C# C2DPoint.ProjectsOnLine方法代码示例

        /// <summary>
        /// Distance to a point.
        /// </summary>
        /// <param name="ptTest">The test point.</param>
        /// <param name="ptOnThis">Output. The closest point on the triangle.</param>
	    public double Distance(C2DPoint ptTest,  C2DPoint ptOnThis)
        {
	        double dArea = GetAreaSigned();
            bool BTemp = true;
	        // Construct the lines.
	        C2DLine Line12 = new C2DLine(P1, P2);
	        C2DLine Line23 = new C2DLine(P2, P3);
            C2DLine Line31 = new C2DLine(P3, P1);

	        if (dArea == 0)
	        {
		        // Colinear so find the biggest line and return the distance from that
		        double d1 = Line12.GetLength();
		        double d2 = Line23.GetLength();
		        double d3 = Line31.GetLength();
		        if (d1 > d2 && d1 > d3)
			        return Line12.Distance(ptTest,  ptOnThis);
		        else if (d2 > d3)
			        return Line23.Distance(ptTest,  ptOnThis);
		        else
			        return Line31.Distance(ptTest,  ptOnThis);
	        }
	        // Find out it the triangle is clockwise or not.
	        bool bClockwise = dArea < 0;

	        // Set up some pointers to record the lines that the point is "above", "above" meaning that the
	        // point is on the opposite side of the line to the rest of the triangle
	        C2DLine LineAbove1 = null;
            C2DLine LineAbove2 = null;

	        // Find out which Lines have the point above.
	        if (  Line12.IsOnRight( ptTest ) ^ bClockwise  )  // if the pt is on the opposite side to the triangle
		        LineAbove1 = Line12;
	        if ( Line23.IsOnRight( ptTest ) ^ bClockwise)
	        {
		        if (LineAbove1 != null)
			        LineAbove2 = Line23;
		        else
			        LineAbove1 = Line23;
	        }
	        if ( Line31.IsOnRight( ptTest ) ^ bClockwise)
	        {
		        if (LineAbove1 != null)
		        {
			        // We can't have all the lines with the point above.
			        Debug.Assert(LineAbove2 != null);
			        LineAbove2 = Line31;
		        }
		        else
			        LineAbove1 = Line31;
	        }

	        // Check for containment (if there isn't a single line that its above then it must be inside)
	        if (LineAbove1 == null)
	        {
		        // Pt inside so project onto all the lines and find the closest projection (there must be one).
        	
		        // Set up a record of the point projection on the lines.
		        C2DPoint ptOnLine = new C2DPoint();
		        bool bSet = false;
		        double dMinDist = 0;

                if (ptTest.ProjectsOnLine(Line12,  ptOnLine,  ref BTemp))
		        {
			        dMinDist = ptTest.Distance(ptOnLine);
				    ptOnThis.Set(ptOnLine);
			        bSet = true;
		        }
                if (ptTest.ProjectsOnLine(Line23,  ptOnLine, ref BTemp))
		        {
			        double dDist = ptTest.Distance(ptOnLine);
			        if (!bSet || dDist < dMinDist)
			        {
				        dMinDist = dDist;
					    ptOnThis.Set(ptOnLine);
				        bSet = true;
			        }
		        }
                if (ptTest.ProjectsOnLine(Line31,  ptOnLine, ref BTemp))
		        {
			        double dDist = ptTest.Distance(ptOnLine);
			        if (!bSet || dDist < dMinDist)
			        {
				        dMinDist = dDist;
					    ptOnThis.Set(ptOnLine);
				        bSet = true;
			        }
		        }
		        Debug.Assert(bSet);
		        return -dMinDist; //-ve if inside
	        }
	        else if (LineAbove2 == null)
	        {
		        // it is only above 1 of the lines so simply return the distance to that line
		        return LineAbove1.Distance(ptTest,  ptOnThis);
//.........这里部分代码省略.........