using System.Collections.Generic;
using FarseerPhysics.Collision;
using FarseerPhysics.Common.Decomposition;
using FarseerPhysics.Common.PolygonManipulation;
using FarseerPhysics.Dynamics;
using FarseerPhysics.Factories;
using Microsoft.Xna.Framework;
namespace FarseerPhysics.Common.TextureTools
{
///
/// Simple class to maintain a terrain. It can keep track
///
public class Terrain
{
///
/// World to manage terrain in.
///
public World World;
///
/// Center of terrain in world units.
///
public Vector2 Center;
///
/// Width of terrain in world units.
///
public float Width;
///
/// Height of terrain in world units.
///
public float Height;
///
/// Points per each world unit used to define the terrain in the point cloud.
///
public int PointsPerUnit;
///
/// Points per cell.
///
public int CellSize;
///
/// Points per sub cell.
///
public int SubCellSize;
///
/// Number of iterations to perform in the Marching Squares algorithm.
/// Note: More then 3 has almost no effect on quality.
///
public int Iterations = 2;
///
/// Decomposer to use when regenerating terrain. Can be changed on the fly without consequence.
/// Note: Some decomposerers are unstable.
///
public TriangulationAlgorithm Decomposer;
///
/// Point cloud defining the terrain.
///
private sbyte[,] _terrainMap;
///
/// Generated bodies.
///
private List[,] _bodyMap;
private float _localWidth;
private float _localHeight;
private int _xnum;
private int _ynum;
private AABB _dirtyArea;
private Vector2 _topLeft;
///
/// Creates a new terrain.
///
/// The World
/// The area of the terrain.
public Terrain(World world, AABB area)
{
World = world;
Width = area.Width;
Height = area.Height;
Center = area.Center;
}
///
/// Creates a new terrain
///
/// The World
/// The position (center) of the terrain.
/// The width of the terrain.
/// The height of the terrain.
public Terrain(World world, Vector2 position, float width, float height)
{
World = world;
Width = width;
Height = height;
Center = position;
}
///
/// Initialize the terrain for use.
///
public void Initialize()
{
// find top left of terrain in world space
_topLeft = new Vector2(Center.X - (Width * 0.5f), Center.Y - (-Height * 0.5f));
// convert the terrains size to a point cloud size
_localWidth = Width * PointsPerUnit;
_localHeight = Height * PointsPerUnit;
_terrainMap = new sbyte[(int)_localWidth + 1, (int)_localHeight + 1];
for (int x = 0; x < _localWidth; x++)
{
for (int y = 0; y < _localHeight; y++)
{
_terrainMap[x, y] = 1;
}
}
_xnum = (int)(_localWidth / CellSize);
_ynum = (int)(_localHeight / CellSize);
_bodyMap = new List[_xnum, _ynum];
// make sure to mark the dirty area to an infinitely small box
_dirtyArea = new AABB(new Vector2(float.MaxValue, float.MaxValue), new Vector2(float.MinValue, float.MinValue));
}
///
/// Apply the specified texture data to the terrain.
///
///
///
public void ApplyData(sbyte[,] data, Vector2 offset = default(Vector2))
{
for (int x = 0; x < data.GetUpperBound(0); x++)
{
for (int y = 0; y < data.GetUpperBound(1); y++)
{
if (x + offset.X >= 0 && x + offset.X < _localWidth && y + offset.Y >= 0 && y + offset.Y < _localHeight)
{
_terrainMap[(int)(x + offset.X), (int)(y + offset.Y)] = data[x, y];
}
}
}
RemoveOldData(0, _xnum, 0, _ynum);
}
///
/// Modify a single point in the terrain.
///
/// World location to modify. Automatically clipped.
/// -1 = inside terrain, 1 = outside terrain
public void ModifyTerrain(Vector2 location, sbyte value)
{
// find local position
// make position local to map space
Vector2 p = location - _topLeft;
// find map position for each axis
p.X = p.X * _localWidth / Width;
p.Y = p.Y * -_localHeight / Height;
if (p.X >= 0 && p.X < _localWidth && p.Y >= 0 && p.Y < _localHeight)
{
_terrainMap[(int)p.X, (int)p.Y] = value;
// expand dirty area
if (p.X < _dirtyArea.LowerBound.X) _dirtyArea.LowerBound.X = p.X;
if (p.X > _dirtyArea.UpperBound.X) _dirtyArea.UpperBound.X = p.X;
if (p.Y < _dirtyArea.LowerBound.Y) _dirtyArea.LowerBound.Y = p.Y;
if (p.Y > _dirtyArea.UpperBound.Y) _dirtyArea.UpperBound.Y = p.Y;
}
}
///
/// Regenerate the terrain.
///
public void RegenerateTerrain()
{
//iterate effected cells
int xStart = (int)(_dirtyArea.LowerBound.X / CellSize);
if (xStart < 0) xStart = 0;
int xEnd = (int)(_dirtyArea.UpperBound.X / CellSize) + 1;
if (xEnd > _xnum) xEnd = _xnum;
int yStart = (int)(_dirtyArea.LowerBound.Y / CellSize);
if (yStart < 0) yStart = 0;
int yEnd = (int)(_dirtyArea.UpperBound.Y / CellSize) + 1;
if (yEnd > _ynum) yEnd = _ynum;
RemoveOldData(xStart, xEnd, yStart, yEnd);
_dirtyArea = new AABB(new Vector2(float.MaxValue, float.MaxValue), new Vector2(float.MinValue, float.MinValue));
}
private void RemoveOldData(int xStart, int xEnd, int yStart, int yEnd)
{
for (int x = xStart; x < xEnd; x++)
{
for (int y = yStart; y < yEnd; y++)
{
//remove old terrain object at grid cell
if (_bodyMap[x, y] != null)
{
for (int i = 0; i < _bodyMap[x, y].Count; i++)
{
World.RemoveBody(_bodyMap[x, y][i]);
}
}
_bodyMap[x, y] = null;
//generate new one
GenerateTerrain(x, y);
}
}
}
private void GenerateTerrain(int gx, int gy)
{
float ax = gx * CellSize;
float ay = gy * CellSize;
List polys = MarchingSquares.DetectSquares(new AABB(new Vector2(ax, ay), new Vector2(ax + CellSize, ay + CellSize)), SubCellSize, SubCellSize, _terrainMap, Iterations, true);
if (polys.Count == 0) return;
_bodyMap[gx, gy] = new List();
// create the scale vector
Vector2 scale = new Vector2(1f / PointsPerUnit, 1f / -PointsPerUnit);
// create physics object for this grid cell
foreach (Vertices item in polys)
{
// does this need to be negative?
item.Scale(ref scale);
item.Translate(ref _topLeft);
Vertices simplified = SimplifyTools.CollinearSimplify(item);
List decompPolys = Triangulate.ConvexPartition(simplified, Decomposer);
foreach (Vertices poly in decompPolys)
{
if (poly.Count > 2)
_bodyMap[gx, gy].Add(BodyFactory.CreatePolygon(World, poly, 1));
}
}
}
}
}