Aetheria/Assets/SectorRenderer.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;
using Unity.Mathematics;
using static Unity.Mathematics.math;
using float2 = Unity.Mathematics.float2;

public class SectorRenderer : MonoBehaviour, IBeginDragHandler, IDragHandler, IScrollHandler
{
    public ActionGameManager GameManager;
    public Camera SectorCamera;
    public MeshRenderer SectorBackgroundRenderer;
    public float ZoomSpeed;
    public float MinViewSize = .1f;
    public float MaxViewSize = 2;

    private float2 _startMousePosition;
    private float2 _startMapPosition;

    private Transform _sectorBackgroundTransform;
    private Transform _sectorCameraTransform;
    private Image _outputImage;
    private RenderTexture _outputTexture;
    private Vector3[] _imageCorners = new Vector3[4];
    private int2 _size;
    private bool _init;
    private float _aspectRatio;
    private float _sectorBackgroundDepth;
    private float _sectorCameraDepth;
    
    private float2 _position = float2(0.5f);
    private float _viewSize = .5f;
    
    void Start()
    {
        _outputImage = GetComponent<Image>();
        _sectorBackgroundTransform = SectorBackgroundRenderer.transform;
        _sectorBackgroundDepth = _sectorBackgroundTransform.position.z;
        _sectorCameraTransform = SectorCamera.transform;
        _sectorCameraDepth = _sectorCameraTransform.position.z;
    }
    
    private void OnEnable()
    {
        _init = true;
        SectorCamera.gameObject.SetActive(true);
        _position = GameManager.Zone.SectorZone.Position;
        _viewSize = .25f;
    }

    private void OnDisable()
    {
        if (_outputTexture != null)
        {
            _outputTexture.Release();
            _outputTexture = null;
        }
        SectorCamera.gameObject.SetActive(false);
    }

    void LateUpdate()
    {
        var size = int2(Screen.width, Screen.height);
        if (_init || size.x != _size.x || size.y != _size.y)
        {
            _aspectRatio = (float) size.x / size.y;
            _size = size;
            if (_outputTexture != null)
            {
                _outputTexture.Release();
            }
            _outputTexture = new RenderTexture(_size.x, _size.y, 0, RenderTextureFormat.Default);
            SectorCamera.targetTexture = _outputTexture;
            _outputImage.material.SetTexture("_DetailTex", _outputTexture);
        }

        var halfSize = _viewSize / 2;
        var bounds = float4(
            _position.x - _aspectRatio * halfSize, 
            _position.y - halfSize, 
            _position.x + _aspectRatio * halfSize, 
            _position.y + halfSize);
        _sectorBackgroundTransform.position = new Vector3(_position.x, _position.y, _sectorBackgroundDepth);
        _sectorBackgroundTransform.localScale = new Vector3(_aspectRatio * _viewSize, _viewSize);
        _sectorCameraTransform.position = new Vector3(_position.x, _position.y, _sectorCameraDepth);
        SectorCamera.orthographicSize = halfSize;
        SectorBackgroundRenderer.material.SetVector("Extents", bounds);
    }

    public void OnBeginDrag(PointerEventData eventData)
    {
        _startMousePosition = eventData.position;
        _startMapPosition = _position;
    }

    public void OnDrag(PointerEventData eventData)
    {
        _position = _startMapPosition - ((float2)eventData.position - _startMousePosition) / _size.y * _viewSize;
    }

    public void OnScroll(PointerEventData eventData)
    {
        var mapCenter = float2((float)Screen.width / 2, (float)Screen.height / 2);
        var oldPointerPosition = _position + ((float2)eventData.position - mapCenter) / Screen.height * _viewSize;
        _viewSize = clamp(_viewSize * (1 - eventData.scrollDelta.y * ZoomSpeed), MinViewSize, MaxViewSize);
        var pointerPosition = _position + ((float2)eventData.position - mapCenter) / Screen.height * _viewSize;
        _position += oldPointerPosition - pointerPosition;
    }
}