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Text File | 1993-03-01 | 36.6 KB | 1,257 lines

Proposal for a stadard 3D object format FORM OB3D (revision 1) ------------------------ by Roberto Speranza This is a modified specification of the OB3D FORM, proposed a few weeks ago. Much concern was raised about the earlier FORM's inflexibility. I have tried to address that here by adding flexibility to the majority of the chunks by making them tag-based. This will define what I consider to be the bare minimum I require of this FORM for my own program plus anything I can think of to accomodate other programs I am aware of as well suggestions posed by others. Additional chunks or additional tags for chunks currently defined in this proposal will have to be discussed as soon as possible after this posting. I want this minimum definition approved so that I can begin the task of re-writing my reader/writer software to handle all of this. To add the flexibility requested, the reader software has to increase in complexity somewhat. Here are a few highlights of the revised FORM: - almost all chunks are tag-based - SPLN chunk updated to handle NURBs (non-uniform rational B-Splines) - SURF and NURB chunk merged with a new chunk, PRIM, which will contain ALL primitives; polygons, bicubic surfaces, NURB surfaces, and other primitives such as spheres, cones, etc. - precision concerns have been eliminated by the addition of variables to the PREF chunk that are designed to inform the reader software of the precision of floats used in the file - the addition of a MACR chunk for stroing ASCII macros such as AREXX macros or scripts The following is a list of chunks and their descriptions followed by a detailed description of all the tags currently defined. ----------------------------------------------------------------------------- FORM struct FORMstruct { ULONG ID; ULONG Size; } OB3D PREF (optional) struct PREFstruct { ULONG Id; ULONG Size; UWORD preflines; ULONG prefsize; UBTE Prefs[prefsize]; UBTE pad; /* to make chunk even length, if necessary */ } The character array Prefs consists of lines of ASCII text terminated by newlines (\n). The NumLines field tells you how many lines in case you want to read it in a line at a time. Each line takes the following form: variable=value(s) (more than one value will be separated by spaces) This type of preferences layout was selected for generality and easy expansion. This will also allow for program preferences to be stored in IFF form. If this chunk is present, it will contain preferences for the reader code as well as any program preferences. Here are some variables to start us off: Variable Suggested Value(s) -------- ------------------ TIMEUNITS FRAMES or SECONDS depending on application FRAMERATE 60 TIMEFLOAT IEEESINGLE (32 bit) CHARSTRING ( length (UWORD) + length characters ) (not null terminated) ULONGINT (32 bit) TIMEBASE 1 (number to divide TIMEFLOAT by to get value in TIMEUNITS) (primarily for specifying how to convert ULONGINTS to a floating point quantity if desired) STARTFRAME 1 (or whatever) ATTFLOAT IEEESINGLE (32 bit) CHARSTRING ( length (UWORD) + length characters ) (not null terminated) UBTE ( 8 bit) UWORDINT (16 bit) ULONGINT (32 bit) ATTBASE 1 (number to divide ATTFLOAT by to get value in TIMEUNITS) (primarily for specifying how to convert non-floating point quantities to a floating point quantity if desired) FLOAT IEEESINGLE (32 bit) CHARSTRING ( length (UWORD) + length characters ) (not null terminated) COORFLOAT IEEESINGLE (32 bit) IEEEDOUBLE (64 bit) IEEEEXTENDED (96 bit) This is supported by the MC6888x FPUs. Manx's m.lib supports this format as a long double. CHARSTRING ( length (UWORD) + length characters ) (not null terminated) ANGLEUNITS DEGREES RADIANS DISTANCEUNITS MILLIMETRES CENTIMETRES METRES KILOMETRES INCHES FEET ARDS MILES ----------------------------------------------------------------------------- MACR (optional) struct MACRstruct { ULONG Id; ULONG Size; ULONG NumMacros; struct { UWORD namelen; /* length of name */ UBTE name[namelen]; /* name of macro */ ULONG macsize; UWORD maclines; UBTE Macro[macsize]; } [NumMacros] UBTE pad; /* to make chunk even length, if necessary */ } The character array Macro consists of lines of ASCII text terminated by newlines (\n). The field maclines tells you how many lines of text are in the macro in case you want to read it one line at a time. ----------------------------------------------------------------------------- SBAS (optional) struct SBASstruct { ULONG ID; ULONG Size; ULONG NumSBASes; struct { UWORD basisnum; /* basis number */ UWORD step; /* point step */ COORFLOAT Basis[4][4]; /* basis matrix */ } [NumSBASes]; UBTE pad; /* to make chunk even length, if necessary */ } This chunk is only required if bicubic surfaces or splines are stored in the file. This chunk defines the basis matrix to convert the control points of the spline to coefficients for the cubic equation that describes the spline. The step parameter dictates how to apply the basis matrix to splines which use more than 4 control points but are still cubic in nature (like more than one linked up together). I believe three basis numbers should be reserved for these common splines: Number Spline Type ------ ----------- 0 Bezier spline 1 Uniform non-rational B-spline 2 Catmull-Rom spline I selected these spline types because they are the most common ones used in modellers and CAD packages. Any other type can be defined at will, allowing for custom splines. ----------------------------------------------------------------------------- TRGB (optional) struct TRGBstruct { ULONG ID; ULONG Size; ULONG NumTRGBs; struct { UWORD NumColours; /* number of components in colour model */ FLOAT ToRGB[NumColours][3]; /* transformation matrix */ } [NumTRGBs]; UBTE pad; /* to make chunk even length, if necessary */ } This chunk is optional if all colour data is specified using the RGB colour model. The transformation matrix for RGB colour data is simply a 3X3 identity matrix. For any other colour model, this chunk should be present in order to specify the number of components used for colours as well as the transformation matrix used to multiply the colours in the file to RGB. This should suffice for most colour models. example: [t00 t01 ... t0n][c0] = [R] |t10 t11 ... t1n||c1| |G| [t20 t21 ... t2n]|..| [B] [..] [cn] ----------------------------------------------------------------------------- VERT (optional only when HIER chunk is present else not included) struct VERTstruct { ULONG Id; ULONG Size; ULONG NumVERTs; struct { ULONG numtags; struct { ULONG tagtype; UBTE data[tagsize]; } [numtags] } [NumVERTs]; UBTE pad; /* to make chunk even length, if necessary */ } The VERT chunk stores all vertex information. This structure is now tag-based to allow for future expansion and flexibility. The following tags are applicable to the VERT chunk: OB3D_Parent OB3D_Clone OB3D_RelSurf OB3D_TimeStamp OB3D_Cycle OB3D_Interpolation OB3D_Script VERT_Position VERT_Velocity ----------------------------------------------------------------------------- EDGE (optional; if VERT chunk is missing, it is not included) struct EDGEstruct { ULONG ID; ULONG Size; ULONG NumEDGEs; struct { ULONG points[2]; /* index to two points of edge */ ULONG numtags; /* hook for future tags */ struct { ULONG tagtype; UBTE data[tagsize]; } [numtags] } [NumEDGEs] UBTE pad; /* to make chunk even length, if necessary */ } The EDGE chunk stores all edges for programs that use a wireframe representation in their editors or renderers. Programs that do not require edges do not need to store this chunk in their files. This will force programs who require edges to reconstruct the edges or represent the objects with a bounding box. The tags that are applicable to this chunk are: none at this time ----------------------------------------------------------------------------- SPLN (optional; if VERT chunk is missing, it is not included) struct SPLNstruct { ULONG ID; ULONG Size; ULONG NumSPLNs; struct { ULONG numpts; /* number of points */ ULONG points[numpts]; /* control pts indices */ ULONG numtags; struct { ULONG tagtype; UBTE data[tagsize]; } [numtags] } [NumSPLNs] UBTE pad; /* to make chunk even length, if necessary */ } The SPLN chunk is used to store any spline information. By using various tags, any cubic spline or NURB (non-uniform rational B-spline) can be stored. The following is a list of tags that can be used for the SPLN chunk: SPLN_Basis SPLN_NURB_Order SPLN_TrimSurf SPLN_NURBKnots SPLN_NURBWeights NOTE: (for cubic splines only) numpts=4+n*basisstep where n = any integer from 0 to infinity bassistep = the step value of the basis matrix used for the spline ----------------------------------------------------------------------------- PRIM (optional unless HIER and VERT chunk are missing because it is not included) struct PRIMstruct { ULONG ID; ULONG Size; ULONG NumPRIMs; ULONG numtags; struct { ULONG tagtype; UBTE data[tagsize]; } [NumPRIMs]; UBTE pad; /* to make chunk even length, if necessary */ } Bicubic surfaces have played a very important role of late in CAD and commercial graphics. Applications on the Amiga are now starting to model objects using bicubic surfaces making this chunk a necessity. The importance of the NURB (non-uniform rational B-Spline) has come about due to the need to represent conics and quadrics accurately using parametric surfaces. Bicubic surfaces can only approximate these surfaces but NURB surfaces can represent them exactly and enjoy the flexibility of B-splines as well. By using various tags, this chunk can store any primitive including bicubic surfaces, NURB surfaces or polygons. This chunk will be used to specify primitive objects. It is tag-based, allowing for expansion as different primitives are supported in the future. The following tags are applicable to this chunk: OB3D_Parent OB3D_TimeStamp OB3D_Cycle OB3D_Interpolation OB3D_Script PRIM_Points PRIM_PolySmoothing PRIM_SurfBasis PRIM_NURBOrder PRIM_Contours PRIM_NURBKnots PRIM_NURBWeights PRIM_TextureSpace PRIM_RectangularSolid PRIM_Ellipsoid PRIM_Prism PRIM_SurfaceRevolution PRIM_SemiInfiniteSpace PRIM_RiSphere PRIM_RiCone PRIM_RiDisk PRIM_RiCylinder PRIM_Hyperboloid PRIM_RiParaboloid PRIM_RiTorus ----------------------------------------------------------------------------- HIER (optional; excluded if file is missing both VERT and LAMP chunks) struct HIERstruct { ULONG ID; ULONG Size; ULONG NumHiers; /* Number of Hierarchies in chunk */ struct { ULONG numtags; struct { ULONG tagtype; UBTE data[tagsize]; } [numtags] } [NumHiers]; UBTE pad; /* to make chunk even length, if necessary */ } The Hierarchy chunk is used to describe the relationships between objects, paths and lamps. The following tags are applicable to this chunk: OB3D_Name OB3D_Parent OB3D_Clone OB3D_TimeStamp OB3D_Cycle OB3D_Interpolation OB3D_Texture OB3D_Script HIER_Type HIER_CustomTypeName HIER_HierStatus HIER_BoundingBox HIER_LampType HIER_Size HIER_Shear HIER_LocalOrigin HIER_Velocity HIER_Axes HIER_PRAngles HIER_XZAngles HIER_Translate HIER_RelPRAngles HIER_RelXZAngles ----------------------------------------------------------------------------- ATTR (optional if TXTR is not present) struct ATTRstruct { ULONG ID; ULONG size; ULONG NumATTRs; struct { ULONG numtags; struct { ULONG tagtype; UBTE data[tagsize] } [numtags] } [NumATTRs] UBTE pad; /* to make chunk even length, if necessary */ } The ATTR chunk stores all information about attributes. The following tags are used for this chunk: OB3D_Name OB3D_TimeStamp OB3D_Cycle OB3D_Interpolation ATTR_ColourSize ATTR_Diffuse ATTR_Reflect ATTR_Transmit ATTR_Ambient ATTR_Illumin ATTR_Opacity ATTR_IndexRefract ATTR_SpecHighLight ATTR_PhongHighLight ATTR_HighlightColour ATTR_LightIntensity ATTR_LightDirection ATTR_ConeLight ATTR_AreaLight ATTR_Fog ATTR_DepthCue ATTR_EnvironIllumin ATTR_EnvIndexRefract I am sure there are attributes that have been missed. Further discussion and debate over this specification should result in the missing attributes being defined. ----------------------------------------------------------------------------- TXTR (optional) struct TXTRstruct { ULONG ID; ULONG Size; ULONG NumTXTRs; struct { UWORD namelen; UBTE name[namelen]; /* name of texture */ ULONG numtags; /* number of tags for texture */ struct { ULONG tagtype; UBTE data[tagsize]; } [numtags] } [NumTXTRs]; UBTE pad; /* to make chunk even length, if necessary */ } The TXTR chunk stores all information about textures. The following tags are used for this chunk: OB3D_Name OB3D_TimeStamp OB3D_Cycle OB3D_Interpolation OB3D_Texture OB3D_Script TXTR_RenderType TXTR_Space TXTR_BoundingBox TXTR_Center TXTR_BitMap TXTR_Checker TXTR_Gradient TXTR_Brick TXTR_Wood TXTR_Wave TXTR_BumpMap I have just defined some textures to start us off. I attempted to define some common textures used by most amiga rendering programs. Further discussion and debate over this specification should result in the missing attributes being defined. ----------------------------------------------------------------------------- BACK (optional) struct BACKstruct { ULONG ID; ULONG Size; ULONG numtags; struct { ULONG tagtype; UBTE data[tagsize]; } [numtags] } The BACK chunk is used to store all information required to describe the background of a rendered scene. As needs expand, tags can be added to accomodate additional information. BACK_GroundTexture BACK_SkyTexture BACK_EnviroTexture ----------------------------------------------------------------------------- OBSV (optional) struct OBSVstruct { ULONG ID; ULONG Size; ULONG NumOBSVs; struct { ULONG numtags; struct { ULONG tagtype; UBTE data[tagsize]; } [numtags] } [NumOBSVs] } The OBSV chunk stores all parameters necessary to describe the view. The following tags are applicable to this chunk: OB3D_TimeStamp OB3D_Cycle OB3D_Interpolation OBSV_ObserverHierarchy OBSV_TargetHierarchy OBSV_Observer OBSV_Target OBSV_Distance OBSV_Orientation OBSV_Tilt OBSV_FieldofView OBSV_RecordingMedium OBSV_FocalLength OBSV_Aperture OBSV_StopNumber OBSV_ShutterSpeed OBSV_Separation ----------------------------------------------------------------------------- DISP (optional) struct DISPstruct { ULONG ID; ULONG Size; ULONG NumDisps; struct { ULONG numtags; struct { ULONG tagtype; UBTE data[tagsize]; } [numtags] } [NumDisps] } The DISP chunk is to be used to save the various displays programs use. The tags used for this chunk are: OBSV_Observer OBSV_Target OBSV_Distance OBSV_Orientation OBSV_Tilt OBSV_FieldofView OBSV_RecordingMedium OBSV_FocalLength OBSV_Aperture OBSV_StopNumber OBSV_ShutterSpeed OBSV_Separation DISP_WindowParms DISP_ViewStatus DISP_FrameRate ----------------------------------------------------------------------------- Tags for the OB3D FORM ---------------------- Label Offset Data Description ---- ----------- OB3D_TagBase+ (0x00000000) OB3D_Name 0 UWORD namelen; UBTE name[namelen]; name of entity (not null terminated) OB3D_Parent 1 ULONG parent; index to parent entity OB3D_Clone 2 ULONG clone; index to clone entity OB3D_RelSurf 3 ULONG relsurf; index to clone entity OB3D_TimeStamp 4 TIMEFLOAT timestamp; timestamp for tags that follow OB3D_Cycle 5 TIMEFLOAT start, TIMEFLOAT length; start ad length of cycle OB3D_Interpolation 6 ULONG status; interpolate parameters to next key-frame possible status flags are: Label Value Description ----- ----- ----------- 0x00000800 reserved for interpolation to flags not yet contemplated 0x00000010 PVSPLINE 0x00000008 spline parameters to next key-frame using positions and velocities PSPLINE 0x00000004 spline parameters to next key-frame using positions only LINEAR 0x00000002 linearly interpolate parameters to next key-frame OFF 0x00000001 turn off OB3D_Texture 7 ULONG texture; index to entity's texture OB3D_Script 8 UWORD namelen; UBTE name[namelen]; name of script ----------------------------------------------------------------------------- VERT_TagBase+ (0x00010000) VERT_Position 0 COORFLOAT position[3]; position of vertex at the indicated key-frame VERT_Velocity 1 COORFLOAT velocity[3]; velocity of vertex at the indicated key-frame ----------------------------------------------------------------------------- SPLN_TagBase+ (0x00020000) SPLN_Basis 0 UWORD basisnum; index to basis matrix for cubic spline SPLN_NURB_Order 1 UWORD order; order of NURB SPLN_TrimSurf 2 ULONG trimsurf; index to surface that this spline trims SPLN_NURBKnots 3 UWORD num; FLOAT knots[num]; array of knot values for NURB SPLN_NURBWeights 4 COORFLOAT weights[numpts]; array of weights for control points ----------------------------------------------------------------------------- PRIM_PolyTagBase+ (0x00030000) PRIM_Points 0 ULONG numpts; ULONG points[numpts]; array of control point indices (for NURB and bicubic surfaces, numpts = upts*vpts where there are vpts rows of upts indices) PRIM_PolySmoothing 1 UWORD smoothing; The smoothing variable describes the type of normal smoothing to use when rendering polygons. The following values are valid: 0 - no smoothing 1 - Phong normal smoothing PRIM_SurfTagBase+ (0x00031000) PRIM_SurfBasis 5 UWORD ubasis, vbasis; basis index for u and v direction PRIM_NURBOrder 1 UWORD uorder, vorder; order of NURB for both u and v directions PRIM_Contours 2 UWORD ucon, vcon; contours for both u and v direction PRIM_NURBKnots 3 UWORD unum, vnum; FLOAT uknots[unum]; FLOAT vknots[vnum]; NURB knots for both u and v direction PRIM_NURBWeights 4 COORFLOAT weights [numupts*numvpts]; array of weights for control points PRIM_TextureSpace 5 FLOAT umin, vmin, umax, vmax; Mapping limits in texture space PRIM_PrimTagBase+ (0x00032000) PRIM_RectangularSolid 0 orientation/size/position determined by parent hierarchy PRIM_Ellipsoid 1 orientation/size/position determined by parent hierarchy PRIM_Prism 2 ULONG hierindex; extrusion of any contour by a specified length index to hierarchy containing the contour and parent hierarchy determines the size PRIM_SurfaceRevolution 3 UWORD axis; 0 - X, 1 - , 2 - Z FLOAT anglerev; a contour spun around a specific axis PRIM_SemiInfiniteSpace 4 COORFLOAT vec1[3], vec2[3]; a plane whose normal (right hand rule) defines the direction in which the space extends PRIM_RiSphere 5 COORFLOAT radius; COORFLOAT zmin, zmax; FLOAT thetamax; sphere primitive ala RenderMan PRIM_RiCone 6 COORFLOAT radius; COORFLOAT height; FLOAT thetamax; cone primitive ala RenderMan PRIM_RiDisk 7 COORFLOAT radius; COORFLOAT height; FLOAT thetamax; disk primitive ala RenderMan PRIM_RiCylinder 8 COORFLOAT radius; COORFLOAT zmin, zmax; FLOAT thetamax; cylinder primitive ala RenderMan PRIM_Hyperboloid 9 COORFLOAT point1[3], point2[3]; FLOAT thetamax; hyperboloid primitive ala RenderMan PRIM_RiParaboloid 10 COORFLOAT radiusmax; COORFLOAT zmin, zmax; FLOAT thetamax; cylinder primitive ala RenderMan PRIM_RiTorus 11 COORFLOAT majorrad, minorrad; COORFLOAT phimin, phimax; FLOAT thetamax; cylinder primitive ala RenderMan for details of the RenderMan primitives above, consult pp. 62-63 of the RenderMan Companion by Steve Upstill (Publisher: Addison Wesley) ----------------------------------------------------------------------------- HIER_TagBase+ (0x00040000) HIER_Type 0 ULONG type; type of hierarchy Currently, the following types are supported: Type Label Description ---- ----- ----------- 0 HT_EMPT empty 1 HT_PATH path 2 HT_OBJECT object defined using vertices 4 HT_CSGOBJECT object defined using PRIMitives 5 HT_LAMP lamp and possibly objects (for compatibility with existing software) 6 HT_CUSTOM custom object (type name supplied with tag) 10 HT_SSOBJECTS objects for internal use only HIER_CustomTypeName 1 UWORD namelen; UBTE name[namelen]; name of custom hierarchy type (not null terminated) HIER_HierStatus 2 ULONG status; status of hierarchy Label Value Description ----- ----- ----------- 0x00800000 reserved for future use to 0x00010000 HEEDGES 0x00008000 draw object during operation HEEXTENT 0x00004000 draw extent during operation HNEDGES 0x00002000 draw object when refreshing HNEXTENT 0x00001000 draw extent when refreshing 0x00000800 reserved for future use to 0x00000080 HUNION 0x00000040 object Boolean OR HINTERSECT 0x00000020 object Boolean AND HSUB 0x00000010 object subtract HOFF 0x00000008 object/hierarchy is off in editor HTPEDIT 0x00000004 object surface trim curve points are editable HEDIT 0x00000002 object surface control points are editable HSELECT 0x00000001 object is selected HIER_BoundingBox 3 FLOAT low[3], high[3]; bounding box of hierarchy HIER_LampType 4 UWORD lamptype; lamp type/behaviour 0 - directional light source 1 - point source (inverse square law) 2 - conical light source 3 - cylindrical light source 4 - area light source HIER_Size 5 COORFLOAT size[3]; size of axes HIER_Shear 6 COORFLOAT shear[6]; size of shear components 0 - X-axis -component 1 - X-axis Z-component 2 - -axis X-component 3 - -axis Z-component 4 - Z-axis X-component 5 - Z-axis -component HIER_LocalOrigin 7 COORFLOAT locorig[3]; position wrt. parent's space HIER_Velocity 8 COORFLOAT velocity[3]; velocity wrt. parent's space HIER_Axes 9 COORFLOAT axes[3][3]; normalized axes row 0 - X axis row 1 - axis row 2 - Z axis HIER_PRAngles 10 FLOAT yprang[3]; angles for yaw, pitch and roll HIER_XZAngles 11 FLOAT xyzang[3]; angles for X, and Z-axis rotations in this order HIER_Translate 12 COORFLOAT trans[3]; translate last local origin using this vector HIER_RelPRAngles 13 FLOAT yprang[3]; relative angles for yaw, pitch and roll from last key-frame HIER_RelXZAngles 14 FLOAT xyzang[3]; relative angles for X, and Z-axis rotations in this order from last key-frame ----------------------------------------------------------------------------- OBSV_TagBase+ (0x00050000) OBSV_ObserverHierarchy 0 ULONG index; index to observer hierarchy OBSV_TargetHierarchy 1 ULONG index; index to target hierarchy OBSV_Observer 2 COORFLOAT Observer[3]; location of observer/camera OBSV_Target 3 COORFLOAT Target[3]; location of target OBSV_Distance 4 COORFLOAT Distance[3]; distance to focal plane OBSV_Orientation 5 FLOAT yprang[3]; angles for yaw, pitch and roll of camera OBSV_Tilt 6 FLOAT tilt; tilt angle of camera OBSV_FieldofView 7 FLOAT separation; separation (for stereo) OBSV_RecordingMedium 8 FLOAT recwidth, recheight; width/height of recording medium ie. 35mm film, CCD, etc. OBSV_FocalLength 9 FLOAT FocalLength; focal length of lens : mm OBSV_Aperture 10 FLOAT aperture; size of aperture in mm OBSV_StopNumber 11 FLOAT stopnum; stop number OBSV_ShutterSpeed 12 FLOAT shutspeed; shutter speed OBSV_Separation 13 FLOAT separation; view separation (for stereoscopic views) ----------------------------------------------------------------------------- DISP_TagBase+ (0x00060000) DISP_WindowParms 0 WORD left, top, width, height; parameters of windows in virtual screen coordinates DISP_ViewStatus 1 ULONG viewstatus; status of display Label Value ----- ----- VOLUMERENDER 0x00000800 volume rendering RADIOSIT 0x00000400 radiosity RATRACE 0x00000200 raytracing PHONGSHADE 0x00000100 Phong shading GORAUDSHADE 0x00000080 Goraud shading SOLIDMODEL 0x00000040 solid shading HIDDENLINE 0x00000020 hidden line removal WIREFRAME 0x00000010 wireframe ZBUFFER 0x00000008 z-buffer SCANLINE 0x00000004 scanline XSPECS 0x00000002 stereo with XSPECS (interlaced) PERSPECT 0x00000001 perspective on DISP_FrameRate 2 FLOAT framerate; framerate in display ----------------------------------------------------------------------------- BACK_TagBase+ (0x00070000) BACK_GroundTexture 0 ULONG texindex; index to ground texture BACK_SkyTexture 1 ULONG texindex; index to sky texture BACK_EnviroTexture 2 ULONG texindex; index to environment texture ----------------------------------------------------------------------------- ->Light Characteristics<- ATTR_LightTagBase+ (0x00080000) ATTR_ColourSize 0 UWORD cols; number of colour components for attribute ATTR_Diffuse 1 ATTFLOAT diffuse[cols]; diffuse colour components ATTR_Reflect 2 ATTFLOAT reflect[cols]; reflected colour components ATTR_Transmit 3 ATTFLOAT transmit[cols]; transmitted colour components ATTR_Ambient 4 ATTFLOAT ambient [cols]; ambient colour components ATTR_Illumin 5 ATTFLOAT illumin [cols]; illuminated colour components ATTR_Opacity 6 ATTFLOAT opacity; illuminated colour components ATTR_IndexRefract 7 FLOAT indexref[cols]; indices or refraction for each colour components 7-14 reserved for future light characteristics ->Highlight Parameters<- ATTR_HighlightTagBase+ (0x00081000) ATTR_SpecHighLight 0 ATTFLOAT specularpercent, roughness; parameters for specular highlights ATTR_PhongHighLight 1 ATTFLOAT phongpercent, phongsize; parameters for Phong highlights ATTR_HighlightColour 2 ATTFLOAT highlight[cols]; highlight colour components 18-19 reserved for future highlight types ->Lamp Attributes<- ATTR_LampTagBase+ (0x00082000) ATTR_LightIntensity 0 ATTFLOAT intensity; intensity of light source ATTR_LightDirection 1 COORFLOAT dir[3]; direction of light source ATTR_ConeLight 2 FLOAT coneangle, conedeltaangle, beamdistrib; parameters for conic light source ATTR_AreaLight 3 UWORD width, height; sample grid size for area light source 24-30 reserved for future lamp characteristics ->Environmental Attributes<- ATTR_EnviroTagBase+ (0x00083000) ATTR_Fog 31 ATTFLOAT col[cols]; fog parameters FLOAT mindist; distance to start fog and fog colours ATTR_DepthCue 32 ATTFLOAT col[cols]; depth cue parameters FLOAT mindist; FLOAT maxdist; min. and max. distance over which depth cueing will occur ATTR_EnvironIllumin 33 ATTFLOAT illum[cols]; ambient illumination color components ATTR_EnvIndexRefract 34 FLOAT index; index of refraction of the environment 35-50 reserved for future environment attributes ----------------------------------------------------------------------------- TXTR_TagBase+ (0x00090000) TXTR_Default 0 ULONG attindex; index to default attribute serve as a base attribute to provide defaults to values not modified by additional texture tags TXTR_RenderType 1 ULONG rendertype; tags following this one will define textures for the specified type of rendering The following are valid rendertypes: TXTR_SOLIDSHADING 0x00000001 TXTR_GORAUDSHADING 0x00000002 TXTR_PHONGSHADING 0x00000004 TXTR_ZBUFFER 0x00000008 TXTR_RATRACING 0x00000010 TXTR_RADIOSIT 0x00000020 TXTR_VOLUMESHADING 0x00000040 TXTR_Space 2 UWORD size; the size of texture space TXTR_BoundingBox 3 COORFLOAT low[size], high[size]; bounding box of n-dimensional texture space TXTR_Center 4 COORFLOAT cen[size]; limits of n-dimensional texture space TXTR_BitMap 5 UWORD namelen; UBTE name[namelen]; (not null terminated) UWORD channel; bitmap texture TXTR_AttribTagBase+ (0x00091000) TXTR_Checker 0 COORFLOAT scale[size]; ULONG att[2]; checker texture TXTR_Gradient 1 ULONG att[size*2]; gradient texture TXTR_Brick 2 COORFLOAT mortscale; thickness of mortar COORFLOAT scale[size]; size of brick ULONG attindex[2]; brick texture TXTR_Wood 3 float ringscale; ULONG lightcolour, indices to attributes for light-coloured wood, darkcolour; dark-coloured wood and base attributes TXTR_NormalTagBase+ (0x00092000) TXTR_Wave 0 BOOL displacement; FLOAT phase,amplitude, wavelength,damping; wave normal mapping TXTR_BumpMap 1 FLOAT minheight, maxheight; bump map texture (requires TXTR_BitMap tag to precede it) -------------------------------------------------------------------------- SURF-X_TagBase+ (0x000A0000) reserved for SurF-X program-specific tags xxxxxx_TagBase+ (0x000B0000)-(0xFFFF0000) reserved for other program-specific tags or tags for new chunks added to this spec in the future these sections can include private tags designed for internal use such as cutting and pasting. tags that are general enough for all programs should go in one of the chunk sections if appropriate