NAME - size 18 BYTE Name; ; a name for the object. Used for camera tracking, specifying story paths, etc. SHAP - size 4 WORD Shape; ; number indicating object type WORD Lamp; ; number indicating lamp type Lamp numbers are composed of several bit fields: Bits 0-1: 0 - not a lamp 1 - like sunlight 2 - like a lamp - intensity falls off with distance. 3 - unused/reserved Bits 2: 0 - non-shadow-casting light 4 - shadow-casting light Bits 3-4: 0 - Spherical light source 8 - Cylindrical light source. 16 - Conical light source. 24 - unused/reserved Shape numbers are: 0 - Sphere 1 - Stencil ; not supported by Imagine 2 - Axis ; custom objects with points/triangles 3 - Facets ; illegal - for internal use only 4 - Surface ; not supported by Imagine 5 - Ground Spheres have thier radius set by the X size parameter. Stencils and surfaces are plane-parallelograms, with one point at the object's position vector; one side lying along the object's X axis with a length set by the X size; and another side starting from the position vector and going "Y size" units in the Y direction and "Z size" units in the X direction. A ground object is an infinte plane perpendicular to the world Z axis. Its Z coordinate sets its height, and the X and Y coordinates are only relevant to the position of the "hot point" used in selecting the object in the editor. Custom objects have points, edges and triangles associated with them. The size fields are relevant only for drawing the object axes in the editor. Shape number 3 is used internally for triangles of custom objects, and should never appear in a data file. POSI - size 12 VECTOR Position; ; the object's position. 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. AXIS - size 36 VECTOR XAxis; VECTOR YAxis; VECTOR ZAxis; These are direction vectors for the object coordinate system. They must be "orthogonal unit vectors" - i.e. the sum of the squares of the vevtor components must equal one (or close to it), and the vectors must be perpendicular. SIZE - size 12 VECTOR Size; See SHAP chunk above. The sizes are used in a variety of ways depending on the object shape. For custom objects, they are the lengths of the coordinate axes drawn in the editor. If the object has its "Quickdraw" flag set, the axes lengths are also used to set the size of a rectangular solid that is drawn rather than drawing all the points and edges. PNTS - size 2 + 12 * point count UWORD PCount; ; point count VECTOR Points; ; points This chunk has all the points for custom objects. The are refered to by thier position in the array. EDGE - size 4 + 4 * edge cout UWORD ECount; ; edge count UWORD Edges; ; edges This chunk contins the edge list for custom objects. The Edges array is pairs of point numbers that are connected by the edges. Edges are refered to by thier position in the Edges array. FACE - size 2 + 6 * face count UWORD TCount; ; face count UWORD Connects; ; faces This chunk contains the triangle (face) list for custom objects. The Connects array is triples of edge numbers that are connected by triangles. PTHD - size 2 + 6 * axis count - Imagine only UWORD ACount; ; axis count TFORM PData; ; axis data This chunk contains the axis data for Imagine "path" objects. The PData array contains a TFORM structure for each point along the path. The "Y size" item for the last point on the path tells whether the path is closed or not. Zero means closed, non-zero means open. Otherwise the Y size field is the distance along the path to the next path point/axis. COLR - size 4 REFL - size 4 TRAN - size 4 SPC1 - size 4 - Imagine only BYTE pad; ; pad byte - must be zero COLOR col; ; RGB color These are the main object RGB color, and reflection, transmission and specularity coefficients. CLST - size 2 + 3 * count RLST - size 2 + 3 * count TLST - size 2 + 3 * count UWORD count; ; count of colors COLOR colors; ; colors These are the color, reflection and transmission coefficients for each face in custom objects. The count should match the face count in the FACE chunk. The ordering corresponds to the face order. TPAR - size 64 - not written by Imagine - see TXT1 below FRACT Params; ; texture parameters This is the list of parameters for texture modules when texture mapping is used. TXT1 - variable size - Imagine only This chunk contains texture data when texture mapping is used. UWORD Flags; ; texture flags: ; 1 - TXTR_CHILDREN - apply to child objs TFORM TForm; ; local coordinates of texture axes. FRACT Params; ; texture parameters UBYTE PFlags; ; parameter flags (currently unused) UBYTE Length; ; length of texture file name UBYTE Name[Length]; ; texture file name (not NULL terminated) UBYTE pad; ; (if necessary to make an even length) BRS1 - variable size - Imagine only (version 1.0) BRS2 - variable size - Imagine only (version 1.1) UWORD Flags; ; brush type: ; 0 - Color ; 1 - Reflection ; 2 - Filter ; 3 - Altitude UWORD WFlags; ; brush wrapping flags: ; 1 WRAP_X - wrap type ; 2 WRAP_Z - wrap type ; 4 WRAP_CHILDREN - apply to children ; 8 WRAP_REPEAT - repeating brush ; 16 WRAP_FLIP - flip with repeats TFORM TForm; ; local coordinates of brush axes. (UWORD FullScale;) ; full scale value (UWORD MaxSeq;) ; highest number for sequenced brushes UBYTE Length; ; length of brush file name UBYTE Name[Length]; ; brush file name (not NULL terminated) UBYTE pad; ; (if necessary to make an even length) The FullScale and MaxSeq items are in BRS2 chunks only. SURF - size 5 - not written by Imagine BYTE SProps; ; object properties This chunk contains object (surface) properties used by Turbo Silver. SProps - PRP_SURFACE ; surface type ; 0 - normal ; 4 - genlock ; 5 - IFF brush SProps - PRP_BRUSH ; brush number (if IFF mapped) SProps - PRP_WRAP ; IFF brush wrapping type ; 0 - no wrapping ; 1 - wrap X ; 2 - wrap Z ; 3 - wrap X and Z SProps - PRP_STENCIL ; stencil number for stencil objects SProps - PRP_TEXTURE ; texture number if texture mapped MTTR - size 2 - not written by Imagine - see PRP1 chunk. UBYTE Type; ; refraction type (0-4) UBYTE Index; ; custom index of refraction This chunk contains refraction data for transparent or glossy objects. If the refraction type is 4, the object has a "custom" refractive index stored in the Index field. The Index field is 100 * (true index of refraction - 1.00) -- so it must be in the range of 1.00 to 3.55. The refraction types 0-3 specify 0) Air - 1.00, 1) Water - 1.33, 2) Glass - 1.67 or 3) Crystal 2.00. SPEC - size 2 - not written by Imagine - see SPC1 above. UBYTE Specularity; ; range of 0-255 UBYTE Hardness; ; specular exponent (0-31) This chunk contains specular information. The Specularity field is the amount of specular reflection -- 0 is none, 255 is fully specular. The "specular exponent" controls the "tightness" of the specular spots. A value of zero gives broad specular spots and a value of 31 gives smaller spots. PRP0 - size 6 - not written by Imagine UBYTE Props; ; more object properties This chunk contains object properties that programs other than Turbo Silver might support. Props - PRP_BLEND ; blending factor (0-255) Props - PRP_SMOOTH ; roughness factor Props - PRP_SHADE ; shading on/off flag Props - PRP_PHONG ; phong shading on/off flag Props - PRP_GLOSSY ; glossy on/off flag Props - PRP_QUICK ; Quickdraw on/off flag The blending factor controls the amount of dithering used on the object - 255 is fully dithered. The roughness factor controls how rough the object should appear - 0 is smooth, 255 is max roughness. The shading flag is interpreted differently depending on whether the object is a light source or not. For light sources, it sets the light to cast shadows or not. For normal objects, if the flag is set, the object is always considered as fully lit - i.e., it's color is read directly from the object (or IFF brush), and is not affected by light sources. The phong shading is on by default - a non-zero value turns it off. The glossy flag sets the object to be glossy or not. If the object is glossy, the "transmit" colors and the index of refraction control the amount of "sheen". The glossy feature is meant to simulate something like a wax coating on the object with the specified index of refraction. The trasmission coefficients control how much light from the object makes it through the wax coating. The Quickdraw flag, if set, tells the editor not to draw all the points and edges for the object, but to draw a rectanglular solid centered at the object position, and with sizes detemined by the axis lengths. PRP1 - size 8 - Imagine only UBYTE IProps; ; more object properties This chunk contains object properties that programs other than Imagine might support. IProps - IPRP_DITHER ; blending factor (0-255) IProps - IPRP_HARD ; hardness factor (0-255) IProps - IPRP_ROUGH ; roughness factor (0-255) IProps - IPRP_SHINY ; shinyness factor (0-255) IProps - IPRP_INDEX ; index of refraction IProps - IPRP_QUICK ; flag - Quickdraw on/off IProps - IPRP_PHONG ; flag - Phong shading on/off IProps - IPRP_GENLOCK ; flag - Genlock on/off The blending factor controls the amount of dithering used on the object - 255 is fully dithered. The hardness factor controls how tight the specular spot should be - 0 is a big soft spot, 255 is a tight hot spot The roughness factor controls how rough the object should appear - 0 is smooth, 255 is max roughness. The shiny factor in interaction with the object's filter values controls how shiny the object appears. Setting it to anything but zero forces the object to be non-transparent since then the filter values are used in the shiny (reflection) calculations. A value of 255 means maximum shinyness. INTS - size 4 - not written by Imagine FRACT Intensity; ; light intensity This is the intensity field for light source objects. an intensity of 255 for a sun-like light fully lights object surfaces which are perpendicular to the direction to the light source. For lamp-like light sources, the necessary intensity will depend on the distance to the light. INT1 - size 12 - Imagine only VECTOR Intensity; ; light intensity This is like INTS above, but has seperate R, G & B intensities. STRY - size 56 - not written by Imagine STORY story; ; a story structure for the object. The story structure is described above. ANID - size 64 - Imagine only LONG Cellno; ; cell number TFORM TForm; ; object position/axes/size in that cell. For Imagine's "Cycle" objects, within EACH DESC chunk in the file - that is, for each object of the group, there will be a series of ANID chunks. The cell number sequences of each part of the must agree with the sequence for the head object, and the first cell number must be zero. FORD - size 56 + 12 * PC - Imagine only WORD NumC; ; number of cross section points WORD NumF; ; number of slices WORD Flags; ; orientation flag WORD pad; ; reserved MATRIX TForm; ; object rotation/scaling transformation VECTOR Shift; ; object translation VECTOR Points[PC]; ; "Forms" editor points For Imagine's "Forms" objects, the "PNTS" chunk above is not written out, but this structure is written instead. The point count is PC = NumC + 4 * NumF. The object's real points are then calculated from these using a proprietary algorithm. The tranformation parameters above allow the axes of the real object be moved around relative to the "Forms" points.
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