/camera-systems

Follow & framing — depth for camera-systems

Detail the camera-systems body defers here: the smoothing math, a full 2D rig, 3D orbit/first- person specifics, multi-target framing, cinematic blends, and the per-engine rig mapping. Snippets target Godot 4.7 and Unity 6.3 LTS / Cinemachine 3.

1. Why 1 - exp(-rate*dt) (frame-rate-independent smoothing)

A naive pos = lerp(pos, target, k) applies k per frame, so at 144 FPS it smooths far more per second than at 30 FPS — the feel changes with hardware. Exponential smoothing fixes the rate per second:

t = 1 - exp(-rate * dt)      # rate ≈ 5 (floaty) .. 12 (snappy)
pos = lerp(pos, target, t)   # identical convergence at any frame rate

A critically-damped spring (Unity Vector3.SmoothDamp, or a hand-rolled spring with smoothTime) gives the same frame-rate independence plus velocity continuity (no overshoot). Prefer the engine's built-in spring/smoothing before hand-rolling.

2. Full 2D rig: deadzone + look-ahead + bounds

Order of operations each frame, after the target moves:

1. Compute target overflow beyond the deadzone (box or circle) → move the focus by the overflow only.
2. Add look-ahead: focus += dir_of_motion * lookAheadDist, but ease the look-ahead offset itself toward its goal so a direction flip doesn't snap the view.
3. Smooth the camera toward the focus (section 1).
4. Clamp so the visible rectangle stays in bounds: clamp camera center to [min + halfView, max - halfView] per axis (clamp the view, not the center).

# Godot 4.7: clamp the VIEW, accounting for zoom and viewport size.
func _clamp_to_level(center: Vector2) -> Vector2:
    var half := get_viewport_rect().size * 0.5 / zoom
    return Vector2(
        clampf(center.x, level_rect.position.x + half.x, level_rect.end.x - half.x),
        clampf(center.y, level_rect.position.y + half.y, level_rect.end.y - half.y))
# If the level is smaller than the view on an axis, center on that axis instead of clamping.

Tunables: deadzone 32–64 px, look-ahead 40–120 px eased over 0.2–0.4 s, smoothing rate 6–10.

3. 3D third-person orbit

• Rig: an invisible pivot at the character's shoulder/head height; yaw on the pivot, pitch on a child; the camera sits at -springLength on local Z.
• Collision: a spring arm (Godot SpringArm3D) or occlusion ray casts from pivot to desired camera position and shortens to the first hit so the camera never clips through walls.
• Pitch clamp: ~[-80°, +45°] so the camera can't flip or bury into the floor.
• Sensitivity & invert: expose look sensitivity and invert-Y (see input-systems).
• Cinemachine 3 (Unity 6.3 LTS): a CinemachineCamera (namespace Unity.Cinemachine) with an Orbital Follow component and a Cinemachine Deoccluder (collision); the CinemachineBrain on the Camera blends between cameras. This replaces the v2 CinemachineVirtualCamera / CinemachineCollider names.

4. First-person look

• Yaw rotates the body (so movement aligns with view); pitch rotates only the camera head.
• Clamp pitch; never let roll accumulate.
• Mouse: use relative motion + capture the cursor (Input.mouse_mode = MOUSE_MODE_CAPTURED).
• Stick: apply a response curve + deadzone (see input-systems) and frame-rate-scaled turn rate.

5. Multi-target / group framing

• Compute the bounding box of all targets; place the camera at the box center.
• 2D: set zoom so the box (plus padding) fits the viewport; clamp zoom min/max.
• 3D: dolly the camera back / adjust FOV to fit the box; Cinemachine has a Group Framing / Target Group component for this.
• Split-screen: one camera per player rendering to a viewport rectangle; budget the extra render cost (performance-optimization).

6. Cinematic blends & transitions

• Blend between gameplay and cutscene cameras over a short time (ease-in-out). Cinemachine blends automatically when you change the active camera's priority; in Godot, tween a rig between marker transforms or swap current cameras with a fade.
• Reset smoothing state on hard cuts/teleports so the camera doesn't slingshot across the map.

7. Per-engine rig summary