[generator] — for lsystem

Key	Type	Notes
axiom	string	Starting string. Required, non-empty.
rules	table k = "v"	Each key a single character (the predecessor). Required.
angle_deg	number	Turn angle for +/-. Default 25.
max_depth	integer	Iterations to precompute; clamped to 1..=7. Default 4. Inert under growth = "endless".
turtle	flat / space	Which turtle walks the string. Default flat, the plane walk. space walks in depth, seen through the camera block. An unknown name is a load error naming both.
growth	fixed / endless	Default fixed: one cached depth, picked by visible_depth. endless grows a vine that never ends, at the rate grow sets. An unknown name is a load error naming both.
trail	integer	Endless only: how many segments the vine keeps behind its tip. Default 2000. Held to the tier’s cap (seg3d_segments in space, max_segments in flat), and the clamp is announced. A grammar whose whole stream is shorter than trail is a load error.
follow_window	integer	Endless only: how many of the newest segments the view follows the centre of. Default 32. Wider smooths the jump a ] makes.
seed	integer or "random"	The salt for hash()/noise() — see Seeded randomness. Not an L-system key: the expansion is deterministic and ignores it, and any system’s preset may declare one. Default 0.

Turtle vocabulary in the expanded string: F/G draw forward, f moves without drawing, +/- turn by angle_deg, [/] push/pop the branch state, any other character is an inert grammar variable.

Under turtle = "space" the turtle carries a heading, a left and an up direction, and five more symbols turn it, each by angle_deg: &/^ pitch down and up, \// roll, and | turns it around. +/- still turn it left and right. Under flat those five stay inert variables, so a grammar that names them as variables walks what it always did. The space figure is drawn through the camera block (yaw, pitch, distance, fov, focus, aperture, fog, solid), and thickness is in pixels at the focal plane. A segment is a straight stroke with no join, so a sharp turn shows a facet at any width above a hairline.

Under growth = "endless" nothing is cached. The turtle walks the grammar’s derivation one symbol at a time at a fixed internal depth, grow draw steps a second, and keeps the newest trail segments; the oldest tail fraction of them fades out. The view follows the centre of the newest follow_window segments on a spring with time constant follow. In space the camera orbits that point; in flat the figure pans by it, on top of pan_x/pan_y. The walk is depth-first, so a ] sends the tip back to its branch point: vines and short-branched coral suit endless, and a deep tree, whose ] jumps a long way back, does not.

What each mode makes inert is in the generated table under System: lsystem: rotation, scale, stroke_blend, mirror_order and mirror_reflect are flat-only; the camera block is space-only; visible_depth, draw_progress and the mirror pair are inert under endless, and grow, tail and follow under fixed.