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using Microsoft.Xna.Framework;
namespace MonoGame.Extended.Tiled
{
public static class TiledMapHelper
{
// 4 vertices per tile
public const int VerticesPerTile = 4;
// 2 triangles per tile (mesh), with each triangle indexing 3 out of 4 vertices, so 6 vertices
public const int IndicesPerTile = 6;
// by using ushort type for indices we are limited to indexing vertices from 0 to 65535
// this limits us on how many vertices can fit inside a single vertex buffer (65536 vertices)
public const int MaximumVerticesPerModel = ushort.MaxValue + 1;
// and thus, we know how many tiles we can fit inside a vertex or index buffer (16384 tiles)
public const int MaximumTilesPerGeometryContent = MaximumVerticesPerModel / VerticesPerTile;
// and thus, we also know the maximum number of indices we can fit inside a single index buffer (98304 indices)
public const int MaximumIndicesPerModel = MaximumTilesPerGeometryContent * IndicesPerTile;
// these optimal maximum numbers of course are not considering texture bindings which would practically lower the actual number of tiles per vertex / index buffer
// thus, the reason why it is a good to have ONE giant tileset (at least per layer)
internal static Rectangle GetTileSourceRectangle(int localTileIdentifier, int tileWidth, int tileHeight, int columns, int margin, int spacing)
{
var x = margin + localTileIdentifier % columns * (tileWidth + spacing);
var y = margin + localTileIdentifier / columns * (tileHeight + spacing);
return new Rectangle(x, y, tileWidth, tileHeight);
}
internal static Point2 GetOrthogonalPosition(int tileX, int tileY, int tileWidth, int tileHeight)
{
var x = tileX * tileWidth;
var y = tileY * tileHeight;
return new Vector2(x, y);
}
internal static Point2 GetIsometricPosition(int tileX, int tileY, int tileWidth, int tileHeight)
{
// You can think of an isometric Tiled map as a regular orthogonal map that is rotated -45 degrees
// i.e.: the origin (0, 0) is the top tile of the diamond grid;
// (mapWidth, 0) is the far right tile of the diamond grid
// (0, mapHeight) is the far left tile of the diamond grid
// (mapWidth, mapHeight) is the bottom tile of the diamond grid
var halfTileWidth = tileWidth * 0.5f;
var halfTileHeight = tileHeight * 0.5f;
// -1 because we want the top the tile-diamond (top-center) to be the origin in tile space
var x = (tileX - tileY - 1) * halfTileWidth;
var y = (tileX + tileY) * halfTileHeight;
return new Vector2(x, y);
}
}
}
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