/// <summary>
/// Generates a index for a triangle soup quad with the specified shape
/// </summary>
/// <param name="lod">Level of detail</param>
/// <param name="bufferShape">Buffer shape</param>
/// <param name="triangles">Triangle count</param>
/// <returns>Returns the generated index list</returns>
public static uint[] GenerateIndices(LevelOfDetail lod, IndexBufferShapes bufferShape, int triangles)
{
uint offset = (uint)lod;
uint fullSide = (uint)Math.Sqrt(triangles / 2f);
int tris = triangles / (int)Math.Pow(offset, 2);
int nodes = tris / 2;
uint side = (uint)Math.Sqrt(nodes);
uint sideLoss = side / 2;
bool topSide =
bufferShape == IndexBufferShapes.CornerTopLeft ||
bufferShape == IndexBufferShapes.CornerTopRight ||
bufferShape == IndexBufferShapes.SideTop;
bool bottomSide =
bufferShape == IndexBufferShapes.CornerBottomLeft ||
bufferShape == IndexBufferShapes.CornerBottomRight ||
bufferShape == IndexBufferShapes.SideBottom;
bool leftSide =
bufferShape == IndexBufferShapes.CornerBottomLeft ||
bufferShape == IndexBufferShapes.CornerTopLeft ||
bufferShape == IndexBufferShapes.SideLeft;
bool rightSide =
bufferShape == IndexBufferShapes.CornerBottomRight ||
bufferShape == IndexBufferShapes.CornerTopRight ||
bufferShape == IndexBufferShapes.SideRight;
uint totalTriangles = (uint)tris;
if (topSide)
{
totalTriangles -= sideLoss;
}
if (bottomSide)
{
totalTriangles -= sideLoss;
}
if (leftSide)
{
totalTriangles -= sideLoss;
}
if (rightSide)
{
totalTriangles -= sideLoss;
}
List <uint> indices = new List <uint>((int)totalTriangles * 3);
for (uint y = 1; y < side; y += 2)
{
for (uint x = 1; x < side; x += 2)
{
uint indexPRow = (((y - 1) * offset) * (fullSide + 1)) + (x * offset);
uint indexCRow = (((y + 0) * offset) * (fullSide + 1)) + (x * offset);
uint indexNRow = (((y + 1) * offset) * (fullSide + 1)) + (x * offset);
bool firstRow = y == 1;
bool lastRow = y == side - 1;
bool firstColumn = x == 1;
bool lastColumn = x == side - 1;
//Top side
var top = ComputeTopSide(firstRow, topSide, offset, indexPRow, indexCRow);
//Bottom side
var bottom = ComputeBottomSide(lastRow, bottomSide, offset, indexCRow, indexNRow);
//Left side
var left = ComputeLeftSide(firstColumn, leftSide, offset, indexPRow, indexCRow, indexNRow);
//Right side
var right = ComputeRightSide(lastColumn, rightSide, offset, indexPRow, indexCRow, indexNRow);
indices.AddRange(top);
indices.AddRange(bottom);
indices.AddRange(left);
indices.AddRange(right);
}
}
return(indices.ToArray());
}
/// <summary>
/// Generates a index for a triangle soup quad with the specified shape
/// </summary>
/// <param name="bufferShape">Buffer shape</param>
/// <param name="triangles">Triangle count</param>
/// <returns>Returns the generated index list</returns>
public static uint[] GenerateIndices(IndexBufferShapes bufferShape, int triangles)
{
return(GenerateIndices(LevelOfDetail.High, bufferShape, triangles));
}
