Dream world interactions

For new model output, use Dream 2. Dream 1 examples below remain supported.

Dream 2 describes where assemblies live and which bounded activities they support. Dream 1 examples below document compatibility. The canonical handmade mock is interactive-world.dream: locomotive, carriage, plane, boat, bicycle, skateboard, station, boathouse, stone passage and a seated traveler and a standing Explorer. Nine placements, five routes, one continuous watercourse. These names select no engine recipes. Features compile to validated scene data.

Routes and placement

dream 1;
material paint = toon #448b87;
object "Shuttle" {
  body solid radius 20 height 24;
  rideable at [0,18,0];
  part deck box paint at [0,10,0] size [40,20,22];
}
route tour path loop speed 35 wait 4 {
  point [400,400]; point [600,400];
  point [600,600]; point [400,600];
}
place shuttle "Shuttle" on tour scale 1;

compileDreamWorld(text) returns {assemblies, routes, objects, waters}. Pass the result through parseScene and validateScenePlayability as the next boundaries. Compiling alone does not prove a route is safe in a particular world. The object-only compileDream rejects world declarations rather than silently discarding them. The original object syntax stays supported.

Route syntax:

route id rail|path|water|air loop|shuttle speed number [altitude number] [wait number] {
  point [x,y];
  // let and bounded repeat work here too
}
place id "Assembly name" on route_id [offset distance] [scale number];
place id "Assembly name" at [x,y] [scale number] [heading degrees];

Brackets in this syntax description indicate optional modifiers; omit them in source. XY uses the scene's canonical top-left coordinates. Local part XYZ still uses Y up. Heading zero faces +X; positive heading turns toward canonical +Y. Route positions use a shared piecewise-linear centerline with a smoothed heading estimate at corners. Rails, sleepers, route paths and moving vehicles share it. Author enough points for the intended curvature; a tight corner is not a physical steering simulation. offset follows distance along the path, including corners, so carriages keep their spacing during a loop's dwell.

For autonomous actors without a control profile, every leg waits at its starting stop, then travels at fixed speed. Loops wrap; shuttles reverse at endpoints. Wheels use an unwrapped distance clock, avoiding a roll-phase jump when a loop wraps. All poses derive from the fixed simulation clock; pause freezes them, a race restart restarts them, and returning only the car to spawn preserves the world clock.

Water actors float at the authored level minus two units and leave persistent surface wakes. The whole physical footprint must stay in navigable water. Water routes require enough clearance for the full body beneath a bridge deck. Boats use the terrain bed independently of the ground driving height. Air actors have a bounded 180-unit takeoff/landing ramp at the route endpoints, then cruise at their declared height above local ground. They return to a ground boarding stop. These are authored vehicle activities, not free-flight aerodynamics, buoyancy volumes, traffic AI or general rigid-body physics.

Boarding

Inside an object:

rideable at [0,18,0];

This legacy declaration is a passenger seat on an autonomous route. Dream 2 adds direct controls:

rideable(at=[0,18,0],control=bicycle);

Profiles are car, bicycle, skateboard, scooter, boat and plane. Vehicles with a profile start parked. The route supplies initial placement and infrastructure, not their movement. F leaves the current vehicle, preferring dry ground and allowing water when the walking body fits. WASD then walks or swims; F enters a nearby seat within 60 units of its body's edge and 28 units of elevation. You control the new vehicle, and it stays where you park it. The original car stays parked too. R returns to that car's starting point while retaining parked vehicles and damage; Start over restores the world.

Walking and swimming follow screen directions after camera rotation. Shift runs or swims faster. Space jumps on foot, bicycles, skateboards and scooters, or hops a boat. Low contact steps are walkable with headroom. W/S accelerates, brakes and reverses ground vehicles and boats; A/D steers. Bicycles lean and widen their turning radius at speed; boats retain momentum through rudder turns. Aircraft need speed before Space can climb; Shift descends, and low airspeed causes descent. F cannot eject you in flight. Boats use full-hull clearance against water banks and bridge decks. Ground vehicles still have one driving height per XY; boats and swimmers separately use water support and finite deck/rail headroom.

Destination ground parking uses furnish(...,role=controllable) or place(...,role=controllable,parked=true). Unoccupied poses stay instanced and saved; one occupied fleet rig stays within the existing live-assembly cap. Boats and planes retain their resident support path.

The seated traveler and standing Explorer are Dream assemblies. Smaller vehicles and walking get closer camera framing. Checkpoints advance only in the original racing car; other modes preserve progress. Unconfigured train seats remain autonomous passenger rides. Pause freezes controls, routes, waves and destruction. The current guide and runnable bicycle describe the complete control contract.

Buildings, doors and passages

An upright solid may replace its default cylinder with 1–8 authored cylinders:

contact at [0,0,-24] radius 8 height 48;
contact at [0,0,24] radius 8 height 48;
contact at [0,48,0] radius 32 height 12;

The tuple is object-local XYZ; Y is the bottom of that cylinder. Radius is 1–64, height 1–160; X/Z offsets remain ±64 and bottom Y is 0–128. Appearance stays independent. These are intentional wall/roof volumes, not noisy outline decomposition or a second physics engine. The broad-phase radius is computed from their extents. Cylinder contacts remain vertical. The controlled player keeps its existing driving cylinder; compound contacts, rideable seats and steam emitters currently belong on world objects only.

Grounded cars may pass beneath a roof with adequate headroom. Side walls block, ascending cars hit the roof underside, and descending cars can land on top. Road clearance validation uses the same contact intervals. Existing objects without contact keep their original full-cylinder behavior. Compound contacts require upright solids and are not allowed on route actors in this slice.

A door uses a proximity-driven joint:

joint door at [36,2,-13] open y (105,100) {
  part panel box paint at [0,18,12] size [3,36,24];
}

Arguments are opening angle in degrees and trigger radius in local units. The engine eases the pose across the inner 24 units of the range and restores the rest pose on departure. It still opens with reduced motion enabled. A joint chooses either swing oscillation or open proximity motion. The doorway's authored wall contacts leave a real opening. Door panels are visual; they do not push cars with a rotating collision mesh.

The stone passage is a freestanding covered tunnel on the rail loop. It has walls, headroom and a collidable roof. It does not excavate the existing heightfield or add underground caves. True terrain tunnels and stacked terrain layers need a separate ground representation; the current terrain still has one height per XY.

Continuous watercourses

watercourse river level 0 depth 8 bank 32 color #237e8c flow [0,24] {
  point [1930,1050,320];
  point [1970,1260,140];
  point [1980,1480,150];
  point [1920,1740,150];
  point [1830,2010,420];
}

Each station is [x,y,width]. The compiler creates one simple polygon with rounded caps, preserving a continuous basin between widened source/outlet pools. There are no overlapping independent water tiles or internal river seams. The existing terrain carving, shoreline, driving current and wave renderer consume the same polygon. Degenerate, crossing, off-world or oversized basins fail. Depth, bank, level and current retain the existing landscape bounds. This syntax uses wave speed 70, damping 1.4, strength 1.2 and water drag 2.2 per second; the underlying JSON landscape contract still exposes the full bounded parameters.

Steam and budgets

emit steam at [23,51,0] rate 6;

One engine-owned emitter per assembly, 1–12 particles per second, bounded local position. Train and station examples use it. Steam follows a moving emitter's heading, rises and dissipates. It shares the existing 256-particle pool and one particle draw with car effects; far emitters are culled and reduced motion clears it. Model-authored particle/shader programs never execute.

Limits: 12 routes, 2–64 points per route (loops need ≥3), route length ≤12,000, vehicle speed 12–160 (ambient .5–160), stop wait 0–12 seconds, air altitude 60–300, trailing offset 0–2,048. World source declares at most 64 placements and 8 watercourses. A watercourse has 2–8 stations of width 80–1200 and compiles into the unchanged bounded water schema. Scenes accept at most 24 mobile actors, including controllable vehicles, 16 emitters and 24 jointed live assemblies including the player. Existing source/token/work, part and joint limits remain.

Static scenery remains instanced. Route infrastructure uses shared surfaces and instanced rails/sleepers. Vehicle bodies merge by material; matching wheel pieces merge around retained pivots. Active vehicle collision uses bounded cylinders against the car. Routes are validated against static geometry and water; they do not dynamically negotiate with other vehicles or knocked props. Mock layout keeps independent routes apart. Geometry, motion and collision checks remain separate from any future Muse provider evaluation.

Ambient wildlife in Dream 2

Use route(kind=ambient,...) with a decor assembly to move wildlife without roads, rails, runways or grass clearing. Optional altitude 60–300 stays constant above terrain through the loop seam; omit altitude for dry ground movement. Ambient actors create no physical contacts. Existing route, actor and animation caps still apply. This is bounded authored movement, without perception or avoidance. See the complete bird example and reference.