135 lines
2.7 KiB
C#
135 lines
2.7 KiB
C#
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// Modified code from: http://wiki.unity3d.com/index.php?title=Triangulator
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using UnityEngine;
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using System.Collections.Generic;
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namespace AmplifyImpostors
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{
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public class Triangulator
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{
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private List<Vector2> m_points = new List<Vector2>();
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public List<Vector2> Points { get { return m_points; } }
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public Triangulator( Vector2[] points )
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{
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m_points = new List<Vector2>( points );
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}
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public Triangulator( Vector2[] points, bool invertY = true )
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{
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if( invertY )
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{
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m_points = new List<Vector2>();
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for( int i = 0; i < points.Length; i++ )
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{
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m_points.Add( new Vector2( points[ i ].x, 1 - points[ i ].y ) );
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}
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}
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else
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{
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m_points = new List<Vector2>( points );
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}
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}
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public int[] Triangulate()
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{
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List<int> indices = new List<int>();
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int n = m_points.Count;
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if( n < 3 )
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return indices.ToArray();
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int[] V = new int[ n ];
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if( Area() > 0 )
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{
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for( int v = 0; v < n; v++ )
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V[ v ] = v;
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}
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else
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{
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for( int v = 0; v < n; v++ )
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V[ v ] = ( n - 1 ) - v;
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}
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int nv = n;
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int count = 2 * nv;
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for( int m = 0, v = nv - 1; nv > 2; )
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{
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if( ( count-- ) <= 0 )
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return indices.ToArray();
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int u = v;
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if( nv <= u )
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u = 0;
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v = u + 1;
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if( nv <= v )
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v = 0;
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int w = v + 1;
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if( nv <= w )
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w = 0;
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if( Snip( u, v, w, nv, V ) )
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{
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int a, b, c, s, t;
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a = V[ u ];
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b = V[ v ];
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c = V[ w ];
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indices.Add( a );
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indices.Add( b );
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indices.Add( c );
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m++;
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for( s = v, t = v + 1; t < nv; s++, t++ )
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V[ s ] = V[ t ];
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nv--;
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count = 2 * nv;
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}
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}
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indices.Reverse();
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return indices.ToArray();
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}
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private float Area()
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{
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int n = m_points.Count;
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float A = 0.0f;
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for( int p = n - 1, q = 0; q < n; p = q++ )
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{
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Vector2 pval = m_points[ p ];
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Vector2 qval = m_points[ q ];
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A += pval.x * qval.y - qval.x * pval.y;
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}
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return ( A * 0.5f );
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}
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private bool Snip( int u, int v, int w, int n, int[] V )
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{
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int p;
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Vector2 A = m_points[ V[ u ] ];
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Vector2 B = m_points[ V[ v ] ];
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Vector2 C = m_points[ V[ w ] ];
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if( Mathf.Epsilon > ( ( ( B.x - A.x ) * ( C.y - A.y ) ) - ( ( B.y - A.y ) * ( C.x - A.x ) ) ) )
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return false;
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for( p = 0; p < n; p++ )
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{
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if( ( p == u ) || ( p == v ) || ( p == w ) )
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continue;
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Vector2 P = m_points[ V[ p ] ];
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if( InsideTriangle( P, A, B, C ) )
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return false;
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}
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return true;
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}
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private bool InsideTriangle( Vector2 pt, Vector2 v1, Vector2 v2, Vector2 v3 )
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{
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bool b1, b2, b3;
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b1 = pt.Cross( v1, v2 ) < 0.0f;
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b2 = pt.Cross( v2, v3 ) < 0.0f;
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b3 = pt.Cross( v3, v1 ) < 0.0f;
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return ( ( b1 == b2 ) && ( b2 == b3 ) );
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}
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}
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}
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