/// <summary>
/// Sample the Perlin Noise Map at a coordinate (x,y,z).
/// </summary>
/// <param name="x">Coordinate from which to sample the Perlin Noise Map.</param>
/// <param name="y">Coordinate from which to sample the Perlin Noise Map.</param>
/// <param name="z">Coordinate from which to sample the Perlin Noise Map.</param>
/// <returns>The Perlin Noise Map value at (x,y,z).</returns>
public static double GetNoise(double x, double y, double z)
{
int xindex = (int)Math.Floor(x);
int yindex = (int)Math.Floor(y);
int zindex = (int)Math.Floor(z);
// Logival bitwise AND caps index values at 255.
xindex = xindex & 255;
yindex = yindex & 255;
zindex = zindex & 255;
double dx = x - (int)x;
double dy = y - (int)y;
double dz = z - (int)z;
double u = PerlinFade(dx);
double v = PerlinFade(dy);
double w = PerlinFade(dz);
int m000 = p[p[p[xindex] + yindex] + zindex];
int m010 = p[p[p[xindex] + yindex + 1] + zindex];
int m100 = p[p[p[xindex + 1] + yindex] + zindex];
int m110 = p[p[p[xindex + 1] + yindex + 1] + zindex];
int m001 = p[p[p[xindex] + yindex] + zindex + 1];
int m011 = p[p[p[xindex] + yindex + 1] + zindex + 1];
int m101 = p[p[p[xindex + 1] + yindex] + zindex + 1];
int m111 = p[p[p[xindex + 1] + yindex + 1] + zindex + 1];
double x1 = JMathUtils.Lerp(Grad(m000, dx, dy, dz),
Grad(m100, dx - 1, dy, dz),
u
);
double x2 = JMathUtils.Lerp(Grad(m010, dx, dy - 1, dz),
Grad(m110, dx - 1, dy - 1, dz),
u
);
double y1 = JMathUtils.Lerp(x1,
x2,
v
);
x1 = JMathUtils.Lerp(Grad(m001, dx, dy, dz - 1),
Grad(m101, dx - 1, dy, dz - 1),
u
);
x2 = JMathUtils.Lerp(Grad(m011, dx, dy - 1, dz - 1),
Grad(m111, dx - 1, dy - 1, dz - 1),
u
);
double y2 = JMathUtils.Lerp(x1,
x2,
v
);
return((JMathUtils.Lerp(y1, y2, w) + 1) / 2);
}
/// <summary>
/// Create a JMousePicker instance. JMousePicker will project a 2D screen coordinate into a 3D unit vector within the world.
/// It can determine intersection with terrain as well as check for intersection with a JBoundingSphere.
/// </summary>
/// <param name="camera">The JCamera entity.</param>
/// <param name="projectionMatrix">The JMasterRenderers Projection Matrix based off of the JCameras properties.</param>
/// <param name="terrain">The JTerrain the Mouse Ray will intersect with.</param>
/// <param name="gameWindow">The active JGameWindow. We need this to get it's height and width.</param>
public JMousePicker(JCamera camera, Matrix4 projectionMatrix, JPerlinTerrain terrain, JGameWindow gameWindow)
{
Camera = camera;
ProjectionMatrix = projectionMatrix;
ViewMatrix = JMathUtils.createViewMatrix(camera);
Terrain = terrain;
GameWindow = gameWindow;
}
/// <summary>
/// Update CurrentRay each frame from the current 2D mouse coordinate. Also updates CurrentTerrainPoint reflecting CurrentRays intersection with
/// Terrain.
/// </summary>
public void Update()
{
ViewMatrix = JMathUtils.createViewMatrix(Camera);
CurrentRay = CalculateMouseRay();
if (IntersectionInRange(0, JConfig.MOUSE_PICKER_RAY_RANGE, CurrentRay))
{
CurrentTerrainPoint = BinarySearch(0, 0, JConfig.MOUSE_PICKER_RAY_RANGE, CurrentRay);
}
else
{
CurrentTerrainPoint = new Vector3(0, 0, 0);
}
}