Quake2Wrack

This little tool converts Quake's .bsp to Wrack's .map format. The converter includes geometry, entity and texture conversion. Entity and texture references can be found in two seperate text files. So far I've only done Quake's shareware textures, you'll have to add licensed and custom textures yourself.

This looks awfully familiar.

Technical Details

The first step is to dissect Quake's level format. Thankfully this format was published centuries ago and can be found here. The converter will break down every vertex, brush, and entity. Now we have a collection of data we'd like to convert to Wrack's level format.

Wrack's level format had to be reverse engineered. It's not completely documented yet, but below is a table of all the relevant data required for the converter. Keep note that Wrack strings use a 2-byte prefix indicating its length and is then followed by that number of characters.

wrack_header_t
uint32_t	magic_number	MMAP
uint32_t	map_version	25
wrack_string_t	map_name
wrack_string_t	storyboard_name
wrack_string_t	skybox_name
wrack_string_t	next_map_name
uint16_t	par_time
uint32_t	par_score
uint16_t	quickplay_order
wrack_string_t	author_name
wrack_string_t	music_file_name
wrack_string_t	boss_music_file_name
wrack_string_t	ambient_sound_file_name
float	ambient_sound_volume
boolean	is_fog_enabled
uint32_t	rgba_fog_colour	Alpha is unused
float	fog_start
float	fog_end
uint32_t	map_flags
uint32_t	vertex_count
uint32_t	face_count
uint32_t	zone_count
uint32_t	ground_count
uint32_t	thing_count

Next up is all the vertex data. Wrack vertices are all stored sequentially as 22-byte structs. The number of vertices stored is based on the vertex count variable found in the header, so you're gonna have to iterate through these.

wrack_vertex_t
int16_t	x
int16_t	y
int16_t	z
float	texture_coord_u
float	texture_coord_v
float	lightmap_coord_u
float	lightmap_coord_u

After vertices comes the face data. A Wrack face is a collection of vertices that form a polygon. Just like vertices, these are stored sequentially and must be iterated through.

wrack_face_t
uint32_t	vertex_count
uint32_t*	vertex_index	One index for every vertex
uint32_t	face_flags
wrack_string_t	texture_file_name
float	texture_rotation
float	texture_x_scale
float	texture_y_scale
float	texture_x_offset
float	texture_y_offset
boolean	is_texture_x_flipped
boolean	is_texture_y_flipped
uint8_t	texture_plane_type
uint8_t	light
uint32_t	rgba_light_colour
float	friction
uint32_t	unknown_1	Unknown
wrack_string_t	action
uint8_t	activation_type
uint8_t	activated_by
uint8_t	tag
uint8_t	unknown_2	Unknown
wrack_string_t	argument_1
wrack_string_t	argument_2
wrack_string_t	argument_3
wrack_string_t	argument_4
wrack_string_t	argument_5
uint32_t	fx_flags
uint32_t	rgba_fog_colour	Actually saved as BGRA
float	fx_start
float	fx_end

Whew, that was a big one. Up next are non-geometry data collections. The converter currently does nothing with these and just writes 20 empty bytes, so it's up to you whether to use it or not.

wrack_zone_t
uint32_t	face_count
uint32_t*	face_index	One index for every face
uint16_t	type
uint16_t	tag

And the other one.

wrack_group_t
uint32_t	face_count
uint32_t*	face_index	One index for every face

Now back to some more interesting data: things. In the Wrack universe a thing is an entity in the world, like a monster or weapon. Just like vertices, faces, zones and groups, these must are stored sequentially.

wrack_thing_t
wrack_string_t	name
wrack_string_t	data	Unknown behaviour

As you can see the serialisable data string for things hasn't been figured out yet. It's best to just keep it empty since Wrack is sufficient with the thing name alone. Up next comes a big collection of map scripts, collision data, lightmap information, etc. We'll just let the level editor take care of this, so just write 5 empty bytes to finish it off.

Conclusion

The converter is not perfect. For example, Quake uses more precise coordinates for its vertices, causing some broken vertices and faces in Wrack. Somehow there's also some convex shapes that are allowed in Quake, but not in Wrack. You'll have to fix these faces manually through WrackEd, Wrack's level editor. This tool only converts geometry, entities and textures. Logic behind doors, buttons, spawners, etc. are ignored. It will also only work for Quake .bsp files. Quake II, Half-Life, and other games that use the same format are not supported.

A cool thing you can do is define the entity and texture conversion. By editing EntityList and TextureList you decide what you're converting. You could change all Quake Zombies into Wrack Bazookas if you want to. Below is a download link if you'd like to give it a whirl.

Download Quake2Wrack
Source code

And here are Steam workshop items for Wrack made with Quake2Wrack and its predecessor.

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