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

public class Scanlines : ScriptableRendererFeature
{
    class ScanlinesRenderPass : ScriptableRenderPass
    {
        private Material material;
        private ScanlinesSettings settings;

        private RenderTargetIdentifier source;
        private RenderTargetHandle mainTex;
        private string profilerTag;

        public ScanlinesRenderPass(string profilerTag)
        {
            this.profilerTag = profilerTag;
        }

        public void Setup(ScriptableRenderer renderer)
        {
            source = renderer.cameraColorTarget;
            settings = VolumeManager.instance.stack.GetComponent<ScanlinesSettings>();
            renderPassEvent = RenderPassEvent.BeforeRenderingPostProcessing;

            if (settings != null && settings.IsActive())
            {
                renderer.EnqueuePass(this);
                material = new Material(Shader.Find("SnapshotProURP/Scanlines"));
            }
        }

        public override void Configure(CommandBuffer cmd, RenderTextureDescriptor cameraTextureDescriptor)
        {
            if (settings == null)
            {
                return;
            }

            mainTex = new RenderTargetHandle();
            mainTex.id = Shader.PropertyToID("MainTex");
            cmd.GetTemporaryRT(mainTex.id, cameraTextureDescriptor);

            base.Configure(cmd, cameraTextureDescriptor);
        }

        public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
        {
            if (!settings.IsActive())
            {
                return;
            }

            CommandBuffer cmd = CommandBufferPool.Get(profilerTag);

            // Copy camera color texture to MainTex.
            cmd.Blit(source, mainTex.id);

            // Set Scanlines effect properties.
            cmd.SetGlobalTexture("_ScanlineTex", settings.scanlineTex.value);
            cmd.SetGlobalFloat("_Strength", settings.strength.value);
            cmd.SetGlobalInt("_Size", settings.size.value);
            cmd.SetGlobalFloat("_ScrollSpeed", settings.scrollSpeed.value);
            
            // Execute effect using effect material.
            cmd.Blit(mainTex.id, source, material);

            context.ExecuteCommandBuffer(cmd);
            cmd.Clear();
            CommandBufferPool.Release(cmd);
        }

        public override void FrameCleanup(CommandBuffer cmd)
        {
            cmd.ReleaseTemporaryRT(mainTex.id);
        }
    }

    ScanlinesRenderPass pass;

    public override void Create()
    {
        pass = new ScanlinesRenderPass("Scanlines");
        name = "Scanlines";
    }

    public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
    {
        pass.Setup(renderer);
    }
}
