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UsingCameraSystem.md

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id camerasystem
title Camera System
sidebar_position 10

Using the Camera System

This document explains how to move, rotate, and control cameras using the APIs in CameraSystem.swift.

Get the Game Camera

For gameplay, always use the game camera (not the editor/scene camera). Call findGameCamera() and make it active:

let camera = findGameCamera()
CameraSystem.shared.activeCamera = camera

If no game camera exists, findGameCamera() creates one and sets it up with default values.

Translate (Move) the Camera

Use absolute or relative movement:

// Absolute position
moveCameraTo(entityId: camera, 0.0, 3.0, 7.0)

// Relative movement in camera local space
cameraMoveBy(entityId: camera, delta: simd_float3(0.0, 0.0, -1.0), space: .local)

// Relative movement in world space
cameraMoveBy(entityId: camera, delta: simd_float3(1.0, 0.0, 0.0), space: .world)

Rotate the Camera

Use rotateCamera for pitch/yaw rotation, or cameraLookAt to aim at a target.

// Rotate by pitch/yaw (radians), with optional sensitivity
rotateCamera(entityId: camera, pitch: 0.02, yaw: 0.01, sensitivity: 1.0)

// Look-at orientation
cameraLookAt(
    entityId: camera,
    eye: simd_float3(0.0, 3.0, 7.0),
    target: simd_float3(0.0, 0.0, 0.0),
    up: simd_float3(0.0, 1.0, 0.0)
)

Camera Follow

Follow a target entity with a fixed offset. You can optionally smooth the motion.

let target = findEntity(name: "player") ?? createEntity()
let offset = simd_float3(0.0, 2.0, 6.0)

// Instant follow
cameraFollow(entityId: camera, targetEntity: target, offset: offset)

// Smoothed follow
cameraFollow(entityId: camera, targetEntity: target, offset: offset, smoothFactor: 6.0, deltaTime: deltaTime)

Dead-Zone Follow

cameraFollowDeadZone only moves the camera when the target leaves a box around it. This is useful for platformers and shoulder cameras.

let deadZone = simd_float3(1.0, 0.5, 1.0)
cameraFollowDeadZone(
    entityId: camera,
    targetEntity: target,
    offset: offset,
    deadZoneExtents: deadZone,
    smoothFactor: 6.0,
    deltaTime: deltaTime
)

Camera Path Following

The camera path system moves the active camera through a sequence of waypoints with smooth interpolation.

Start a Path

let waypoints = [
    CameraWaypoint(
        position: simd_float3(0, 5, 10),
        rotation: simd_quatf(angle: 0, axis: simd_float3(0, 1, 0)),
        segmentDuration: 2.0
    ),
    CameraWaypoint(
        position: simd_float3(10, 5, 10),
        rotation: simd_quatf(angle: Float.pi / 4, axis: simd_float3(0, 1, 0)),
        segmentDuration: 2.0
    )
]

startCameraPath(waypoints: waypoints, mode: .once)

You can also build waypoints that look at a target:

let waypoint = CameraWaypoint(
    position: simd_float3(0, 5, 10),
    lookAt: simd_float3(0, 0, 0),
    up: simd_float3(0, 1, 0),
    segmentDuration: 2.0
)

Update Every Frame

Call updateCameraPath(deltaTime:) from your main update loop:

func update(deltaTime: Float) {
    updateCameraPath(deltaTime: deltaTime)
}

Looping and Completion

startCameraPath(waypoints: waypoints, mode: .loop)

let settings = CameraPathSettings(startImmediately: true) {
    print("Camera path completed")
}
startCameraPath(waypoints: waypoints, mode: .once, settings: settings)

Notes

  • startCameraPath and updateCameraPath operate on CameraSystem.shared.activeCamera.
  • segmentDuration is the time to move from the current waypoint to the next.
  • For gameplay, always acquire the camera with findGameCamera() and set it active before path playback or follow logic.