur->GetValue<int>() );
			break;
		case AT_FLOAT:
			Msg( "FLOAT | %f\n",pCur->GetValue<float>() );
			break;
		case AT_BOOL:
			Msg( "BOOL | %s\n",pCur->GetValue<bool>() ? "true" : "false" );
			break;
		
		default:
			Msg("Unknown type %i\n",pCur->GetType());
			break;
		}
	}
}

CON_COMMAND(dmx_iterate, "Prints a DMX file to the console")
{
	DECLARE_DMX_CONTEXT();
	
	CDmxElement* DMX = (CDmxElement*)DMXAlloc( 50000000 );

	if (UnserializeDMX(args[1],"MOD",false,&DMX))
	{
		IterateDmxElement(DMX);
	}
	else
		Warning("Could not read DMX file %s\n",args[1]);
}