Physics · interface

SurfaceHit

Explained in Your first game, Rigid bodies.

interface SurfaceHit

import type { SurfaceHit } from '@driftengine/physics';

Properties

Name	Type	Description
`y`	`number`	Height of the surface in the queried column.
`normalX`	`number`
`normalY`	`number`
`normalZ`	`number`
`tangentX`	`number`	Direction of travel at the nearest point on the centreline.
`tangentY`	`number`
`tangentZ`	`number`
`distanceM`	`number`	Arc length of that nearest point. How far along the route you are.
`lateralM`	`number`	Signed offset from the centreline, positive to the character's right.
`halfWidthM`	`number`	Half the surface's width here — how much room is left before the edge.
`bankRad`	`number`
`tiltX`	`number`	Which way up looks here — the ruled surface's own normal, not the cross-section's. More A separate field because it answers a separate question. `normal` is the ground a character stands on and every movement rule is tuned against it: how steep is this to walk, which way does gravity pull along it, is it floor or is it wall. That question is about the cross-section, and its answer is the same all the way across the deck. This one is about how the surface looks where you are standing on it, and on a deck whose bank rolls it is a very different number: the ruled surface climbs far more steeply along the route near its edges than the centreline does — 57° measured on one chicane against the centreline's 11°, and past vertical on a chute. Correct geometry, and correct for orienting a body that has to look like it is on the deck. Fed to the walking rules instead it takes the ground away: a character met a chicane's edge as a wall and fell down it at 20 m/s a hand's width above the deck, never landing, which is exactly what flying looks like.
`tiltY`	`number`
`tiltZ`	`number`