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