DriftEngineRenderer · function
billboardMatrixY
Orient a mesh so its +Z faces the camera, writing the model matrix in place.
Explained in Hello world.
function billboardMatrixY(out: mat4, x: number, y: number, z: number, cameraX: number, cameraZ: number, scaleX?: number, scaleY?: number): voidimport { billboardMatrixY } from '@driftengine/core';Parameters
| Parameter | Type | Description |
|---|---|---|
out | mat4 | |
x | number | |
y | number | |
z | number | |
cameraX | number | |
cameraZ | number | |
scaleX? | number | |
scaleY? | number |
In depth
The two variants are a real distinction rather than a convenience pair, and picking the wrong one is the classic billboard mistake:
- Cylindrical (
billboardMatrixY) spins about the world Y axis only. Anything standing on the ground uses this — a figure, a sign, a tree. Look down at it from above and it stays upright, because a thing with feet does not tilt to face you. - Spherical (
billboardMatrix) faces the camera on every axis. For something with no up of its own: a spark, a puff of smoke, a glow.
Allocation-free: the caller owns the matrix and it is overwritten, so a frame drawing a hundred of these allocates nothing.