Comments

The resource A has a limit of X because it is referenced by JKL with data type T, using [Remark]
The resource clipnodes has a limit of 32768 because it is referenced by other clipnodes with data type short, using positive values > 0

• This version of the map format is colloquially known as Valve20 to differentiate from the original Quake version
• Valve20 is now the de-facto map format all Quake-based and Quake-derived editors and compilers support due to the precision in texture alignment
• TrenchBroom uses the OS's clipboard for copy and paste (not the case with JACK/VHE3.x) and uses the map format to represent brush & entity data to be pasted. It also means clipboard-based IPC can be done using the map format.

• func_detail does not reduce world leaves
• func_detail instead reduce VIS portals generated by HLBSP. if without it HLBSP makes VIS portals around detail geometry, with it it just treat the surrounding area as a single VIS leaf
• func_detail is gone at the end of HLBSP, and is world geometry after that point
• hence HLRAD cannot treat it in any way other than opaque world brush because it's gone by the time it's run

• wheels distance is only measured forward from origin. To make the train travel as much on the path as possible, the origin needs to be located at the center of the back axle.
• wheel distance defaults to 100.
• target of a path_track is fired when the origin passes the path_track.
• the position and angle is set wrt the origin point as follows:
  1. trace a line forward.
  2. if there's enough distance to the end of the current path, keep heading
  3. if wheel distance > distance to next path, subtract current distance to next path, then iterate the path forwards until the distance fits the path. the point where distance is 0 is the new heading.
  4. origin moves forward
  5. angle is adjusted to point to the heading. this will in all cases be shorter than wheel distance; the sharper the curve the more noticeable. this also means the front wheel part will always overshoot the path. but the origin is guaranteed to always be on the path.

textures can be scaled as need because now lightmap can be recalculated after any changes.

typedef struct {
    char[4] magic;                      // File format magic number, "JHMF" in ASCII encoding
    int32 version;                      // File format version (currrently 122)
    int32 ep_count;                     // Number of recent export paths
    p_char[ep_count] export_paths;      // Recent export paths
    bg_image[3] bg_images;              // Background images
    int32 group_count;                  // Number of groups in the map
    Group[group_count] groups;          // Group objects
    int32 visgroup_count;               // Number of VisGroups
    VisGroup[visgroup_count] visgroups; // VisGroups objects
    Vector cordon_min;                  // Minimum corner of the Cordon box
    Vector cordon_max;                  // Maximum corner of the Cordon box
    int32 camera_count;                 // Number of Camera objects
    Camera[camera_count] cameras;       // Camera objects
    int32 path_count;                   // Number of path objects
    Path[path_count] paths;             // Path objects (created with the Path tool)
    Entity[] entities;                  // All entities including worldspawn, read until the end of the file
} Jmf;

typedef struct {
    p_char path;                        // Background image path
    double scale;                       // Image scale
    int32 luminance;                    // Image brightness (0-255)
    int32 filtering;                    // Image filtering (0=nearest, 1=linear)
    int32 invert;                       // Invert image colours
    int32 offset_x;                     // Image horizontal offset from center
    int32 offset_y;                     // Image vertical offset from center
    byte[4] unknown;
} bg_image