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name: ISTG.DOC FORM ISTG --------- Unofficial Imagine Staging File Format Rev 1.1 20-08-97 G. Scibilia This is the Unofficial Staging File Format document for the Imagine raytracer (Copyright Impulse Inc., Mpls, MN 55444). This document is sent every so often to answer general questions that users of the 3D rendering software, Imagine by Impulse Inc. may have. It is aimed toward all users, especially coders of third party add-ons or for users who have created their own real time renderer. If you find any errors or have answers to other frequently asked questions that you would like to have included in this document, please send e-mail to: minix@arsenio.disi.unige.it (The Gant at ArtNouveaU) or, via Fidonet, to: 2:332/211.24 (Gabriele Scibilia) - Gabriele Scibilia <G>SZ ~ ArtNouveaU Imagine Mailing List, IML FAQer ======================================================================== First Version : March 6, 1995 Last Update : August 20, 1997 Revision Number : 1.1 CONTENTS: ======== SECTION 1 - Scope of this document SECTION 2 - General informations SECTION 3 - Data types SECTION 4 - ISTG sub-chunks SECTION 5 - SOBJ sub-sub-chunks SECTION 6 - PC (80x86 CPU) notes SECTION 7 - IFF file format notes CLOSING - Closing statements and Disclaimer ======================================================================== SECTION 1 - Scope of this document ======================================================================== This text will describe Imagine's staging file format. It is beyond the scope of this text to describe any of the file formats used for basic object, spline objects, deform tool, or any other object types not mentioned below. However, some of the data described below may apply to some of these undocumented object formats. It is also not the intent of this document to explain the implementation of the information contained in the ISTG files (ie. what equations Impulse programmers use to represent Imagine's paths - lighting models - forms geometry - tweening algorithms, etc.). ======================================================================== SECTION 2 - General informations ======================================================================== FORM ISTG is used by Impulse's Imagine for keyframe animation system data. ISTG stands for "Imagine staging". The files contain keyframe actors definitions, and can be extended to describe different types of actor information. The ISTG file is stored in Amiga (680x0) format, and conforms to the "IFF" file format on that computer. On IBM (80x86) based machines, much of the data refered to below will have to be byte reversed before it makes sense. The IFF (interchange file format) format stores data in packets called "chunks." Each chunk begins with a long word identifier <ID> in ascii format. This identifier is immediately followed by a long word data-size. The data-size is measured in bytes and descrbes how much data, following the data-size long word, is part of the chunk identified by the <ID>. Imagine's IFF structure supports nesting of these chunks. For more info on the IFF standard, see the "Amiga ROM Kernal Reference Manual: Devices (3rd Edition)." Currently, in "standard IFF" terms, a FORM ISTG has only three supported chunk types: a MAXF chunk, a LOOP chunk and a SOBJ chunk describing a staging object data. The FORM has one (obligatory) MAXF chunk followed by one (obligatory) LOOP chunk followed by some number of SOBJ chunks. The SOBJ chunk, in turn, is made up of smaller chunks with the standard IFF structure: <ID> <data-size> <data>. The MAXF and LOOP "sub-chunks" are relatively straightforward to interpret. The SOBJ "sub-chunks" support staging objects and are slightly more difficult to interpret. Currently, there are many types of supported SOBJ sub-chunks. In Imagine, the structure of the staging object is written in a SOBJ chunk as follows: 1) A NAME chunk is written, naming the object. 2) A STGF chunk and a LYR0 is written, marking the start of the object description. 3) Each LYR0 chunk is followed by one or more (or no one) CAMR (camera actor) or GLB? (globals) or FIL? (object actor) or LIT? (light source actor) or AXIS (track axis actor) chunks, describing the object type. 4) Follow these chunks some number of position chunks, alignment, size, association and special effects ones (depending on the choice made when the Specify Type requester was called). Reader software WILL FOLLOW the standard IFF procedure of skipping over any un-recognized chunks -- and "sub-chunks" or "sub-sub-chunks". The <data-size> field indicates how many bytes to skip. In addition it WILL OBSERVE the IFF rule that an odd <data-size> may appear, in which case the corredponding <data> field will be padded at the end with one extra byte to give it an even size. ======================================================================== SECTION 3 - Data types ======================================================================== Now, on with the details (from an official Impulse text that describe FORM TDDD, used by Impulse's Turbo Silver for 3D rendering data and by Imagine for basic object file format). First, there are several numerical fields appearing in the data, describing actor positions, rotation angles, scaling factors, etc. They are stored as "32-bit fractional" numbers, such that the true number is the 32-bit number divided by 65536. So as an example, the number 3.14159 is stored as (hexadecimal) 0x0003243F (ie. 0x0003243F / 65536 = 3.14159). This allows the data to be independant of any particular floating point format. Numbers stored in this format are typedef'ed as "FRACT"s below. Second, there are several color (or RGB) fields in the data. They are always stored as three UBYTEs representing the red, green and blue components of the color. Red is always first, followed by green, and then blue. The three basic data types that will be refered to herein are: BYTE : a single byte of data (char) WORD : a two byte data field (short) LONG : a four byte data field (long) A "U" (ie. UBYTE) means unsigned. The following "typedef"s are used below: typedef LONG FRACT; /* 4 bytes */ typedef UBYTE COLOR[3]; /* 3 bytes */ typedef struct vectors { FRACT X; /* 4 bytes */ FRACT Y; /* 4 bytes */ FRACT Z; /* 4 bytes */ } VECTOR; /* 12 bytes total */ ======================================================================== SECTION 4 - ISTG sub-chunks ======================================================================== MAXF - size 2 UWORD MaxFrame; ; total frames in animation Highest frame number as it appears in the Action editor. LOOP - size 2 UWORD Looping; ; loop flags ; Bit 0 - loop animation ; Bits 1 thru 15 - reserved ======================================================================== SECTION 5 - SOBJ sub-sub-chunks ======================================================================== NAME - size 18 UBYTE Name[18]; ; a name for the staging actor (NULL terminated) Object's name as it appears in the Name & Layer requester (objects are also called actors as they move about on the stage). Used for tracking, etc. There is a NAME chunk for each (named) actor. Each NAME chunk is followed by one STGF chunk. STGF - size 2 UWORD Flags; ; "stage only" object flags ; Bit 0 - bounding box ; Bit 1 - quick edges ; Bits 2 thru 5 - reserved ; Bit 6 - axis ; Bit 7 - light source ; Bits 8 thru 15 - reserved There is a STGF chunk for each (named) actor. Each STGF chunk is followed by one LYR0 (layer number, IM30+) chunk (see below). LYR0 - size 2, IM30+ UWORD Layer; ; number indicating actor layer Actor's layer as it appears in the Name & Layer requester. Each LYR0 chunk is followed by one or more (or no one) CAMR (camera actor) or GLB? (globals) or FIL? (object actor) or LIT? (light source actor) or AXIS (axis actor) chunks (see CAMR, GLB?, FIL?, LIT? and AXIS chunks). GLB2 - variale size, IM20+ UWORD Flags; ; globals flags ; Bit 0 - genlock sky ; Bits 1 thru 15 - reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame UWORD Flags; ; reserved UWORD Blending; ; sky blending factor FRACT Density; ; star field density UWORD Flags; ; reserved UWORD Transition; ; transition frame count VECTOR Ambient; ; ambient color VECTOR Horizon; ; horizon color VECTOR PlusZenith; ; +zenith color VECTOR MinusZenith; ; -zenith color VECTOR Fog; ; fog color FRACT FogBottom; ; fog bottom FRACT FogTop; ; fog top FRACT FogLength; ; fog length UWORD Flags; ; reserved UWORD Seq0; ; global brush max seq. UWORD Flags; ; reserved UWORD Seq1; ; backdrop picture max seq. UBYTE Backdrop[256]; ; backdrop picture file name UBYTE Length; ; length of global brush file name UBYTE Global[Length]; ; global brush file name (not NULL terminated) UBYTE OptionalPad ; if name has even length (see FILE description) Please note that the above color values are stored as FRACT's and are not limited to the 0 to 255 range of the usual UBYTE color values. The "genlock sky" flag controls whether the sky will be colored, or set to the genlock color (color 0 - black) in the final picture. GLB3 - variale size, IM30+ UWORD Flags; ; reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame UWORD Flags; ; reserved UWORD Seq0; ; global brush max seq. FRACT Density; ; star field density UWORD Flags; ; reserved UWORD Transition; ; transition frame count VECTOR Ambient; ; ambient color VECTOR Horizon; ; horizon color VECTOR PlusZenith; ; +zenith color VECTOR MinusZenith; ; -zenith color VECTOR Fog; ; fog color FRACT FogBottom; ; fog bottom FRACT FogTop; ; fog top FRACT FogLength; ; fog length UWORD Flags; ; reserved UWORD Seq1; ; backdrop picture max seq. UBYTE Backdrop[256]; ; backdrop picture file name UBYTE Length; ; length of global brush file name UBYTE Global[Length]; ; global brush file name (not NULL terminated) UBYTE OptionalPad ; if name has even length (see FILE description) Same as above GLB2 chunk. CAMR - size 22, IM30+ UWORD Flags; ; camera flags ; Bit 0 - Y size is focus distance ; Bit 1 - Y size is screen distance ; Bit 2 - ap. size is DOF width mult. ; Bit 3 - ap. size is actual size ; Bit 4 - eye sep. is screen width ; Bit 5 - eye sep. is actual size ; Bits 6 thru 15 - reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame FRACT Multiplier; ; distance multiplier FRACT Aperture; ; aperture size DOF FRACT Separation; ; eye separation 3DS UWORD Flags; ; reserved UWORD Transition; ; transition frame count This chunk contains the camera informations as them appear in the Camera requester. The camera looks down its own Y axis, with the top of the picture in the direction of the Z axis. The rotations are performed in the order ZXY about the camera axes. A positive angle rotates Y toward Z, Z toward X, and X toward Y for rotations about the X, Y, and Z axes respectively. In Imagine, the lens focal length is altered changing the length of the Y axis. To understand the focal length, imagine a 320 x 200 pixel rectangle perpendicular to, and centered on the camera's Y axis. Any objects in the infinite rectangular cone defined by the camera position and the 4 corners of the rectangle will appear in the picture. FILE - variable size UWORD Flags; ; actor flags ; Bit 0 - reverse cycle motion ; Bits 1 thru 15 - reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame UWORD Transition; ; transition frame count UBYTE Length; ; length of object file name UBYTE Name[Length]; ; object file name (not NULL terminated) UBYTE OptionalPad; ; appears only if the name string has an even ; length -- so the total length of the name ; "block" (length + name + pad?) comes out even Specifies the actor (normal object) informations. FIL3 - variable size, IM30+ UWORD Flags; ; actor flags ; Bit 0 - reverse cycle motion ; Bit 1 - spline interpolation ; Bit 2 - discontinuous knot ; Bits 3 thru 15 - reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame FRACT Cyc0; ; number of cycles to perform FRACT Cyc1; ; initial cycle phase FRACT Vel0; ; velocity scaling #0 FRACT Vel1; ; velocity scaling #1 UBYTE Length; ; length of object file name UBYTE Name[Length]; ; object file name (not NULL terminated) UBYTE State[18] ; state name (NULL terminated) UBYTE OptionalPad ; if name has even length (see FILE description) Note that velocity scaling sets Imagine to adjust the velocity of objects at the beginning and the end of key frame positions, entering different values from 0 to 2 will make objects ease in and ease out. LITE - size 22 UWORD Flags; ; light source flags ; Bit 0 - spherical ; Bit 1 - cylindrical ; Bit 2 - conical ; Bit 3 - cast shadows ; Bit 4 - diminish intensity ; Bits 5 thru 15 - reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame VECTOR Intensity; ; light intensity UWORD Flags; ; reserved UWORD Transition; ; transition frame count This has seperate R, G & B intensities for the light actors. Note that these color values are stored as FRACT's and are not limited to the 0 to 255 range of the usual UBYTE color values so lights can be brighter than 255 255 255. LIT2 - size 22, IM30+ UWORD Flags; ; light source flags ; Bit 0 - point source ; Bit 1 - parallel rays ; Bit 2 - round shape ; Bit 3 - rectangular ; Bit 4 - cast shadows ; Bit 5 - diminish intensity ; Bit 6 - controlled falloff ; Bit 7 - no lens flare ; Bits 8 thru 15 - reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame VECTOR Intensity; ; light intensity UWORD Flags; ; reserved UWORD Transition; ; transition frame count See above LITE chunk. AXIS - size 6 UWORD Flags; ; reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame Defines start and end where the track object will appear. The Axis actor can be used as an invisible tracked object. POSN - size 12 VECTOR Position; ; the actor's position This is the end frame position (in world-space coordinates) of the actor's axes as it appears in the Tween Position requester. Legal coordinates are in the range -32768 to 32767 and 65535/65536. Currently, the ray-tracer only sees objects in the -1024 to 1024 range. Light sources, and the camera may be placed outside that range, however. POS2 - size 26, IM30+ UWORD Flags; ; position flags ; Bit 0 - spline interpolation ; Bit 1 - discontinuous knot ; Bits 2 thru 15 - reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame VECTOR Position; ; the actor's position FRACT Vel0; ; velocity scaling #0 FRACT Vel1; ; velocity scaling #1 See POSN description, this chunk replaces old POSN ones. PTH2 - variable size, IM20+ UWORD Flags; ; reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame UWORD Flags; ; reserved UWORD AccFrames ; (de)acceleration frames FRACT StartSpeed ; starting speed (units / frames) UWORD Flags; ; reserved UWORD DecFrames ; (ac)deceleration frames FRACT EndSpeed ; ending speed (units / frames) UBYTE Length; ; length of path name UBYTE Name[Length]; ; path name (not NULL terminated) UBYTE OptionalPad ; if name has even length (see FILE description) This chunk contains the path name as it appears in the Follow Path requester. ALGN - size 18 UWORD Flags; ; reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame VECTOR Alignment; ; the actor's alignment angles The rotation angles are in degrees, and specify rotations around the X, Y, and Z axes. If they are all zero, the actor's axes are aligned with the world coordinate axes. ALN2 - size 26, IM30+ UWORD Flags; ; alignment flags ; Bit 0 - spline interpolation ; Bit 1 - discontinuous knot ; Bits 2 thru 15 - reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame VECTOR Alignment; ; the actor's alignment FRACT Vel0; ; velocity scaling #0 FRACT Vel1; ; velocity scaling #1 Replaces old ALGN chunks, sets object's rotation over time. PALN - size 6 UWORD Flags; ; alignment flags ; Bit 0 - keep Y horizontal ; Bit 1 - conform group to path ; Bit 2 - conform object to path ; Bits 3 thru 15 - reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame The object is made to follow a pre-defined path as it moves, rotates and scales from one key frame to the next. TALN - variable size UWORD Flags; ; reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame FRACT StartRot; ; initial Y rotation FRACT EndRot; ; final Y rotation UBYTE Length; ; length of track name UBYTE Name[Length]; ; track name (not NULL terminated) UBYTE OptionalPad ; if name has even length (see FILE description) This chunk specifies the name of an object that the actor is "tracked" to as it moves, rotates or scales as it appears in the Track Object requester. If the name is NULL, the actor doesn't track. OSIZ - size 18 UWORD Flags; ; reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame VECTOR Size; ; actor size info The sizes are used in a variety of ways depending on the actor type. For custom objects, they are the lengths of the coordinate axes drawn in the editor. OSZ2 - size 26 UWORD Flags; ; size flags ; Bit 0 - spline interpolation ; Bit 1 - discontinuous knot ; Bits 2 thru 15 - reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame VECTOR Size; ; actor size info FRACT Vel0; ; velocity scaling #0 FRACT Vel1; ; velocity scaling #1 See above OSIZ chunk. HING - variable size UWORD Flags; ; reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame UBYTE Length; ; length of hinge name UBYTE Name[Length]; ; hinge name (not NULL terminated) UBYTE OptionalPad ; if name has even length (see FILE description) This is Imagine's hinge data as it appears in the Hinge requester. ASSC - variable size, IM30+ UWORD Flags; ; reserved UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame UBYTE Length; ; length of associate name UBYTE Name[Length]; ; associate name (not NULL terminated) UBYTE OptionalPad ; if name has even length (see FILE description) Causes object to tack onto the associated object and keep its relative distance, rotation and so on. This replaces old HING chunks. SPFX - variable size UWORD Flags; ; see below UWORD StartFrame; ; starting frame UWORD EndFrame; ; ending frame UBYTE Length; ; length of effect name UBYTE Name[Length]; ; effect name (not NULL terminated) UBYTE OptionalPad ; if name has even length (see FILE description) UBYTE FxData[size]; ; effect data - variable size This is the effect 1 data chunk. The Name string describes what kind of information is actually stored within the FxData[] array. This one and the Flags are interpreted as follows depending upon the effect type: animbrsh - animated brush effect ; animbrsh flags ; Bits 0 thru 15 - reserved UWORD Flags; ; reserved UWORD FirstFrame; ; first frame UWORD Flags; ; reserved UWORD LastFrame; ; last frame UBYTE Brush[256]; ; brush name (264 bytes total) baloon - ballon effect ; baloon flags ; Bit 0 - inside within object ; Bit 1 - circumscribe about object ; Bit 2 - use average radius ; Bit 3 - set radius to ; Bit 4 - use average radius ; Bit 5 - reverse baloon timing ; Bit 6 - return to original shape ; Bits 7 thru 15 - reserved FRACT Radius; ; ballon radius (4 bytes total) boing2 - boing effect ; boing flags ; Bit 0 - squash to +(XY or Z) ; Bit 1 - squash to center ; Bit 2 - squash to -(XY or Z) ; Bit 3 - X axis ; Bit 4 - Y axis ; Bit 5 - Z axis ; Bits 6 thru 15 - reserved FRACT Shrink; ; shrink factor LONG Count; ; number of times (8 bytes total) explode - explode effect ; explode flags ; Bit 0 - spherical ; Bit 1 - radial ; Bit 2 - linear ; Bit 3 - X axis ; Bit 4 - Y axis ; Bit 5 - Z axis ; Bit 6 - return to original positions ; Bit 7 - reverse explosion timing ; Bits 8 thru 15 - reserved FRACT Distance; ; explosion distance FRACT Angle; ; explosion angle FRACT Scaling; ; triangle scaling FRACT MinRotations; ; minimum number of triangle rotations FRACT MaxRotations; ; maximum number of triangle rotations LONG Seed; ; random number seed (24 bytes total) firewrks - fireworks effect ; explode flags ; Bit 0 - spherical ; Bit 1 - radial ; Bit 2 - linear ; Bit 3 - X axis ; Bit 4 - Y axis ; Bit 5 - Z axis ; Bit 6 - make faces sparkle ; Bits 7 thru 15 - reserved FRACT Distance; ; explosion distance FRACT Angle; ; expansion angle FRACT Scaling; ; triangle scaling FRACT MinRotations; ; minimum number of triangle rotations FRACT MaxRotations; ; maximum number of triangle rotations FRACT Count; ; frame count for expansion FRACT Fall; ; distance to fall by end LONG Seed; ; random number seed (32 bytes total) flash - flash effect ; flash flags ; Bit 0 - start on ; Bit 1 - start off ; Bits 2 thru 15 - reserved UWORD Flags; ; reserved UWORD OnFrames; ; on frames UWORD Flags; ; reserved UWORD OffFrames; ; off frames (8 bytes total) grow - grow effect ; grow flags ; Bit 0 - align Y topath direction ; Bit 1 - keep X in path's XY plane ; Bit 2 - mirror ends ; Bit 3 - time reversed ; Bit 4 - sharp extrusion ; Bits 5 thru 15 - reserved FRACT YRotation; ; Y rotation FRACT XScaling; ; X scaling FRACT ZScaling; ; Z scaling FRACT XTranslate; ; X translate FRACT ZTranslate; ; Z translate (20 bytes total) particle - particle effect ; particle flags ; Bit 0 - delayed ; Bit 1 - rain ; Bit 2 - bounce ; Bit 3 - taper ; Bit 4 - emission ; Bit 5 - reverse timing ; Bit 6 - return to original positions ; Bits 7 thru 15 - reserved FRACT Distance; ; travel distance FRACT Scaling; ; triangle scaling FRACT Delay; ; scaling delay FRACT MinRotations; ; minimum number of rotations FRACT MaxRotations; ; maximum number of rotations FRACT HVelocity; ; time to terminal horizontal velocity FRACT Gravity; ; gravitational constant LONG Seed; ; random number seed FRACT Elasticity; ; elasticity FRACT ZVelocity; ; time to terminal Z velocity FRACT Ground; ; ground Z coordinate FRACT Speed; ; speed factor FRACT MinAngleZ; ; minimum angle from Z FRACT MaxAngleZ; ; maximum angle from Z FRACT MinAngleX; ; minimum angle from X FRACT MaxAngleX; ; maximum angle from X FRACT WindSpeed; ; wind speed FRACT WindAngle; ; wind angle FRACT WindStart; ; wind start FRACT WindStop; ; wind stop FRACT Emission; ; emission amount UBYTE Subgroup[18]; ; subgroup name (NULL terminated) UWORD Flags; ; reserved (108 bytes total) ripple - ripple effect ; ripple flags ; Bit 0 - radial around Z ; Bit 1 - linear along X ; Bits 2 thru 15 - reserved FRACT Length; ; wave length FRACT Amplitude; ; Z amplitude FRACT Distance; ; travel distance LONG Ripples; ; ripple count (16 bytes total) rotate2 - rotate effect ; rotate2 flags ; Bit 0 - X axis ; Bit 1 - Y axis ; Bit 2 - Z axis ; Bits 3 thru 15 - reserved FRACT Degrees; ; rotation degrees (4 bytes total) shredder - shredder effect ; shredder flags ; Bit 0 - whole object as parts ; Bit 1 - use def. subgroups as parts ; Bit 2 - la machine ; Bit 3 - bounce particle ; Bit 4 - flip on bounce ; Bit 5 - use maximal bounding sphere ; Bit 6 - use minimal bounding sphere ; Bit 7 - use average bounding sphere ; Bits 8 thru 15 - reserved LONG MaxTriangles; ; maximum number of triangles in group UBYTE Subgroup[18]; ; subgroup name (NULL terminated) UWORD Flags; ; reserved FRACT StartTime; ; start time FRACT EndTime; ; end time FRACT ExplosionDelay; ; explosion timing delay LONG HoldAt; ; hold at FRACT Ground; ; ground Z position FRACT MinElasticity; ; minimum elasticity FRACT MaxElasticity; ; maximum elasticity FRACT MinVelocity; ; minimum initial velocity range FRACT MaxVelocity; ; maximum initial velocity range FRACT MinRotations; ; minimum triangle rotations FRACT MaxRotations; ; maximum triangle rotations FRACT MinTrajectory; ; minimum particle trajectory FRACT MaxTrajectory; ; maximum particle trajectory FRACT MinScaling; ; minimum final scaling factor range FRACT MaxScaling; ; maximum final scaling factor range FRACT Acceleration; ; gravitational acceleration FRACT UnitsPerMeter; ; Imagine units per meter LONG Seed; ; random number seed (96 bytes total) spike - spike effect ; spike flags ; Bit 0 - linearly along Z ; Bit 1 - cylindrically around Z ; Bit 2 - radially from axis ; Bit 3 - restrict to integral cycles ; Bit 4 - reverse spike timing ; Bit 5 - return to starting shape ; Bits 6 thru 15 - reserved FRACT MinDistance; ; minimum spike distance FRACT MaxDistance; ; maximum spike distance FRACT MinCycles; ; minimum spike cycles FRACT MaxCycles; ; maximum spke cycles FRACT Dispersion; ; dispersion adjust LONG Seed; ; random number seed (24 bytes total) sway - group sway effect ; sway flags ; Bit 0 - random axis ; Bit 1 - Z axis ; Bit 2 - X axis ; Bit 3 - Y axis ; Bit 4 - restrict to int. gyrations ; Bits 5 thru 15 - reserved FRACT MinGyrations; ; minimum number of gyrations FRACT MaxGyrations; ; maximum number of gyrations FRACT MinAngle; ; minimum gyration angle FRACT MaxAngle; ; maximum gyration angle LONG Seed; ; random number seed (20 bytes total) tumble - tumble effect ; tumble flags ; Bit 0 - random axis ; Bit 1 - Z axis ; Bits 2 thru 15 - reserved FRACT MinRotations; ; minimum number of rotations FRACT MaxRotations; ; maximum number of rotations LONG Seed; ; random number seed (12 bytes total) S?FX - variable size See SPFX above chunk. Up to four special effects can be applied to an object at one time. ======================================================================== SECTION 6 - PC (80x86 CPU) notes ======================================================================== The IFF file format originated on machines in which the byte order for LONG (4 byte) and WORD (2 byte) data is "most significant byte first". This concept has been preserved in the "PC" versions of Imagine. What it means, is that if you are writing code for the "other" type of CPU (80386 code, for example), you will need to reverse the byte ordering in (U)LONG, FRACT, and (U)WORD data wherever it appears (eg. the FRACTs in a VECTOR structure must be (separatly) byte reversed... the size field following a chunk identifier is another good example). From the Imagine Object File Format document, by Scotty Kirvan. ======================================================================== SECTION 7 - IFF file format notes ======================================================================== In case you are unfamiliar with the IFF file structure, the ISTG files have the following (simple, "single FORM") IFF structure (again, from the description of Turbo Silver TDDD chunk): form_ID 4 characters: 'F','O','R','M' form_size LONG size : -- MSB(yte) first form_type 4 characters: 'I','S','T','G' chunks: chunk_ID 4 characters: eg. 'S','O','B','J' chunk_size LONG size : -- byte reversed if appropriate chunk_data 'size' bytes: chunk_pad 0 or 1 bytes: -- pad to even length if 'size' is odd Note: The "form_size" field appearing after the "form_ID" is the total length of the data that FOLLOWS it, INCLUDING the 4-byte (ISTG) id. Also the "chunk_size" fields list the size of the data in the "chunk_data" blocks that follow. In other words, the size fields when rounded up to an even number, always list the number of bytes (after the size field) to skip forward in the file if, based on the ID field preceding the size, the reader can not or does not wish to interpret the data... so, in particular, the sizes that appear DO NOT include the length of the ID and size fields themselves, and the 'form_size' DOES include 4 bytes for the 'form_type' field that follows it. ======================================================================== CLOSING - Closing statements and Disclaimer ======================================================================== Hopefully this document is useful to people out there. Once again, if there is anything you want added/changed/deleted, please e-mail as listed at the top of the document. The information presented herein What follows is a small disclaimer so no one gets sued for information that is harmful or accidentally incorrect or misleading (if you find a mistake... please send e-mail so it can be fixed). Disclaimer: There is no guarantee regarding any information presented in this document. The information may not be correct, useful or helpful. Knowledge is dangerous - use at your own risk. No warranties are made or implied, and no liability or responsibility is assumed. Good luck and enjoy. ======================================================================== END OF ISTG.DOC /\_ | | "Gabriele Scibilia aka <G>SZ ~ ArtNouveaU" | O | "minix@arsenio.disi.unige.it" | | "2:332/211.24@FidoNet.org" | O | "Imagine Mailing List,IML FAQer" ae(-_^)ue |___| _ __ ___ ______Wizard signing off