OJT Format (Shadowcaster)

Overview

Shadowcaster OJT files describe a list of static objects present in a given level. These files are a linear list of 57-byte records with no header.

uint32_t Tag;              // does not have to necessarily be unique.
uint32_t Ptr_Prev;         // typically if there is a previous OJT record before this one, this is set to sizeof(ojt_record) (57).
uint32_t Ptr_Next;         // same as above, but forwards in the file.
uint8_t  Collision;        // typically zero for a non-solid object, or 1 for a solid one.
uint8_t  Gravity;          // a bitfield describing the object's relationship to gravity.
                           // some known values: 0 = no gravity; 1 = hangs from ceiling; 3 = spawn on ceiling, subject to gravity.
char     DisplayName[20];  // not used by the game. a string that usually contains the name of the sprite used. seems to be an editor leftover?
uint32_t Pic;              // a literal lump number from RAVDATA.DAT. This is the graphic the object will use in the 3D view.
uint32_t Width;            // the object's width (or "radius" if you prefer), represented in frac-units (0-63 within a tile).
uint32_t Height;           // same as the above, but the object's height along Z+.
uint32_t Unknown;
uint8_t  TileX;
uint8_t  TileY;            // the object's coarse tile X/Y coordinates (0-31 are valid).
uint8_t  Sides;            // the number of sides the sprite has. for example: 0 = one-sided sprite, 8 = eight-sided sprite (like Doom).
uint16_t SubTileX;
uint16_t SubTileY;         // the object's sub-tile X/Y fractional values (0-63 are valid).

Reading an OJT file

Adapted from MapCaster GML:

for(i = 0; i < NumOjtsInFile; i++) {
	ojt.Tag = buffer_read(ojt_file, buffer_u32);
	ojt.Ptr_Prev = buffer_read(ojt_file, buffer_u32);
	ojt.Ptr_Next = buffer_read(ojt_file, buffer_u32);
	ojt.Collision = buffer_read(ojt_file, buffer_u8);
	ojt.Gravity = buffer_read(ojt_file, buffer_u8)
	ojt.DisplayName = ReadString(20);
	ojt.Pic = buffer_read(ojt_file, buffer_u32);
	ojt.Width = buffer_read(ojt_file, buffer_u32);
	ojt.Height = buffer_read(ojt_file, buffer_u32);
	ojt.Unknown = buffer_read(ojt_file, buffer_u32);
	ojt.x = buffer_read(ojt_file, buffer_u8) * TILESIZE;  // TILESIZE = 64 in Shadowcaster
	ojt.y = buffer_read(ojt_file, buffer_u8) * TILESIZE;  // TILESIZE = 64 in Shadowcaster
	ojt.Sides = buffer_read(ojt_file, buffer_u8);
	ojt.x += buffer_read(ojt_file, buffer_u16);
	ojt.y += buffer_read(ojt_file, buffer_u16);
}