///<summary>
/// Given a grid cell and an isolevel, calculate the triangular facets required to represent the isosurface through the cell.
/// Return the number of triangular facets, the array "triangles" will be loaded up with the vertices at most 5 triangular facets.
/// 0 will be returned if the grid cell is either totally above of totally below the isolevel.
///</summary>
public static int Polygonise( GRIDCELL grid, float isolevel, TRIANGLE[] triangles )
{
int i, ntriang;
int cubeindex;
Vector3[] vertlist = new Vector3[ 12 ];
// Determine the index into the edge table which tells us which vertices are inside of the surface
cubeindex = 0;
if( grid.val[ 0 ] < isolevel )
{
cubeindex |= 1;
}
if( grid.val[ 1 ] < isolevel )
{
cubeindex |= 2;
}
if( grid.val[ 2 ] < isolevel )
{
cubeindex |= 4;
}
if( grid.val[ 3 ] < isolevel )
{
cubeindex |= 8;
}
if( grid.val[ 4 ] < isolevel )
{
cubeindex |= 16;
}
if( grid.val[ 5 ] < isolevel )
{
cubeindex |= 32;
}
if( grid.val[ 6 ] < isolevel )
{
cubeindex |= 64;
}
if( grid.val[ 7 ] < isolevel )
{
cubeindex |= 128;
}
// Cube is entirely in/out of the surface
if( edgeTable[ cubeindex ] == 0 )
{
return 0;
}
// Find the vertices where the surface intersects the cube
if( ( edgeTable[ cubeindex ] & 1 ) != 0x0 )
{
vertlist[ 0 ] = VertexInterp( isolevel, grid.p[ 0 ], grid.p[ 1 ], grid.val[ 0 ], grid.val[ 1 ] );
}
if( ( edgeTable[ cubeindex ] & 2 ) != 0x0 )
{
vertlist[ 1 ] = VertexInterp( isolevel, grid.p[ 1 ], grid.p[ 2 ], grid.val[ 1 ], grid.val[ 2 ] );
}
if( ( edgeTable[ cubeindex ] & 4 ) != 0x0 )
{
vertlist[ 2 ] = VertexInterp( isolevel, grid.p[ 2 ], grid.p[ 3 ], grid.val[ 2 ], grid.val[ 3 ] );
}
if( ( edgeTable[ cubeindex ] & 8 ) != 0x0 )
{
vertlist[ 3 ] = VertexInterp( isolevel, grid.p[ 3 ], grid.p[ 0 ], grid.val[ 3 ], grid.val[ 0 ] );
}
if( ( edgeTable[ cubeindex ] & 16 ) != 0x0 )
{
vertlist[ 4 ] = VertexInterp( isolevel, grid.p[ 4 ], grid.p[ 5 ], grid.val[ 4 ], grid.val[ 5 ] );
}
if( ( edgeTable[ cubeindex ] & 32 ) != 0x0 )
{
vertlist[ 5 ] = VertexInterp( isolevel, grid.p[ 5 ], grid.p[ 6 ], grid.val[ 5 ], grid.val[ 6 ] );
}
if( ( edgeTable[ cubeindex ] & 64 ) != 0x0 )
{
vertlist[ 6 ] = VertexInterp( isolevel, grid.p[ 6 ], grid.p[ 7 ], grid.val[ 6 ], grid.val[ 7 ] );
}
if( ( edgeTable[ cubeindex ] & 128 ) != 0x0 )
{
vertlist[ 7 ] = VertexInterp( isolevel, grid.p[ 7 ], grid.p[ 4 ], grid.val[ 7 ], grid.val[ 4 ] );
}
if( ( edgeTable[ cubeindex ] & 256 ) != 0x0 )
{
vertlist[ 8 ] = VertexInterp( isolevel, grid.p[ 0 ], grid.p[ 4 ], grid.val[ 0 ], grid.val[ 4 ] );
}
if( ( edgeTable[ cubeindex ] & 512 ) != 0x0 )
{
vertlist[ 9 ] = VertexInterp( isolevel, grid.p[ 1 ], grid.p[ 5 ], grid.val[ 1 ], grid.val[ 5 ] );
}
if( ( edgeTable[ cubeindex ] & 1024 ) != 0x0 )
{
vertlist[ 10 ] = VertexInterp( isolevel, grid.p[ 2 ], grid.p[ 6 ], grid.val[ 2 ], grid.val[ 6 ] );
}
if( ( edgeTable[ cubeindex ] & 2048 ) != 0x0 )
{
vertlist[ 11 ] = VertexInterp( isolevel, grid.p[ 3 ], grid.p[ 7 ], grid.val[ 3 ], grid.val[ 7 ] );
}
// Create the triangle
ntriang = 0;
for( i = 0; triTable[ cubeindex ][ i ] != -1; i += 3 )
{
triangles[ ntriang ].p[ 2 ] = vertlist[ triTable[ cubeindex ][ i ] ];
triangles[ ntriang ].p[ 1 ] = vertlist[ triTable[ cubeindex ][ i + 1 ] ];
triangles[ ntriang ].p[ 0 ] = vertlist[ triTable[ cubeindex ][ i + 2 ] ];
( ntriang )++;
}
return ntriang;
}
///<summary>
/// Given a grid cell and an isolevel, calculate the triangular facets required to represent the isosurface through the cell.
/// Return the number of triangular facets, the array "triangles" will be loaded up with the vertices at most 5 triangular facets.
/// 0 will be returned if the grid cell is either totally above of totally below the isolevel.
///</summary>
public static int Polygonise(GRIDCELL grid, float isolevel, TRIANGLE[] triangles)
{
int i, ntriang;
int cubeindex;
Vector3[] vertlist = new Vector3[12];
// Determine the index into the edge table which tells us which vertices are inside of the surface
cubeindex = 0;
if (grid.val[0] < isolevel)
{
cubeindex |= 1;
}
if (grid.val[1] < isolevel)
{
cubeindex |= 2;
}
if (grid.val[2] < isolevel)
{
cubeindex |= 4;
}
if (grid.val[3] < isolevel)
{
cubeindex |= 8;
}
if (grid.val[4] < isolevel)
{
cubeindex |= 16;
}
if (grid.val[5] < isolevel)
{
cubeindex |= 32;
}
if (grid.val[6] < isolevel)
{
cubeindex |= 64;
}
if (grid.val[7] < isolevel)
{
cubeindex |= 128;
}
// Cube is entirely in/out of the surface
if (edgeTable[cubeindex] == 0)
{
return(0);
}
// Find the vertices where the surface intersects the cube
if ((edgeTable[cubeindex] & 1) != 0x0)
{
vertlist[0] = VertexInterp(isolevel, grid.p[0], grid.p[1], grid.val[0], grid.val[1]);
}
if ((edgeTable[cubeindex] & 2) != 0x0)
{
vertlist[1] = VertexInterp(isolevel, grid.p[1], grid.p[2], grid.val[1], grid.val[2]);
}
if ((edgeTable[cubeindex] & 4) != 0x0)
{
vertlist[2] = VertexInterp(isolevel, grid.p[2], grid.p[3], grid.val[2], grid.val[3]);
}
if ((edgeTable[cubeindex] & 8) != 0x0)
{
vertlist[3] = VertexInterp(isolevel, grid.p[3], grid.p[0], grid.val[3], grid.val[0]);
}
if ((edgeTable[cubeindex] & 16) != 0x0)
{
vertlist[4] = VertexInterp(isolevel, grid.p[4], grid.p[5], grid.val[4], grid.val[5]);
}
if ((edgeTable[cubeindex] & 32) != 0x0)
{
vertlist[5] = VertexInterp(isolevel, grid.p[5], grid.p[6], grid.val[5], grid.val[6]);
}
if ((edgeTable[cubeindex] & 64) != 0x0)
{
vertlist[6] = VertexInterp(isolevel, grid.p[6], grid.p[7], grid.val[6], grid.val[7]);
}
if ((edgeTable[cubeindex] & 128) != 0x0)
{
vertlist[7] = VertexInterp(isolevel, grid.p[7], grid.p[4], grid.val[7], grid.val[4]);
}
if ((edgeTable[cubeindex] & 256) != 0x0)
{
vertlist[8] = VertexInterp(isolevel, grid.p[0], grid.p[4], grid.val[0], grid.val[4]);
}
if ((edgeTable[cubeindex] & 512) != 0x0)
{
vertlist[9] = VertexInterp(isolevel, grid.p[1], grid.p[5], grid.val[1], grid.val[5]);
}
if ((edgeTable[cubeindex] & 1024) != 0x0)
{
vertlist[10] = VertexInterp(isolevel, grid.p[2], grid.p[6], grid.val[2], grid.val[6]);
}
if ((edgeTable[cubeindex] & 2048) != 0x0)
{
vertlist[11] = VertexInterp(isolevel, grid.p[3], grid.p[7], grid.val[3], grid.val[7]);
}
// Create the triangle
ntriang = 0;
for (i = 0; triTable[cubeindex][i] != -1; i += 3)
{
triangles[ntriang].p[2] = vertlist[triTable[cubeindex][i]];
triangles[ntriang].p[1] = vertlist[triTable[cubeindex][i + 1]];
triangles[ntriang].p[0] = vertlist[triTable[cubeindex][i + 2]];
(ntriang)++;
}
return(ntriang);
}
