# Camera Screen Adaptation System

Adapts your 2D orthographic camera to different aspect ratios while keeping gameplay/UI elements aligned to screen edges. Includes a reference marker for target content width and utilities for edge anchoring.

## Table of Contents
- [What This Solves](#what-this-solves)
- [Architecture at a Glance](#architecture-at-a-glance)
- [Quick Start (Code-First)](#quick-start-code-first)
  - [Create and Wire Components in Code](#create-and-wire-components-in-code)
  - [Manual Recalculate / Listen for Changes](#manual-recalculate--listen-for-changes)
- [Components](#components)
  - [`ScreenReferenceMarker`](#screenreferencemarker)
  - [`CameraScreenAdapter`](#camerascreenadapter)
  - [`EdgeAnchor`](#edgeanchor)
- [Common Case Studies](#common-case-studies)
  - [HUD Top Bar (safe top margin)](#hud-top-bar-safe-top-margin)
  - [Side Buttons (left/right margins)](#side-buttons-leftright-margins)
  - [Cinemachine Virtual Camera](#cinemachine-virtual-camera)
- [Tips & Best Practices](#tips--best-practices)
- [Troubleshooting / FAQ](#troubleshooting--faq)
- [Paths & Namespaces](#paths--namespaces)
- [Change Log](#change-log)

## What This Solves
- Consistent horizontal framing across devices: a fixed target world-space width always fits the screen.
- Stable world-space margins from the physical screen edges for placing HUD/world elements.
- Works with both a regular `Camera` and `Cinemachine`'s `CinemachineCamera`.

## Architecture at a Glance
- Reference: `ScreenReferenceMarker` defines `targetWidth` and world-space margins (`topMargin`, `bottomMargin`, `leftMargin`, `rightMargin`).
- Adapter: `CameraScreenAdapter` computes orthographic size from `targetWidth` and aspect and applies it to the controlled camera. Emits `OnCameraAdjusted`.
- Anchoring: `EdgeAnchor` positions objects relative to the computed screen edges using the same marker margins.

## Quick Start (Code-First)

### Create and Wire Components in Code
```csharp
using AppleHillsCamera;
using UnityEngine;

public class CameraAdaptationBootstrap : MonoBehaviour
{
    [SerializeField] private Camera mainCamera; // assign in inspector or find at runtime

    private void Awake()
    {
        // 1) Create/locate the marker
        var markerGO = new GameObject("ScreenReferenceMarker");
        var marker = markerGO.AddComponent<ScreenReferenceMarker>();
        marker.targetWidth = 16f; // your desired world-space width
        marker.topMargin = 1f;    // tune margins for your HUD

        // 2) Set up the adapter on your camera
        var adapter = mainCamera.gameObject.AddComponent<CameraScreenAdapter>();
        adapter.referenceMarker = marker;
        adapter.adjustOnStart = true;
        adapter.adjustOnScreenResize = true;

        // 3) Anchor a sample HUD object to the top edge
        var hud = GameObject.CreatePrimitive(PrimitiveType.Quad);
        var anchor = hud.AddComponent<EdgeAnchor>();
        anchor.referenceMarker = marker;
        anchor.anchor = EdgeAnchor.AnchorEdge.Top;
        anchor.additionalOffset = 0.25f; // extra spacing from the top margin
        anchor.continuousUpdate = true;  // keep tracking when aspect changes
    }
}
```

### Manual Recalculate / Listen for Changes
```csharp
using AppleHillsCamera;
using UnityEngine;

public class CameraAdaptationHooks : MonoBehaviour
{
    [SerializeField] private CameraScreenAdapter adapter;

    private void OnEnable()
    {
        // Listen when the camera size is applied
        adapter.OnCameraAdjusted += OnAdjusted;
    }

    private void OnDisable()
    {
        adapter.OnCameraAdjusted -= OnAdjusted;
    }

    public void ForceRecalculateNow()
    {
        adapter.AdjustCamera();
    }

    private void OnAdjusted()
    {
        Debug.Log("Camera adjusted to match target width.");
        // Reposition custom elements if you don’t use EdgeAnchor
    }
}
```

## Components

### `ScreenReferenceMarker`
Defines the reference sizes and margins used by both the adapter and anchors.

Key fields:
- `targetWidth` (float): world-space width that should fully fit the viewport.
- `topMargin`, `bottomMargin`, `leftMargin`, `rightMargin` (float): world-space distances from the corresponding screen edges.
- Scene gizmos: visualizes width line, screen rectangle, and margin guides in the editor.

Typical setup:
- Place at the world-space center of your playable area or camera focus.
- Tune margins to match your HUD/world layout needs.

### `CameraScreenAdapter`
Computes and applies orthographic size to a `Camera` or `CinemachineCamera` so that the screen horizontally fits `targetWidth`.

Highlights:
- Fields: `referenceMarker`, `adjustOnStart`, `adjustOnScreenResize`.
- Event: `OnCameraAdjusted` fires after a size update.
- Works with built-in `Camera` (must be orthographic) or with `CinemachineCamera`.

Formula:
- `orthoSize = (targetWidth / 2f) * (Screen.height / Screen.width)`.

Public helpers:
- `AdjustCamera()` — recalculate and apply now.
- `GetControlledCamera()` — returns the underlying `Camera` instance.

### `EdgeAnchor`
Anchors a `Transform` to a chosen screen edge using the same marker margins.

Common fields (names based on code):
- `referenceMarker` (`ScreenReferenceMarker`)
- `anchor` (`EdgeAnchor.AnchorEdge`): `Top`, `Bottom`, `Left`, `Right`
- `additionalOffset` (float): extra spacing beyond the margin
- `continuousUpdate` (bool): update every frame and on camera adjustments

Usage tips:
- Use `continuousUpdate` for elements that must track aspect changes at runtime.
- Combine with local offsets/parenting for precise UI/HUD placements in world space.

## Common Case Studies

### HUD Top Bar (safe top margin)
- Set `marker.topMargin` to the vertical padding you want from the top edge.
- Add `EdgeAnchor` to your top bar root:
```csharp
anchor.anchor = EdgeAnchor.AnchorEdge.Top;
anchor.additionalOffset = 0.1f; // small breathing room
```
- Keep `continuousUpdate = true` for device rotation/platform switches.

### Side Buttons (left/right margins)
- For a left button column:
```csharp
anchor.anchor = EdgeAnchor.AnchorEdge.Left;
anchor.additionalOffset = 0.2f;
```
- Mirror for right side with `Right`.
- Adjust `marker.leftMargin/rightMargin` to push them inward safely.

### Cinemachine Virtual Camera
- Add `CameraScreenAdapter` to the GameObject with `CinemachineCamera`.
- The adapter detects Cinemachine and writes to `Lens.OrthographicSize`.
- Everything else (margins and `EdgeAnchor`) works the same.

## Tips & Best Practices
- Pick a `targetWidth` that matches the core gameplay area horizontally; verify extremes (16:9, 19.5:9, 4:3).
- Prefer `EdgeAnchor` for HUD/world labels instead of manual scripts—anchors auto-update on resize and on `OnCameraAdjusted`.
- For one-off bespoke layouts, listen to `OnCameraAdjusted` and move objects yourself.
- Ensure regular cameras are set to `orthographic`; the adapter warns if not.

## Troubleshooting / FAQ
- My camera didn’t change size:
  - Ensure `referenceMarker` is assigned.
  - For built-in `Camera`, confirm `orthographic` is enabled.
  - If using Cinemachine, verify the component is `CinemachineCamera` on the same GameObject.
- Anchored objects are offset oddly:
  - Check `additionalOffset` and your object’s pivot/bounds.
  - Verify marker margins and that the marker sits at the world center you expect.
- It works in Play but gizmos look wrong in Scene:
  - Scene gizmos approximate using Scene/Game view sizes; rely on Play Mode for truth.

## Paths & Namespaces
- Scripts: `Assets/Scripts/AppleHillsCamera/`
  - `ScreenReferenceMarker.cs`
  - `CameraScreenAdapter.cs`
  - `EdgeAnchor.cs`
- Namespace: `AppleHillsCamera`

## Change Log
- v1.1: Added Table of Contents, code-first snippets, case studies, and aligned terms with actual APIs (`OnCameraAdjusted`, Cinemachine support).
- v1.0: Original overview and setup guide.