using System.Collections;
using System.Collections.Generic;
using UnityEngine;

/**
 * <summary>
 *  Blits a RenderTexture on the Camera in this GameObject.
 *  The RenderingCamera field controls which Camera's render target is blitted.
 *  The render target of RenderingCamera is scaled according to Options.RenderScale.
 * </summary>
 */
[RequireComponent(typeof(Camera))]
public class RenderScaler : MonoBehaviour {
    public Options Options;
    public Camera RenderingCamera;
    public float CurrentRenderScale = -1f;

    // 100ms between texture recreation should lessen the gpu load a bit
    // when moving the slider around, but still give realtime (enough) feedback.
    public float RenderScaleChangeCooldown = 0.1f;

    private RenderTexture CameraTarget;
    private float LastChange = 0;

    private void Start() {
        UpdateRenderTexture();
    }

    private void Update() {
        if (Time.unscaledTime - LastChange > RenderScaleChangeCooldown && CurrentRenderScale != Options.RenderScale) {
            LastChange = Time.unscaledTime;
            UpdateRenderTexture();
        }
    }

    private void UpdateRenderTexture() {
        CurrentRenderScale = Options.RenderScale;
        RenderingCamera.targetTexture.Release();
        RenderingCamera.targetTexture.width = (int)(Screen.width * CurrentRenderScale);
        RenderingCamera.targetTexture.height = (int)(Screen.height * CurrentRenderScale);
        RenderingCamera.targetTexture.Create();
    }

    private void OnRenderImage(RenderTexture src, RenderTexture dst) {
        Graphics.Blit(RenderingCamera.targetTexture, dst);
    }

}