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Displacement.cs
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Displacement.cs
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Shovel
{
// Unbaked subdivided displacements are made of 4 meshes which connect in the middle,
// but have their own vertices. (the middle edges have overlapping verts)
// Indices start from the outermost corner of each mesh and increase sequentially in rows.
// The first row goes to the right/clockwise from the initial corner (when seen from above).
// Subdivision level 2 indices
// 18---21--24 11---10---9
// | | | | | |
// | | | | | |
// 19---22--25 14---13---12
// | | | | | |
// | | | | | |
// 20---23--26 17---16---15
// 33---34--35 8----5----2
// | | | | | |
// | | | | | |
// 30---31--32 7----4----1
// | | | | | |
// | | | | | |
// 27---28--29 6----3----0
// Subdivision level 3 indices
// 50--x---x---x---x x---x---x--26---25
// | | | | | | | | | |
// 51--x---x---x---x x---x---x---x---x
// | | | | | | | | | |
// x---x---x---x---x x---x---x---x---x
// | | | | | | | | | |
// x---x---x---x---x x---x---x---x---x
// | | | | | | | | | |
// x---x---x---x---x x---x---x---x---x
// x---x---x---x---x 24--19--14---9---4
// | | | | | | | | | |
// x---x---x---x---x 23--18--13---8---3
// | | | | | | | | | |
// x---x---x---x---x 22--17--12---7---2
// | | | | | | | | | |
// x---x---x---x---x 21--16--11---6---1
// | | | | | | | | | |
// 75--76--x---x---x 20--15--10---5---0
// Vertices per mesh in each subdivision level
// Level 1: 2^2 = 4
// Level 2: ((2*2)-1)^2 3^2 = 9
// Level 3: ((3*2)-1)^2 5^2 = 25
// Level 4: ... 9^2 = 81
// Level 5: ... 17^2 = 289
// Level 6 (level 5 + quad slice 1x1): 33^2 = 1089
// Level 7: 65^2 = 4225
// Level 8: 129^2 = 16641
// Level 9: 257^2 = 66049
// Level 10: 513^2 = 263169
// Total vertices in displacement (including overlaps)
// Level 1: 16
// Level 2: 36
// Level 3: 100
// Level 4: 324
// Level 5: 1156
// Level 6: 4356
// Level 7: 21125
// Level 8: 66564
// Level 9: 264196
// Level 10: 1052676
// Image resolution (overlapping verts count as 1 pixel)
// Level 1: 3x3
// Level 2: 5x5
// Level 3: 9x9
// Level 4: 17x17
// Level 5: 33x33
// Level 6: 65x65
// Level 7: 129x129
// Level 8: 257x257
// Level 9: 513x513
// Level 10: 1025x1025
class Displacement
{
public uint SubdivisionLevel;
public Displacement( uint level )
{
SubdivisionLevel = level;
}
public uint GetPartVertexCount()
{
// count at subdivision level 1
uint count = 4;
uint size = 2;
for ( uint i = 1; i < SubdivisionLevel; i++ )
{
size = ( size * 2 - 1 );
count = size * size;
}
return count;
}
public uint GetPartSizeInVertices()
{
// size at subdivision level 1
uint size = 2;
for ( uint i = 1; i < SubdivisionLevel; i++ )
{
size = size * 2 - 1;
}
return size;
}
public uint GetTotalVertexCount()
{
return GetPartVertexCount() * 4;
}
public uint GetSizeInPixels()
{
// size at subdivision level 1
uint size = 3;
for ( uint i = 1; i < SubdivisionLevel; i++ )
{
size = size * 2 - 1;
}
return size;
}
public List<uint> GetPixelIndices( uint x, uint y )
{
uint max = GetSizeInPixels() - 1;
if ( x > max || y > max )
throw new InvalidOperationException();
List<uint> parts = GetPixelParts(x, y);
List<uint> indices = new List<uint>();
foreach ( var part in parts )
{
indices.Add( GetPartPixelIndex( part, x, y ) );
}
return indices;
}
public uint GetPartPixelIndex( uint part, uint x, uint y )
{
// 0 indexed size
uint partSize = GetSizeInPixels() / 2;
uint minX, maxX, minY, maxY;
Tuple<int, int> rowDirection;
Tuple<int, int> columnDirection;
Tuple<int, int> indexPosition;
// Part order
// 2 - 1
// | |
// 3 - 0
switch ( part )
{
case 3:
minX = 0;
minY = 0;
maxX = partSize;
maxY = partSize;
// --->
// x-->
rowDirection = new Tuple<int, int>( 1, 0 );
columnDirection = new Tuple<int, int>( 0, 1 );
indexPosition = new Tuple<int, int>( 0, 0 );
break;
case 2:
minX = 0;
minY = partSize;
maxX = partSize;
maxY = partSize * 2;
// x |
// | |
// v v
rowDirection = new Tuple<int, int>( 0, -1 );
columnDirection = new Tuple<int, int>( 1, 0 );
indexPosition = new Tuple<int, int>( 0, ( int )partSize * 2 );
break;
case 1:
minX = partSize;
minY = partSize;
maxX = partSize * 2;
maxY = partSize * 2;
// <--x
// <---
rowDirection = new Tuple<int, int>( -1, 0 );
columnDirection = new Tuple<int, int>( 0, -1 );
indexPosition = new Tuple<int, int>( ( int )partSize * 2, ( int )partSize * 2 );
break;
case 0:
minX = partSize;
minY = 0;
maxX = partSize * 2;
maxY = partSize;
// ^ ^
// | |
// | x
rowDirection = new Tuple<int, int>( 0, 1 );
columnDirection = new Tuple<int, int>( -1, 0 );
indexPosition = new Tuple<int, int>( ( int )partSize * 2, 0 );
break;
default:
throw new InvalidOperationException();
}
if ( x < minX || y < minY || x > maxX || y > maxY )
throw new InvalidOperationException();
uint index = GetPartVertexCount() * part;
uint maxIndex = index + GetPartVertexCount() - 1;
uint minIndex = index;
while (
indexPosition.Item1 >= minX &&
indexPosition.Item1 <= maxX &&
indexPosition.Item2 >= minY &&
indexPosition.Item2 <= maxY &&
index <= maxIndex
)
{
if ( indexPosition.Item1 == x && indexPosition.Item2 == y )
{
return index;
}
if ( ( index + 1 ) % ( partSize + 1 ) == 0 && index > minIndex )
{
// new column
indexPosition = new Tuple<int, int>(
indexPosition.Item1 + columnDirection.Item1 - rowDirection.Item1 * ( int )partSize,
indexPosition.Item2 + columnDirection.Item2 - rowDirection.Item2 * ( int )partSize
);
}
else
{
// advance row
indexPosition = new Tuple<int, int>(
indexPosition.Item1 + rowDirection.Item1,
indexPosition.Item2 + rowDirection.Item2
);
}
index++;
}
throw new InvalidOperationException();
}
public List<uint> GetPixelParts( uint x, uint y )
{
uint max = GetSizeInPixels() - 1;
if ( x > max || y > max )
throw new InvalidOperationException();
// Part order
// 2 - 1
// | |
// 3 - 0
List<uint> parts = new List<uint>();
uint partSize = max / 2;
if ( x <= partSize && y <= partSize )
{
parts.Add( 3 );
}
if ( x <= partSize && y >= partSize )
{
parts.Add( 2 );
}
if ( x >= partSize && y >= partSize )
{
parts.Add( 1 );
}
if ( x >= partSize && y <= partSize )
{
parts.Add( 0 );
}
return parts;
}
}
}