[游戏开发]2021-07-14Unity:通过扫描线种子算法实现区域填充（油漆桶功能）

using System;
using System.Collections;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Runtime.Serialization.Json;
using System.Text;
using UnityEngine;
using UnityEngine.UI;
using Color = UnityEngine.Color;

public class Demo_texture : MonoBehaviour
{
//计算鼠标点击位置 对应的像素位置，一个是image的左下角，一个是图片的右上角
public Transform textureOrigin;
public Transform textureUPEnd;
//存储点击的图片的texture2D getpixel() 使用
private Texture2D clickTexture2D;
//存储鼠标点击位置的像素值
private Color testColor;
//存储计算出来的像素点的位置
private Vector2 colorPos;
//存储图片定位点的屏幕坐标
private Vector3 textureOriginScreenPosition;
private Vector3 textureEndUPScreenPosition;
//图片 (Read/Write Enabled：读/写 启用)
public Image image;
//点击区域的所变的颜色
public Color color = Color.magenta;
public Stack stackX = new Stack();
public Stack stackY = new Stack();

public Color getColor(int x, int y)
{
    //返回坐标 (x,y) 处的像素颜色
    return clickTexture2D.GetPixel(x, y);
}
public void setColor(int x, int y, Color c)
{
    //设置坐标 (x,y) 处的像素颜色
    clickTexture2D.SetPixel(x, y, c);
}
private void Start()
{
    //将 position 从世界空间变换为屏幕空间。
    textureOriginScreenPosition = Camera.main.WorldToScreenPoint(textureOrigin.position);
    textureEndUPScreenPosition = Camera.main.WorldToScreenPoint(textureUPEnd.position);
}
private void Update()
{
    //返回从摄像机通过屏幕点的光线。
    Ray r = Camera.main.ScreenPointToRay(Input.mousePosition);
    //用于从射线投射获取信息
    RaycastHit hit;
    if (Input.GetMouseButtonDown(0))
    {
        //发射射线
        if (Physics.Raycast(r, out hit))
        {
            HitColorChooseImage(hit);
        }
    }
}
private void HitColorChooseImage(RaycastHit hit)
{
    //如果射线命中
    if (hit.collider.name == "Image")
    {
        //获取到纹理引用
        clickTexture2D = hit.collider.gameObject.GetComponent<Image>().sprite.texture;
        CaculateVector2();

    }
}
private void CaculateVector2()
{
                    //鼠标当前的像素坐标位置
    colorPos.x = (Input.mousePosition.x - textureOriginScreenPosition.x) 
        / (textureEndUPScreenPosition.x - textureOriginScreenPosition.x) * clickTexture2D.width;
    colorPos.y = (Input.mousePosition.y - textureOriginScreenPosition.y) 
        / (textureEndUPScreenPosition.y - textureOriginScreenPosition.y) * clickTexture2D.height;
    Debug.Log(colorPos.x+"."+colorPos.y);
    //识别底层颜色
    // if (!(getColor((int)colorPos.x, (int)colorPos.y) == Color.white))
    // {
    //     Debug.Log(colorPos.x+","+colorPos.y);
    //     return;
    // }
    //
    stackX.Clear();
    stackY.Clear();
    int y1;
    bool spanLeft, spanRight;
    stackX.Push((int)colorPos.x);
    stackY.Push((int)colorPos.y);
    while (stackX.Count>0 && stackY.Count>0)
    {
        colorPos.x = stackX.Pop();
        colorPos.y = stackY.Pop();
        y1 = (int)colorPos.y;
        while (y1 >= 0 && getColor((int)colorPos.x, y1) == Color.white)
        {
            y1--;
        }
        y1++;
        spanLeft = false;
        spanRight = false;
        while (y1 < clickTexture2D.height && getColor((int) colorPos.x, y1) == Color.white)
        {
            setColor((int)colorPos.x, y1, color);
            if (!spanLeft && colorPos.x > 0 && getColor((int)colorPos.x - 1, y1) == Color.white)
            {
                stackX.Push((int)colorPos.x - 1);
                stackY.Push(y1);
                spanLeft = true;
            }
            else if (spanLeft && colorPos.x > 0 && getColor((int)colorPos.x - 1, y1) != Color.white)
            {
                spanLeft = false;
            }
            if (!spanRight && colorPos.x < clickTexture2D.width - 1 && getColor((int)colorPos.x + 1, y1) == Color.white)
            {
                stackX.Push((int)colorPos.x + 1);
                stackY.Push(y1);
                spanRight = true;
            }
            else if (spanRight && colorPos.x < clickTexture2D.width - 1 && getColor((int)colorPos.x + 1, y1) != Color.white)
            {
                spanRight = false;
            }
            y1++;
        }
    }
    //实际应用任何先前的 SetPixel 和 SetPixels 更改
    clickTexture2D.Apply();
}

}