rj-action-library/Runtime/Procedural/MeshGeometry.cs

using System.Collections;
using System.Collections.Generic;
using Godot;
using System;



namespace Rokojori
{
  public class MeshGeometry
  {
    public List<Vector3> vertices;
    public List<int> indices;

    public List<Vector3> normals;
    public List<Vector2> uvs;
    public List<Vector2> uv2s;
    public List<Color> colors;

    public int numTriangles => indices.Count / 3;
    

    public void ForEachTriangle( Action<int,int,int,int> callback )
    {
      var index = 0;

      for ( int i = 0; i < indices.Count; i += 3 )
      {
        var a = indices[ i + 0 ];
        var b = indices[ i + 1 ];
        var c = indices[ i + 2 ];

        callback( index, a, b, c );

        index ++;
      }
    }

    public MeshGeometry UniqueTriangles()
    {
      var mg = new MeshGeometry();

      mg.Initialize( true, true, colors != null, uv2s != null );

      if ( colors != null )
      {
        mg.colors = new List<Color>();
      }

      if ( uv2s != null )
      {
        mg.uv2s = new List<Vector2>();
      }      

      ForEachTriangle(
        ( index, a, b, c )=>
        {
          var vA = vertices[ a ];
          var vB = vertices[ b ];
          var vC = vertices[ c ];

          var uvA = uvs[ a ];
          var uvB = uvs[ b ];
          var uvC = uvs[ c ];

          var nA = normals[ a ];
          var nB = normals[ b ];
          var nC = normals[ c ];

          mg.AddTriangle( 
            vA, vB, vC,
            nA, nB, nC,
            uvA, uvB, uvC
          );

          if ( colors != null )
          {
            Lists.Add( mg.colors, colors[ a ], colors[ b ], colors[ c ] );
          }

          if ( uv2s != null )
          {
            Lists.Add( mg.uv2s, uv2s[ a ], uv2s[ b ], uv2s[ c ] );
          }

        }
      );

      return mg;
    }

    public void SetTriangleUVs( int triangleIndex, Vector2 uv )
    {
      var i = triangleIndex * 3;

      var a = indices[ i + 0 ];
      var b = indices[ i + 1 ];
      var c = indices[ i + 2 ];

      uvs[ a ] = uv;
      uvs[ b ] = uv;
      uvs[ c ] = uv;
    }

    public void SetTriangleNormal( int triangleIndex, Vector3 normal )
    {
      var i = triangleIndex * 3;

      var a = indices[ i + 0 ];
      var b = indices[ i + 1 ];
      var c = indices[ i + 2 ];

      normals[ a ] = normal;
      normals[ b ] = normal;
      normals[ c ] = normal;
    }

    public void SetTriangleColor( int triangleIndex, Color color )
    {
      var i = triangleIndex * 3;

      var a = indices[ i + 0 ];
      var b = indices[ i + 1 ];
      var c = indices[ i + 2 ];

      colors[ a ] = color;
      colors[ b ] = color;
      colors[ c ] = color;
    }

    public void Initialize( bool normals = true, bool uvs = true, bool colors = false, bool uvs2 = false)
    {
      this.vertices = new List<Vector3>();
      this.indices = new List<int>();
      
      this.normals = normals ? new List<Vector3>() : null;
      this.uvs = uvs ? new List<Vector2>() : null;
      this.uv2s = uvs2 ? new List<Vector2>() : null;
      this.colors = colors ? new List<Color>() : null;      
    }


    public void AddTriangle( 
      Vector3 va, Vector3 vb, Vector3 vc, 
      Vector3 na, Vector3 nb, Vector3 nc,
      Vector2 uva, Vector2 uvb, Vector2 uvc
    )
    {
      var index = vertices.Count;
      Lists.Add( vertices, va, vb, vc );
      Lists.Add( normals, na, nb, nc );
      Lists.Add( uvs, uva, uvb, uvc );
      Lists.Add( indices, index, index + 1, index + 2 );
    }

   

    public void AddTriangle( 
      Vector3 va, Vector3 vb, Vector3 vc, 
      Vector2 uva, Vector2 uvb, Vector2 uvc
    )
    {
      var n = Vector3.Up;

      AddTriangle( va, vb, vc, 
                   n, n, n,
                   uva, uvb, uvc );
    }

    

    public void AddTriangle( Vector3 va, Vector3 vb, Vector3 vc )    
    {
      var n  = Vector3.Up;
      var uv = Vector2.Zero;

      AddTriangle( va, vb, vc,  n, n, n, uv, uv, uv );
    }

     public void AddQuad(
      Vector3 va, Vector3 vb, Vector3 vc, Vector3 vd,
      Vector3 na, Vector3 nb, Vector3 nc, Vector3 nd, 
      Vector2 uva, Vector2 uvb, Vector2 uvc, Vector2 uvd
    )
    {
      AddTriangle( va, vb, vc,  na, nb, nc,  uva, uvb, uvc );
      AddTriangle( vc, vd, va,  nc, nd, na,  uvc, uvd, uva );
    }


    public void AddQuad(
      Vector3 va, Vector3 vb, Vector3 vc, Vector3 vd,
      Vector2 uva, Vector2 uvb, Vector2 uvc, Vector2 uvd
    )
    {

      AddTriangle( va, vb, vc, uva, uvb, uvc );
      AddTriangle( vc, vd, va, uvc, uvd, uva );
    }

    public void AddQuad(  Vector3 va, Vector3 vb, Vector3 vc, Vector3 vd  )
    {
      AddQuad(
        va, vb, vc, vd,
        new Vector2( 0, 0 ),
        new Vector2( 0, 1 ),
        new Vector2( 1, 1 ),
        new Vector2( 1, 0 )
      );
    }

    public void AddQuad( Vector3 offset, float size  )
    {
      var center = new Vector3( 0.5f, 0.5f, 0 );

      /*
      
      [-0.5, -0.5]  [0.5, -0.5 ]  
      [-0.5,  0.5]  [0.5,  0.5 ]  

      */

      AddQuad(        
        new Vector3( -0.5f, -0.5f, 0 ) * size + offset ,
        new Vector3( -0.5f,  0.5f, 0 ) * size + offset ,
        new Vector3(  0.5f,  0.5f, 0 ) * size + offset ,
        new Vector3(  0.5f, -0.5f, 0 ) * size + offset 
      );
    } 

    public void AddConvex2( Convex2 convex )
    {
      var points = convex.points;
      var tris = points.Count - 2;

      for ( int i = 0; i < tris; i++ )
      {
        var p0 = Math3D.XYasXZ( points[ 0 ] );
        var p1 = Math3D.XYasXZ( points[ i + 1 ] );
        var p2 = Math3D.XYasXZ( points[ i + 2 ] );

        AddTriangle( p0, p1, p2 );
      }
    }
    


    public ArrayMesh GenerateMesh( Mesh.PrimitiveType type = Mesh.PrimitiveType.Triangles, ArrayMesh arrayMesh = null )
    {
      if ( arrayMesh == null )
      {
        arrayMesh = new ArrayMesh();
      }

      var surfaceArray = new Godot.Collections.Array();
      surfaceArray.Resize( (int) Mesh.ArrayType.Max );

      if ( vertices != null && vertices.Count != 0 )
      {
        surfaceArray[ (int) Mesh.ArrayType.Vertex ] = vertices.ToArray();
      }

      if ( normals != null && normals.Count != 0 )
      {
        surfaceArray[ (int) Mesh.ArrayType.Normal ] = normals.ToArray();
      }

      if ( uvs != null && uvs.Count != 0 )
      {
        surfaceArray[ (int) Mesh.ArrayType.TexUV ] = uvs.ToArray();
      }

      if ( uv2s != null && uv2s.Count != 0 )
      {
        surfaceArray[ (int) Mesh.ArrayType.TexUV2 ] = uv2s.ToArray();
      }

      if ( colors != null && colors.Count != 0 )
      {
        surfaceArray[ (int) Mesh.ArrayType.Color ] = colors.ToArray();
      }

      if ( indices != null && indices.Count != 0 )
      {
        surfaceArray[ (int) Mesh.ArrayType.Index ] = indices.ToArray();
      }

      arrayMesh.AddSurfaceFromArrays( Mesh.PrimitiveType.Triangles, surfaceArray );

      return arrayMesh;
    }

  }
}