// Copyright (c) 2023 Nico de Poel
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

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

#if UNITY_2018_3_OR_NEWER
[ExecuteAlways]
#else
[ExecuteInEditMode]
#endif
[RequireComponent(typeof(Camera))]
public class Passthru : MonoBehaviour
{
    public RenderTexture renderTexture;
    public RenderTexture motionVectors;

    private static readonly int CameraMotionVectors = Shader.PropertyToID("_CameraMotionVectors");

    private Camera _camera;
    private CommandBuffer _commandBuffer;

    private void OnEnable()
    {
        _camera = GetComponent<Camera>();
        
        _commandBuffer = new CommandBuffer { name = "Passthru" };
        _commandBuffer.SetGlobalTexture(CameraMotionVectors, motionVectors);
        _commandBuffer.Blit(renderTexture, BuiltinRenderTextureType.CameraTarget);
        
        _camera.AddCommandBuffer(CameraEvent.BeforeImageEffectsOpaque, _commandBuffer);
    }

    private void OnDisable()
    {
        if (_commandBuffer != null)
        {
            if (_camera != null)
                _camera.RemoveCommandBuffer(CameraEvent.BeforeImageEffectsOpaque, _commandBuffer);
            
            _commandBuffer.Release();
            _commandBuffer = null;
        }
    }
}