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■ 2개 직선의 교차 여부 구하기

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TestProject.zip


MainForm.cs

 

 

using System.Collections.Generic;

using System.Drawing;

using System.Drawing.Drawing2D;

using System.Windows.Forms;

 

namespace TestProject

{

    /// <summary>

    /// 메인 폼

    /// </summary>

    public partial class MainForm : Form

    {

        //////////////////////////////////////////////////////////////////////////////////////////////////// Field

        ////////////////////////////////////////////////////////////////////////////////////////// Private

 

        #region Field

 

        /// <summary>

        /// 포인트 리스트

        /// </summary>

        private List<PointF> pointList = new List<PointF>();

 

        /// <summary>

        /// 근접점 1

        /// </summary>

        private PointF closePoint1;

        

        /// <summary>

        /// 근접점 2

        /// </summary>

        private PointF closePoint2;

        

        /// <summary>

        /// 교차점

        /// </summary>

        private PointF intersectPoint;

 

        /// <summary>

        /// 직선 교차 여부

        /// </summary>

        private bool lineIntersect = false;

 

        /// <summary>

        /// 세그먼트 교차 여부

        /// </summary>

        private bool segmentIntersect = false;

 

        #endregion

 

        //////////////////////////////////////////////////////////////////////////////////////////////////// Constructor

        ////////////////////////////////////////////////////////////////////////////////////////// Public

 

        #region 생성자 - MainForm()

 

        /// <summary>

        /// 생성자

        /// </summary>

        public MainForm()

        {

            InitializeComponent();

 

            #region 이벤트를 설정한다.

 

            MouseClick += Form_MouseClick;

            Paint      += Form_Paint;

 

            #endregion

        }

 

        #endregion

 

        //////////////////////////////////////////////////////////////////////////////////////////////////// Method

        ////////////////////////////////////////////////////////////////////////////////////////// Private

        //////////////////////////////////////////////////////////////////////////////// Event

 

        #region 폼 마우스 클릭시 처리하기 - Form_MouseClick(sender, e)

 

        /// <summary>

        /// 폼 마우스 클릭시 처리하기

        /// </summary>

        /// <param name="sender">이벤트 발생자</param>

        /// <param name="e">이벤트 인자</param>

        private void Form_MouseClick(object sender, MouseEventArgs e)

        {

            if(this.pointList.Count == 4)

            {

                this.pointList = new List<PointF>();

 

                this.lineIntersect = false;

            }

 

            this.pointList.Add(new PointF(e.X, e.Y));

 

            if(this.pointList.Count == 4)

            {

                FindIntersection

                (

                    this.pointList[0],

                    this.pointList[1],

                    this.pointList[2],

                    this.pointList[3],

                    out this.lineIntersect,

                    out this.segmentIntersect,

                    out this.intersectPoint,

                    out this.closePoint1,

                    out this.closePoint2

                );

            }

 

            Invalidate();

        }

 

        #endregion

        #region 폼 페인트시 처리하기 - Form_Paint(sender, e)

 

        /// <summary>

        /// 폼 페인트시 처리하기

        /// </summary>

        /// <param name="sender">이벤트 발생자</param>

        /// <param name="e">이벤트 인자</param>

        private void Form_Paint(object sender, PaintEventArgs e)

        {

            e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;

 

            if(this.pointList.Count == 4)

            {

                e.Graphics.DrawLine(Pens.Green, this.pointList[2], this.pointList[3]);

            }

 

            if(this.pointList.Count >= 2)

            {

                e.Graphics.DrawLine(Pens.Blue, this.pointList[0], this.pointList[1]);

            }

 

            if(this.lineIntersect)

            {

                using(Pen dashPen = new Pen(Color.Red))

                {

                    dashPen.DashStyle   = DashStyle.Custom;

                    dashPen.DashPattern = new float[] { 4, 4 };

 

                    e.Graphics.DrawLine(dashPen, this.closePoint1, this.closePoint2);

                }

            }

 

            foreach(PointF point in this.pointList)

            {

                DrawPoint(e.Graphics, point, Brushes.White, Pens.Black);

            }

 

            if(this.lineIntersect)

            {

                DrawPoint(e.Graphics, this.closePoint1   , Brushes.LightBlue, Pens.Blue);

                DrawPoint(e.Graphics, this.closePoint2   , Brushes.LightBlue, Pens.Blue);

                DrawPoint(e.Graphics, this.intersectPoint, Brushes.HotPink  , Pens.Red );

            }

        }

 

        #endregion

 

        //////////////////////////////////////////////////////////////////////////////// Function

 

        #region 포인트 그리기 - DrawPoint(graphics, point, brush, pen)

 

        /// <summary>

        /// 포인트 그리기

        /// </summary>

        /// <param name="graphics">그래픽스</param>

        /// <param name="point">포인트</param>

        /// <param name="brush">브러시</param>

        /// <param name="pen"></param>

        private void DrawPoint(Graphics graphics, PointF point, Brush brush, Pen pen)

        {

            const int RADIUS = 3;

 

            graphics.FillEllipse(brush, point.X - RADIUS, point.Y - RADIUS, 2 * RADIUS, 2 * RADIUS);

 

            graphics.DrawEllipse(pen, point.X - RADIUS, point.Y - RADIUS, 2 * RADIUS, 2 * RADIUS);

        }

 

        #endregion

        #region 교차점 찾기 - FindIntersection(p1, p2, p3, p4, lineIntersect, segmentIntersect, intersectPoint, closePoint1, closePoint2)

 

        /// <summary>

        /// 교차점 찾기

        /// </summary>

        /// <param name="p1">직선 1 포인트 1</param>

        /// <param name="p2">직선 1 포인트 2</param>

        /// <param name="p3">직선 2 포인트 1</param>

        /// <param name="p4">직선 2 포인트 2</param>

        /// <param name="lineIntersect">선 교차 여부</param>

        /// <param name="segmentIntersect">세그먼트 교차 여부</param>

        /// <param name="intersectPoint">교차점</param>

        /// <param name="closePoint1">근접점 1</param>

        /// <param name="closePoint2">근접점 2</param>

        private void FindIntersection(PointF p1, PointF p2, PointF p3, PointF p4, out bool lineIntersect, out bool segmentIntersect,

            out PointF intersectPoint, out PointF closePoint1, out PointF closePoint2)

        {

            float dx21 = p2.X - p1.X;

            float dy21 = p2.Y - p1.Y;

            float dx43 = p4.X - p3.X;

            float dy43 = p4.Y - p3.Y;

 

            float denominator = (dy21 * dx43 - dx21 * dy43);

 

            float t1 = ((p1.X - p3.X) * dy43 + (p3.Y - p1.Y) * dx43) / denominator;

 

            if(float.IsInfinity(t1))

            {

                lineIntersect     = false;

                segmentIntersect  = false;

 

                intersectPoint = new PointF(float.NaN, float.NaN);

                closePoint1    = new PointF(float.NaN, float.NaN);

                closePoint2    = new PointF(float.NaN, float.NaN);

 

                return;

            }

 

            lineIntersect = true;

 

            float t2 = ((p3.X - p1.X) * dy21 + (p1.Y - p3.Y) * dx21) / -denominator;

 

            intersectPoint = new PointF(p1.X + dx21 * t1, p1.Y + dy21 * t1);

 

            segmentIntersect = ((t1 >= 0) && (t1 <= 1) && (t2 >= 0) && (t2 <= 1));

 

            if(t1 < 0)

            {

                t1 = 0;

            }

            else if(t1 > 1)

            {

                t1 = 1;

            }

 

            if(t2 < 0)

            {

                t2 = 0;

            }

            else if(t2 > 1)

            {

                t2 = 1;

            }

 

            closePoint1 = new PointF(p1.X + dx21 * t1, p1.Y + dy21 * t1);

            closePoint2 = new PointF(p3.X + dx43 * t2, p3.Y + dy43 * t2);

        }

 

        #endregion

    }

}

 

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Posted by 사용자 icodebroker

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