FUN GAME SAVE FILE FORMAT VERSION 0.3
	- little endian
	- 32-bit IEEE-754 floats
	- UTF-8 strings which are *not* null terminated
	- units are metric and 1 unit is 1 meter
	- quaternions are xyzw and need normalization
	- pids start at 1 and are monotonic, 0 is reserved for null parent

VERSION CHANGES
	0.3:
		Added root_body to identify which body drives the entity pose.
		Stored after body_cnt; adds 4 bytes per physics component.
		Zero-based body index. Empty rigs store 0.

	0.2:
		Replaced axis_a/axis_b with frame_rot_a/frame_rot_b.
		Joint records increased from 85 to 93 bytes.

CHUNK LABELS
	- ENVR
	- ENTT
	- TRFM
	- MODL
	- MTEX
	- MSHD
	- PHYS

DATA RECORDS
	- environment record
	- entity record
	- transform component record
	- model component record
	- texture override record
	- shader override record
	- physics component record
		- physics body record
		- physics shape record
			- box
			- sphere
			- cylinder
			- capsule
			- convex hull
			- static trimesh
		- physics joint record

FILE HEADER
	char[4] magic "FGSF"
	u16 major
	u16 minor

CHUNK
	char[4] label
	u32 size
	u8[size] data

ENVR
	f32 day_start
	f32 day_len

ENTT
	u64 next_pid
	u32 entity_cnt

	repeat entity_cnt:
		u64 pid
		u32 name_len
		char[name_len] name

TRFM
	u32 transform_cnt

	repeat transform_cnt:
		u64 pid
		u64 parent_pid
		f32[3] pos
		f32[4] rot
		f32[3] scale

MODL
	u32 model_cnt

	repeat model_cnt:
		u64 entity_pid
		u32 key_len
		char[key_len] key
		bool(u8) draw

MTEX
	u32 texture_override_cnt

	repeat texture_override_cnt:
		u64 entity_pid
		u32 material_idx
		u32 key_len
		char[key_len] texture_key

MSHD
	u32 shader_override_cnt

	repeat shader_override_cnt:
		u64 entity_pid
		u32 material_idx
		u32 key_len
		char[key_len] shader_key

PHYS
	u32 physics_cnt

	repeat physics_cnt:
		u64 pid
		u32 body_cnt
		u32 root_body
			body[body_cnt]
		u32 joint_cnt
			joint[joint_cnt]

PHYSICS BODY
	f32[3] pos
	f32[4] rot
	f32 linear_damping
	f32 angular_damping
	f32 gravity_scale
	u8 physics_mode
	bool(u8) enable_sleep
	u32 shape_cnt
		shape[shape_cnt]

PHYSICS SHAPE
	u8 tag
	f32[3] pos
	f32[4] rot
	f32 density
	f32 friction
	f32 restitution
	u32 category_bits
	u32 mask_bits

	switch tag:
		BOX
		f32[3] sz

		SPHERE
		f32 radius

		CYLINDER or CAPSULE
		f32 height
		f32 radius

		CONVEX HULL
		u32 points_cnt
		f32[points_cnt][3] points

		TRIMESH
		u32 point_cnt
		u32 index_cnt
		f32[point_cnt][3] points
		u32[index_cnt] indices

PHYSICS JOINT
	u8 tag
	u32 body_a
	u32 body_b
	u32 flags
	f32[3] anchor_a
	f32[3] anchor_b
	f32[4] axis_a
	f32[4] axis_b
	f32 lower
	f32 upper
	f32 spring_hz
	f32 spring_damping
	f32 motor_speed
	f32 motor_force