230 lines
8.9 KiB
C#
230 lines
8.9 KiB
C#
using System;
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using OpenTK;
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namespace Examples.Shapes
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{
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/// <summary>winding always assumed CCW (Counter-ClockWise)</summary>
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internal struct TetrahedronFace
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{
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private Vector3d APosition, BPosition, CPosition;
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private Vector3d DPosition, Normal;
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private Vector2d ATexCoord, BTexCoord, CTexCoord;
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public TetrahedronFace( ref Vector3d apos, ref Vector2d atc,
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ref Vector3d bpos, ref Vector2d btc,
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ref Vector3d cpos, ref Vector2d ctc,
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ref Vector3d dpos,
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ref Vector3d normal )
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{
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APosition = apos; ATexCoord = atc;
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BPosition = bpos; BTexCoord = btc;
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CPosition = cpos; CTexCoord = ctc;
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DPosition = dpos;
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Normal = normal;
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}
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/// <summary>Expects CCW triangle order as input, emits 4 new CCW triangles.</summary>
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/// <param name="first">1st output Triangle</param>
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/// <param name="second">2nd output Triangle</param>
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/// <param name="third">3rd output Triangle</param>
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/// <param name="fourth">4th output Triangle</param>
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public void SubdivideSierpinski( out TetrahedronFace first, out TetrahedronFace second, out TetrahedronFace third, out TetrahedronFace fourth )
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{
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Vector3d temp;
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// find the 3 points AB, BC, CA
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Vector3d CenterAB;
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Vector3d.Add( ref this.APosition, ref this.BPosition, out temp );
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Vector3d.Multiply( ref temp, 0.5f, out CenterAB );
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Vector3d CenterBC;
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Vector3d.Add( ref this.BPosition, ref this.CPosition, out temp );
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Vector3d.Multiply( ref temp, 0.5f, out CenterBC );
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Vector3d CenterCA;
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Vector3d.Add( ref this.CPosition, ref this.APosition, out temp );
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Vector3d.Multiply( ref temp, 0.5f, out CenterCA );
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// find the 3 points AD, BD, CD
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Vector3d CenterAD;
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Vector3d.Lerp( ref this.APosition, ref this.DPosition, 0.5, out CenterAD );
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Vector3d CenterBD;
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Vector3d.Lerp( ref this.BPosition, ref this.DPosition, 0.5, out CenterBD );
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Vector3d CenterCD;
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Vector3d.Lerp( ref this.CPosition, ref this.DPosition, 0.5, out CenterCD );
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// emit 4 new CCW triangles
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first = new TetrahedronFace( ref this.APosition, ref this.ATexCoord,
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ref CenterAB, ref this.BTexCoord,
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ref CenterCA, ref this.CTexCoord,
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ref CenterAD,
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ref this.Normal );
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second = new TetrahedronFace( ref CenterAB, ref this.ATexCoord,
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ref this.BPosition, ref this.BTexCoord,
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ref CenterBC, ref this.CTexCoord,
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ref CenterBD,
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ref this.Normal );
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third = new TetrahedronFace( ref CenterCA, ref this.ATexCoord,
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ref CenterBC, ref this.BTexCoord,
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ref this.CPosition, ref this.CTexCoord,
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ref CenterCD,
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ref this.Normal );
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fourth = new TetrahedronFace( ref CenterAD, ref this.ATexCoord,
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ref CenterBD, ref this.BTexCoord,
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ref CenterCD, ref this.CTexCoord,
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ref this.DPosition,
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ref this.Normal );
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}
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internal void SubdivideKoch( double height, out TetrahedronFace first, out TetrahedronFace second, out TetrahedronFace third, out TetrahedronFace fourth, out TetrahedronFace fifth, out TetrahedronFace sixth )
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{
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Vector3d CenterAB, CenterBC, CenterCA, CenterD;
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Vector2d TexCoordAB, TexCoordBC, TexCoordCA, TexCoordD;
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Vector3d.Lerp( ref this.APosition, ref this.BPosition, 0.5, out CenterAB );
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Vector3d.Lerp( ref this.BPosition, ref this.CPosition, 0.5, out CenterBC );
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Vector3d.Lerp( ref this.CPosition, ref this.APosition, 0.5, out CenterCA );
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CenterD = CenterAB;
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Vector3d.Add(ref CenterD, ref CenterBC, out CenterD);
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Vector3d.Add(ref CenterD, ref CenterCA, out CenterD);
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CenterD /= 3.0;
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Vector3d E = CenterD + ( this.Normal * 0.5 );
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Vector3d temp = this.Normal;
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temp *= height;
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Vector3d.Add(ref CenterD, ref temp, out CenterD);
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Vector2d.Lerp( ref this.ATexCoord, ref this.BTexCoord, 0.5, out TexCoordAB );
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Vector2d.Lerp( ref this.BTexCoord, ref this.CTexCoord, 0.5, out TexCoordBC );
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Vector2d.Lerp( ref this.CTexCoord, ref this.ATexCoord, 0.5, out TexCoordCA );
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TexCoordD = TexCoordAB;
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Vector2d.Add(ref TexCoordD, ref TexCoordBC, out TexCoordD);
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Vector2d.Add(ref TexCoordD, ref TexCoordCA, out TexCoordD);
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TexCoordD /= 3.0;
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#region 1
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first.APosition = this.APosition;
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first.ATexCoord = this.ATexCoord;
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first.BPosition = CenterAB;
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first.BTexCoord = TexCoordAB;
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first.CPosition = CenterCA;
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first.CTexCoord = TexCoordCA;
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first.Normal = this.Normal;
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temp = ( this.APosition + CenterAB + CenterCA );
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temp /= 3.0;
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temp += this.Normal * -1.0;
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first.DPosition = temp;
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#endregion 1
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#region 2
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second.APosition = CenterAB;
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second.ATexCoord = TexCoordAB;
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second.BPosition = this.BPosition;
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second.BTexCoord = this.BTexCoord;
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second.CPosition = CenterBC;
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second.CTexCoord = TexCoordBC;
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second.Normal = this.Normal;
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temp = CenterAB + this.BPosition + CenterBC;
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temp /= 3.0;
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temp += this.Normal * -1.0;
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second.DPosition = temp;
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#endregion 2
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#region 3
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third.APosition = CenterBC;
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third.ATexCoord = TexCoordBC;
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third.BPosition = this.CPosition;
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third.BTexCoord = this.CTexCoord;
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third.CPosition = CenterCA;
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third.CTexCoord = TexCoordCA;
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third.Normal = this.Normal;
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temp = CenterBC + this.CPosition + CenterCA;
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temp /= 3.0;
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temp += this.Normal * -1.0;
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third.DPosition = temp;
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#endregion 3
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#region 4
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fourth.APosition = CenterAB;
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fourth.ATexCoord = TexCoordAB;
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fourth.BPosition = CenterD;
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fourth.BTexCoord = TexCoordD;
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fourth.CPosition = CenterCA;
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fourth.CTexCoord = TexCoordCA;
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SierpinskiTetrahedron.FindNormal( ref CenterAB, ref CenterD, ref CenterCA, out fourth.Normal );
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fourth.DPosition = E;
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#endregion 4
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#region 5
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fifth.APosition = CenterAB;
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fifth.ATexCoord = TexCoordAB;
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fifth.BPosition = CenterBC;
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fifth.BTexCoord = TexCoordBC;
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fifth.CPosition = CenterD;
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fifth.CTexCoord = TexCoordD;
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SierpinskiTetrahedron.FindNormal( ref CenterAB, ref CenterBC, ref CenterD, out fifth.Normal );
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fifth.DPosition = E;
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#endregion 5
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#region 6
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sixth.APosition = CenterBC;
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sixth.ATexCoord = TexCoordBC;
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sixth.BPosition = CenterCA;
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sixth.BTexCoord = TexCoordCA;
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sixth.CPosition = CenterD;
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sixth.CTexCoord = TexCoordD;
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SierpinskiTetrahedron.FindNormal( ref CenterBC, ref CenterCA, ref CenterD, out sixth.Normal );
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sixth.DPosition = E;
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#endregion 6
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}
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/// <summary>Returns 3 Vertices which form a CCW triangle.</summary>
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public void GetVertices( out VertexT2dN3dV3d first, out VertexT2dN3dV3d second, out VertexT2dN3dV3d third )
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{
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first.TexCoord = this.ATexCoord;
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first.Normal = this.Normal;
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first.Position = this.APosition;
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second.TexCoord = this.BTexCoord;
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second.Normal = this.Normal;
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second.Position = this.BPosition;
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third.TexCoord = this.CTexCoord;
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third.Normal = this.Normal;
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third.Position = this.CPosition;
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}
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/// <summary>Debugging Aid, no real purpose</summary>
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public override string ToString()
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{
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return "A= " + this.APosition.ToString() + " TexCoord: " + this.ATexCoord.ToString() + "\n" +
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"B= " + this.BPosition.ToString() + " TexCoord: " + this.ATexCoord.ToString() + "\n" +
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"C= " + this.CPosition.ToString() + " TexCoord: " + this.ATexCoord.ToString() + "\n" +
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"Normal= " + this.Normal.ToString();
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}
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}
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}
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