Introduction

This document describes how to create, interpret, and modify Infini-D 3.0-3.5 scene files and object library files. A scene file describes either a static 3D scene or a 3D animation, and includes parameters for geometric objects, lights, cameras, surfaces, effects, and time-based transformation parameters. An object library file describes the geometry of a single SplineForm&tm; object, which describes a path, 4 rails, and 1 or more cross-sections to form a cubic Bezier-patch surface.

About the Elmo Block Structure.

Infini-D versions 3.0 and later use the Elmo file format. Elmo is a nested block structure which brings order to an otherwise chaotic collection of data. Elmo's main features are:

a) Each file is a list of 1 or more blocks.

b) Each block has a list of 0 or more subblocks after the main block data.

c) Each block has a header containing the block type, a unique block ID (the Tag), the block size, and the position of the first subblock.

d) Blocks have a fixed or variable size depending on the block type.

e) Any block can have extra data added by adding a subblock of a new type.

f) Any unrecognised block types are ignored, to allow backward compatibility.

g) Blocks are written in a standard order for efficiency of reading.

h) File readers can take advantage of the expected order for efficiency, but should not expect blocks in a particular order to allow for new and unrecognised block types.

i) Integers and other values are ordered with the most-significant byte first (big-endian), as is typical with Macintosh data.

A Single Elmo Block

Block Type Summary - In order of occurrence

Block Type Summary - Alphabetical

Scene file structure.

elmo	-------file header
	scen	-------one scene block
	csrf	-------one block per composite surface, in a mixed list of basic and composite surfaces.
		csla	-------one block per composite surface layer
	surf	-------one block per basic surface, in a mixed list of basic and composite surfaces. Basic surfaces have 1 or 2 surface mapping subblocks: -------one image mapping subblock from list below.
		rgb	-------RGB color parameter.
		tile	-------tiling parameters.
		frct	-------fractal parameters.
		nois	-------noise parameters.
		marb	-------marble parameters.
		wood	-------(old style) wood parameters.
		natw	-------natural wood parameters.
		imag	-------image map parameters.
			alis	-------one file alias block.
			qtsp	-------one QuickTime surface parameter block.
		-------optionally one bump mapping subblock from list below.
		nois	-------noise parameters.
		wave	-------wave parameters.
	lite	-------one per light
		lnsf	-------one lens flare block per light.
	obj	-------one per object, including cameras and lights, in a tree structure.
		obx1	-------one object extended block per object.
		terr	-------one terrain block for terrain objects
			frct	-------one fractal data block for fractal terrains.
			imag	-------one image block for image mapped terrains.
				alis	-------one file alias block
		modl	-------one model block for polygonal mesh objects.
			verl	-------one vertex list.
			edgl	-------one edge list.
			facl	-------one face list.
				indl	-------multiple edge or neighbour index lists blocks.
		evtm	-------one for each event mark of object. Event marks have different sets of parameters stored with the subblocks below:
			afev	-------affine event data.
			raev	-------rotation Affine event data.
			caev	-------camera event data.
			liev	-------light event data.
				lfev	-------one lens flare event data. block.
			sfev	-------surface event data.
			ppev	-------path-profile event data.
				pmdl	-------one path model data block.
					ppro	-------one path-profile data block.
						ol3d	-------5 outline 3D data blocks (path & 4 rails).
						pf2d	-------one profile2D block for each cross-section.
							ol2d	-------one outline2D block for each curve in a cross-section.
			ptev	-------path-profile text event data.
				pmdl	-------one path model data block (see above for subblocks)
			trev	-------terrain event data.
				frct	-------Fractal parameters.
	envv	-------one environment variables block.
	seqv	-------one sequence variables block.
	bkmk	-------one per bookmark, forming a linked list of blocks.
	view	-------one per view, forming a linked list of blocks.
		vwx2	-------one view extended block per view.
	outl	-------one per outline object, forming a link list of blocks.
		pypt	-------5 polypoint lists per outline object.
			pylp	-------one or more Polypoint Loop blocks per Polypoint block.
	sqin	-------one sequencer info block.
		sqob	-------one per object listed in sequencer.
	sprf	-------one scene preferences block.
	end!	-------one EOF block.

Object Library file structure

Version History

Infini-D version 3.0.1 was released shortly after 3.0. This bug-fix release did not have any file format changes.

Infini-D version 3.1 was released in October 1995. The QuickTime -Surface-Parameters block (`qtsp') was introduced, and the ElmoIndexUnion type was modified to correct smoothing problems with polygonal mesh models having 65,535 or more faces.

Infini-D version 3.2 was released in April 1996. This version did not have any file format changes.

Infini-D version 3.5 was released in August 1996. New block types were Lens-Flare (`lnsf'), Lens-Flare-Event (`lfev'), Object-Extended (`obx1'), View-Extended (`vwx2'), Scene-Preferences (`sprf').

Please note that all elmo scene files are backward compatible to Infini-D version 3.0, since unrecognised block types are ignored. See "About the Elmo Block Structure" for more information.

Data Types.

General Types
Name	Bytes	Description
ElmoUInt8	1	8 bit unsigned integer
ElmoUInt16	2	16 bit unsigned integer
ElmoUInt32	4	32 bit unsigned integer
ElmoInt8	1	8 bit signed integer
ElmoInt16	2	16 bit signed integer
ElmoInt32	4	32 bit signed integer
ElmoFloat32	4	32 bit floating point number (IEEE single precision)
ElmoBoolean	1	8 bit boolean value. 1 = TRUE, 0 = FALSE.
ElmoPString	varies	A Macintosh "Pascal" string, where the first byte is the number of characters (0-255) in the string that follows. There is no terminating character. Note that the maximum string length is one less than the number of bytes available.
Block header types
Name	Bytes	Description
ElmoType	4	4-character code, e.g. 'elmo'. Characters must be in the range 32-216 ($20-$D8).
ElmoTag	4	An identifying number unique to each block in an elmo file. A 32 bit unsigned value.
			Reserved block numbers are:
			kNotAnElmoTag = 0	No block or end of block list.
			kElmoEOFTag = -1	Tag of "end!" block.
			Elmo file header = 1	Tag of file header block.
ElmoBlockHeader	16	The standard header for each Elmo block:
		4	ElmoType	a 4-character code which determines the block contents, e.g. "scen" for scene files. Characters must be in the range 32-2216 ($20-$D8).
		4	ElmoTag	unique identifying number for each block in a file.
		4	ElmoUInt32	block size in bytes, including header and subblocks.
		4	ElmoUInt32	subblock offset: the number of bytes from the start of the block to the first subblock. If there are no subblocks then the offset equals the block size.
Geometric types
Name	Bytes	Description
ElmoPoint2D	8	A 2D point (ElmoFloat32: x, y)
ElmoIntPoint2D	4	A 2D Macintosh-style point (ElmoInt16: x, y)
ElmoPointST	8	A point for texture mapping (ElmoFloat32: s, t)
ElmoPoint3D	12	a 3D point or 3D vector (x, y, z)
ElmoPoint4D	16	a 4D point or 4D vector (x, y, z, w)
ElmoQuaternion	16	a quaternion (a useful way to represent rotation: c, x, y, z)
ElmoRect	16	a rectangle (left, top, right, bottom)
ElmoIntRect	8	an integer, Macintosh-style rect (top, left, bottom, right)

Color types
Name	Bytes	Description
ElmoRGBInt8Color	4	A Macintosh-style RGB color
		1	ElmoUInt8	red
		1	ElmoUInt8	green
		1	ElmoUInt8	blue
		1	ElmoUInt8	padding (reserved, set to 0)
ElmoRGBIntColor	6	A Macintosh-style RGB color
		2	ElmoUInt16	red
		2	ElmoUInt16	green
		2	ElmoUInt16	blue
ElmoRGBColor	12	an RGB color (each component ranges from 0.0--1.0)
		4	ElmoFloat32	red
		4	ElmoFloat32	green
		4	ElmoFloat32	blue
ElmoHSVColor	12	an HSV color (each component ranges from 0.0--1.0)
		4	ElmoFloat32	hue
		4	ElmoFloat32	saturation
		4	ElmoFloat32	value
ElmoColorTransition	28	an RGB or HSV transition from one color to another
		2	ElmoUInt16	padding (reserved, set to 0)
		2	ElmoUInt16	transition type (ElmoRGBTransition = 0, ElmoHSVTransition = 1)
		12	ElmoRGBColor / ElmoHSVColor	start
		12	ElmoRGBColor / ElmoHSVColor	end
ElmoAlphaMode	1	What kind of alpha channel for an image?
			kElmoNoAlpha = 0
			kElmoStraightAlpha = 1
			kElmoMultipliedAlpha = 2
Object transform types
Name	Bytes	Description
ElmoAffine	72	An object's affine data.
		12	ElmoVector3D	scale	local scale; does not affect children
		12	ElmoVector3D	offset	local offset; does not affect children
		12	ElmoVector3D	tree_scale	"uniform scale"; passed down to children
		12	ElmoVector3D	rotation	passed down to children
		12	ElmoVector3D	shear	passed down to children
		12	ElmoVector3D	position	passed down to children
ElmoConstraint3D	28	An object's constraint information (rotation, scale, or position).
		12	ElmoVector3D	min
		12	ElmoVector3D	max
		1	ElmoBoolean	xLocked
		1	ElmoBoolean	yLocked
		1	ElmoBoolean	zLocked
		1	ElmoBoolean	reserved

Bezier spline types
Name	Bytes	Description
PtNode2D_Elmo_Struct	28	A point node on a 2D cubic Bezier spline.
		2	ElmoUInt16	reserved
		1	ElmoUInt8	reserved
		1	ElmoUInt8	kind	kPlainKind=0
					kCornerKind=1
					kCurveKind=2
					kSmoothKind=3
		8	ElmoPoint2D	position
		8	ElmoPoint2D	LControl
		8	ElmoPoint2D	RControl
PtNode3D_Elmo_Struct	40	A point node on a 3D cubic Bezier spline.
		2	ElmoUInt16	reserved
		1	ElmoUInt8	reserved
		1	ElmoUInt8	kind	kPlainKind=0
					kCornerKind=1
					kCurveKind=2
					kSmoothKind=3
		12	ElmoPoint3D	position
		12	ElmoPoint3D	LControl
		12	ElmoPoint3D	RControl
Polygonal Model types
Name	Bytes	Description
ElmoModelIndex	4	An index into a Polygonal model's face, edge, or vertex list (an unsigned integer)
ElmoEdge	8	An edge of a polygonal mesh model.
		4	ElmoModelIndex	index1	Index into vertex list; vertex has coordinates of 1st endpoint.
		4	ElmoModelIndex	index2	Index into vertex list; vertex has coordinates of 2nd endpoint.
ElmoFace	40	A "face", a 3 or more sided 3D polygon; a facet of a polygonal mesh model.
		4	ElmoUInt16	flags	kElmoFlatFace = 0 (face is planar)
					kElmoInterpFace = 1 (face not planar)
		4	ElmoModelIndex	edgeCount	Number of edges
		16	ElmoIndexUnion	edgeList	4 edge indexes or Tag of (edge) index list, in CCW order.
		16	ElmoIndexUnion	neighborList	4 neighbouring face indexes or Tag of (neighbouring face) index list, in CCW order and corresponding to the above edgeList.
ElmoIndexUnion	16	A list of up to 4 indices *OR* the tag of a subblock with a list of 5 or more indices. Used for a face's edge and neighbour lists - since most faces have 3 or 4 edges and 3 or 4 neighbours, we optimize for that case. Edges and Faces must be listed in counter-clockwise order (CCW from the outside perspective). If a face does not exist, or smoothing towards the neighbouring face is not desired, the constant K_no_neighbouring_face is used. K_no_neighbouring_face is 0xFFFFFFFF for version 3.1 or later, 0xFFFF for version 3.0 or 3.0.1.
		(if ElmoFace.edgeCount is 4 or less)
		4	ElmoModelIndex	index[0]	Index of the first edge or neighbour
		4	ElmoModelIndex	index[1]	Index of the second edge or neighbour
		4	ElmoModelIndex	index[2]	Index of the third edge or neighbour
		4	ElmoModelIndex	index[3]	Index of the fourth edge or neighbour
		(or, if ElmoFace.edgeCount is 5 or more)
		4	ElmoTag	indexListTag	Tag of Index List subblock (holds edge list or face list).
Outline Model types
Name	Bytes	Description
Elmo_Polypoint_Node	8	A node of a polypoint loop
		4	ElmoPoint2D	pt
		2	ElmoUInt16	padding
		2	ElmoInt16	mode	K_straight_segment = 0
					K_interpolated_segment = 1
					K_bezier_segment = 2 (cubic spline)
					K_bezier_2_segment = 3 (quadratic spline)

Block Reference.