using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;
namespace DongWuYiXue.DaoNiaoShu
{
    public class DrawOn3D : MonoBehaviour
    {
        public Color paintColor = Vector4.one;
        [Range(10, 200)] public int paintSize = 60;
        [Range(0.2f, 10)] public float paintHardness = 1;
        [Range(0, 1.0f)] public float fullRatio = 1f;

        public UnityAction<bool> drawFull;
        public Texture2D brushTexture;
        public Transform mq;
        /// <summary>
        /// 主摄像机
        /// </summary>
        private Camera cam;

        [SerializeField]
        private ComputeShader computer;
        [SerializeField]
        private ComputeShader clearDraw;
        [SerializeField]
        private Shader drawShader;
        [SerializeField]
        private Shader blitShader;


        private ComputeBuffer value;
        private int[] full = new int[1];
        private int[] full2 = new int[1];

        private RenderTexture rt2;
        private Material mat;
        private Material matblit;
        private bool isFull = false;
        private Mesh mesh;
        int limit;

        //public GameObject hand1;
        //public GameObject hand2;
        void Start()
        {
            cam = Camera.main;
            //ComputeBufferType.IndirectArguments认定此buffer大小必须为12字节
            value = new ComputeBuffer(1, 4, ComputeBufferType.IndirectArguments);
            rt2 = new RenderTexture(512, 512, 8);
            rt2.enableRandomWrite = true;
            rt2.Create();
            mat = new Material(drawShader);
            matblit = new Material(blitShader);
            mesh = GetComponent<SkinnedMeshRenderer>().sharedMesh;

            limit = rt2.width * rt2.height;
        }

        // 在RenderTexture的(x,y)坐标处画笔刷图案
        private void Draw(int x, int y)
        {
            //绘制rendertexture
            RenderTexture.active = rt2;
            GL.PushMatrix();
            GL.LoadPixelMatrix(0, rt2.width, rt2.height, 0);
            // 绘制贴图
            x -= (int)(paintSize * 0.5f);
            y -= (int)(paintSize * 0.5f);
            Rect rect = new Rect(x, y, paintSize, paintSize);//brushTexture.width, brushTexture.height);
            mat.SetColor("_BaseColor", paintColor);
            mat.SetFloat("_PaintHardness", paintHardness);
            Graphics.DrawTexture(rect, brushTexture, mat, 0);
            // 弹出改变
            GL.PopMatrix();
            RenderTexture.active = null;

            //检测是否绘制满不用每帧执行，这里隔一帧执行一次
            //if (run)
            //{
                full[0] = 0;
                value.SetData(full);
                computer.SetTexture(0, "Result", rt2);
                computer.SetBuffer(0, "Full", value);
                computer.Dispatch(0, rt2.width / 8, rt2.height / 8, 1);
                value.GetData(full2);
            //}
            //run = !run;
            //full2等于1表示绘制满，等于0表示没有绘制满
            if (full2[0] > limit * fullRatio)
            {
                drawFull?.Invoke(true);
                isFull = true;
                Debug.Log("已经画满");
            }
        }

        private void Update()
        {
            if (Physics.Raycast(mq.localPosition, mq.forward, out RaycastHit hit))
            {
                // hit.textureCoord是碰撞点的uv值，uv值是从0到1的，所以要乘以宽高才能得到具体坐标点
                var x = (int)(hit.textureCoord.x * rt2.width) % rt2.width;
                // 注意，uv坐标系和Graphics坐标系的y轴方向相反
                var y = (int)(rt2.height - hit.textureCoord.y * rt2.height) % rt2.height;
                Draw(x, y);
            }
            //渲染绘制的画面
            matblit.SetTexture("_MainTex", rt2);
            matblit.SetColor("_BaseColor", paintColor);
            Graphics.DrawMesh(mesh, transform.localToWorldMatrix, matblit, 0);
        }

        public void ClearDraw()
        {
            clearDraw.SetTexture(0, "Result", rt2);
            clearDraw.Dispatch(0, rt2.width / 8, rt2.height / 8, 1);
            //清除画板后，画满回调可再次触发
            isFull = false;
        }
        private void OnDestroy()
        {
            rt2.Release();
            value.Release();
            rt2 = null;
            value = null;
        }
    }
}