3D Theory - XML Schema

Prerequisites

This page suggests a possible way to store the physics information using XML. If you are not familiar with XML you may like to look at the following pages first:

The fields used in this schema are described in detail here:

modelling physics using scenegraph

Schema

Here is a draft XML schema for storing a simulation of solid bodies using Newtonian mechanics.

Physics Schema

This schema is intended to be used with the x3d schema but I have not yet separated the out the namespaces correctly.

There is a lot more work that needs to be done and a lot of fundamental issues to be resolved, for instance:

x3d allows the external shape of objects to be defined, this is fine for collision detection and rendering, but its not so good if we need to define the internal structure of an object.
x3d uses 3d vectors to represent location and axis-angle to represent orientation. I'm not sure this is very appropriate for physics calculations. I would like to investigate the use of multivectors as described here.

Listing

<?xml version="1.0" encoding="utf-8" ?>
<xs:schema targetNamespace="http://tempuri.org/XMLSchema.xsd" elementFormDefault="qualified" xmlns="http://tempuri.org/XMLSchema.xsd" xmlns:mstns="http://tempuri.org/XMLSchema.xsd" xmlns:xs="http://www.w3.org/2001/XMLSchema" id="physicsSim">
<xs:element name="kinematics">
<xs:annotation>
<xs:appinfo />
<xs:documentation source="http://www.euclideanspace.com/threed/animation/datastructure/usescenegraph/index.htm" />
</xs:annotation>
<xs:complexType>
<xs:sequence>
<xs:element name="position" type="SFVec3f" />
<xs:element name="velocity" type="SFVec3f" />
<xs:element name="acceleration" type="SFVec3f" />
<xs:element name="angularPosition" type="SFRotation" />
<xs:element name="angularVelocity" type="SFRotation" />
<xs:element name="angularAcceleration" type="SFRotation" />
<xs:element name="randomMinMax" type="SFVec2f" />
<xs:element name="initPosition" type="SFVec3f" />
<xs:element name="initVelocity" type="SFVec3f" />
<xs:element name="initAcceleration" type="SFVec3f" />
<xs:element name="initAngularPosition" type="SFRotation" />
<xs:element name="initAngularVelocity" type="SFRotation" />
<xs:element name="initAngularAcceleration" type="SFRotation" />
<xs:element name="enable" type="SFBool" />
<xs:element name="rewind" type="SFBool" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="Dynamics">
<xs:annotation>
<xs:appinfo />
<xs:documentation source="http://www.euclideanspace.com/threed/animation/datastructure/usescenegraph/index.htm" />
</xs:annotation>
<xs:complexType>
<xs:sequence>
<xs:element name="collideWith" type="Transform" />
<xs:element name="mass" type="xs:double" />
<xs:element name="centreOfMass" type="SFVec3f" />
<xs:element name="inertiaMatrix" type="xs:string" />
<xs:element name="gravity" type="xs:double" />
<xs:element name="material" type="xs:string" />
<xs:element name="solid" type="SFVec3f" />
<xs:element name="friction" type="SFVec3f" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="constraints">
<xs:annotation>
<xs:appinfo />
<xs:documentation source="http://www.euclideanspace.com/threed/animation/datastructure/usescenegraph/index.htm" />
</xs:annotation>
<xs:complexType>
<xs:sequence>
<xs:element name="constrainTranslation" type="xs:string" />
<xs:element name="minTranslation" type="SFVec3f" />
<xs:element name="maxTranslation" type="SFVec3f" />
<xs:element name="constrainRotation" type="xs:string" />
<xs:element name="minRotation" type="SFRotation" />
<xs:element name="maxRotation" type="SFRotation" />
<xs:element name="chain" type="xs:string" />
<xs:element name="action" type="xs:string" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="collisionDetect">
<xs:annotation>
<xs:appinfo />
<xs:documentation source="http://www.euclideanspace.com/threed/animation/datastructure/usescenegraph/index.htm" />
</xs:annotation>
<xs:complexType>
<xs:sequence>
<xs:element name="overlap" type="SFBool" />
<xs:element name="flag" type="SFBool" />
<xs:element name="clearFlag" type="SFBool" />
<xs:element name="other" type="Transform" />
<xs:element name="useGeometry" type="SFBool" />
<xs:element name="impactLocation" type="SFVec3f" />
<xs:element name="impactTime" type="xs:time" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="CollisionAction">
<xs:annotation>
<xs:appinfo />
<xs:documentation source="http://www.euclideanspace.com/threed/animation/datastructure/usescenegraph/index.htm" />
</xs:annotation>
<xs:complexType>
<xs:sequence>
<xs:element name="collideWith" type="xs:string" />
<xs:element name="actionThis" type="xs:string" />
<xs:element name="actionOther" type="xs:string" />
<xs:element name="CreateNew" type="xs:string" />
<xs:element name="CreateNumber" type="xs:int" />
<xs:element name="CreateAt" type="xs:string" />
<xs:element name="Counter" type="xs:int" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="Multiple">
<xs:annotation>
<xs:appinfo />
<xs:documentation source="http://www.euclideanspace.com/threed/animation/datastructure/usescenegraph/index.htm" />
</xs:annotation>
<xs:complexType>
<xs:sequence>
<xs:element name="type" type="xs:string" />
<xs:element name="initialInstances" type="xs:int" />
<xs:element name="maximumInstances" type="SFVec3f" />
<xs:element name="addInstance" type="xs:string" />
<xs:element name="removeInstance" type="xs:string" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="Transform">
<xs:annotation>
<xs:appinfo />
<xs:documentation source="http://www.web3D.org/technicalinfo/specifications/vrml97/part1/nodesRef.html#Transform" />
</xs:annotation>
<xs:complexType mixed="false">
<xs:complexContent mixed="false">
<xs:extension base="X3DGroupingNode">
<xs:attribute name="center" type="SFVec3f" default="0 0 0" />
<xs:attribute name="rotation" type="SFRotation" default="0 0 1 0" />
<xs:attribute name="scale" type="SFVec3f" default="1 1 1" />
<xs:attribute name="scaleOrientation" type="SFRotation" default="0 0 1 0" />
<xs:attribute name="translation" type="SFVec3f" default="0 0 0" />
</xs:extension>
</xs:complexContent>
</xs:complexType>
</xs:element>
<xs:element name="SFVec3f">
<xs:complexType>
<xs:sequence>
<xs:element name="x" type="xs:double" />
<xs:element name="y" type="xs:double" />
<xs:element name="z" type="xs:double" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="SFRotation">
<xs:complexType>
<xs:sequence>
<xs:element name="w" type="xs:double" />
<xs:element name="x" type="xs:double" />
<xs:element name="y" type="xs:double" />
<xs:element name="z" type="xs:double" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="SFVec2f">
<xs:complexType>
<xs:sequence>
<xs:element name="x" type="xs:double" />
<xs:element name="y" type="xs:double" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="SFBool">
<xs:complexType>
<xs:sequence>
<xs:element name="value" type="xs:boolean" />
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>

metadata block

see also:	Using this for games generation Tutorial for building a game Tutorial for running a game
Correspondence about this page
Book Shop - Further reading. Where I can, I have put links to Amazon for books that are relevant to the subject, click on the appropriate country flag to get more details of the book or to buy it from them.	If you are interested in 3D games, this looks like a good book to have on the shelf. If, like me, you want to have know the theory and how it is derived then there is a lot for you here. Including - Graphics pipeline, scenegraph, picking, collision detection, bezier curves, surfaces, key frame animation, level of detail, terrain, quadtrees & octtrees, special effects, numerical methods. Includes CDROM with code.
Commercial Software Shop Where I can, I have put links to Amazon for commercial software, not directly related to this site, but related to the subject being discussed, click on the appropriate country flag to get more details of the software or to buy it from them.
Can this page be improved? Please send me any improvements to here. I would appreciate ideas to make the pages more useful including error correction, ideas for new pages, improvements to wording. It helps if you quote the full URL of the page.
progam I am working on a project which uses these principles, if you would like to help me with this you are welcome to join in, here:	http://sourceforge.net/projects/mjbworld/

This site may have errors. Don't use for critical systems.