source: trunk/src/testing/app/bitplay/libimg/softpic.h @ 4

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/*
 * SoftImage picture file format (.pic).
 * Transcribed from their printed documentation.
 *
 * Ratio: is the aspect ratio of pixels for this image.
 *  This aspect is the ratio X/Y (if a pixel is 2x wider than tall,
 *   the ratio is 2.0).  For displaying images on output devices
 *   with aspect ratio different from 1.0.
 *
 * N.B. The pixel ratio is computed according to Full Frame.
 *
 * Fields: which scan-lines are present in the picture file.
 * For normal images this will be Full-frame (3), but if you use video
 * output you will probably want to double the time sampling and compute
 * only fields (every alternate scan line).
 * The field containing the top scan-line is the ODD one (1), the other
 * is EVEN (2).  The field sequence for NTSC is E-O-E-O...,
 * while for PAL O-E-O-E...
 *
 * Chained: this flag indicates the presence of other packets, generally
 * it is 1 except for the last packet where it's 0.
 *
 * Encoding part: all encoding data are coded byte-by-byte (with some
 * exceptions) so when we code raw information, we have each byte following
 * each other.  For example, here is a 512x512 RGBA picture:
 *
 * <FILE-CHUNK>
 *  id = 0x5380f643
 *  vers = 1.2 (only informatiive info)
 *  comment = 'none'
 *
 * <PICT-CHUNK>
 *  id='PICT'
 *  width=512
 *  height=512
 *  ratio=1.0
 *  fields=3 (full-frame)
 *  padding=(unused)
 *
 * <PACK-CHUNK>
 *  chained=1
 *  nb bits=8
 *  type=0
 *  fields=224 (red+green+blue)
 *
 * <PACK-CHUNK>
 *  chained=0
 *  nb bits=8
 *  type=0
 *  fields=16 (alpha)
 *
 * <SCAN-LINE 1>
 *  R,G,B,... (3x512 bytes)
 *  A,A,A,... (512 bytes)
 *
 * <SCAN-LINE 2>
 *  R,G,B,...
 *  A,...
 * ...
 *
 */

/*
 * All binary files have a similar header:
 */

struct softhdr {
        unsigned long id;       /* SoftImage magic number */
#define SOFT_MAGIC  0x5380f634

        float   version;        /* Version of system that produced it */
        char    comment[80];    /* user-definable comment */
};

/*
 * Then follows the specific chunk for the type of file (here .pic):
 */

struct softpict {
        unsigned long   id;     /* 'PICT' */
#define SPICT_MAGIC     0x50494354

        short   width, height;  /* in pixels */
        float   ratio;          /* Pixel ratio (X/Y) */
        short   fields;         /* 1=odd, 2=even, 3=full-frame */
        short   padding;        /* (to pad this struct to 4-byte multiple) */
};

/*
 * Now the associated data.
 * For a picture file we find first a list of descriptor packets.
 * A packet describes how the different fields of an image are coded, i.e.
 * which fields are coded together, the type of data (integer, float &c)
 * and the compression technique.
 */

struct softpack {               /* Pack chunk */
        unsigned char chained;  /* another pack chunk follows this one */
        unsigned char nbits;    /* bits per data value (8?) */
        unsigned char type;     /* bit-field describing data format: */
#define SPICT_UINT      0x00    /* unsigned int */
#define SPICT_SINT      0x10    /* signed int */
#define SPICT_FLOAT     0x20    /* float */
#define SPICT_NOCOMP    0x00    /* uncompressed */
#define SPICT_PURERLE   0x01    /* "pure" run-length encoded */
#define SPICT_MIXEDRLE  0x02    /* "mixed" run-length encoded */

        unsigned char fields;   /* bit-field describing what data are present */
#define SPICT_R         0x80    /*  red */
#define SPICT_G         0x40    /*  green */
#define SPICT_B         0x20    /*  blue */
#define SPICT_A         0x10    /*  alpha */
#define SPICT_SHADOW    0x08    /*  shadow */
#define SPICT_DEPTH     0x04    /*  depth */
#define SPICT_AUX1      0x02    /*  auxiliary 1 */
#define SPICT_AUX2      0x01    /*  auxiliary 2 */

};