public float GetNoiseTiled(Vector2 vec)
{
var s = vec.X / _periodX;
var t = vec.Y / _periodY;
const float x1 = 0;
const float x2 = 1;
const float y1 = 0;
const float y2 = 1;
const float dx = x2 - x1;
const float dy = y2 - y1;
const float tau = (float)Math.TAU; //(float)Math.PI * 2;
const float dxTau = dx / tau;
const float dyTau = dy / tau;
var nx = x1 + (float)Math.Cos(s * tau) * dxTau;
var ny = y1 + (float)Math.Cos(t * tau) * dyTau;
var nz = x1 + (float)Math.Sin(s * tau) * dxTau;
var nw = y1 + (float)Math.Sin(t * tau) * dyTau;
return(GetNoise(nx, ny, nz, nw));
}
/// <summary>
/// Converts this angle to a unit direction vector.
/// </summary>
/// <returns>Unit Direction Vector</returns>
public Vector2 ToVec()
{
var x = Math.Cos(Theta);
var y = Math.Sin(Theta);
return(new Vector2((float)x, (float)y));
}
public static Matrix3 CreateRotation(Angle angle)
{
var cos = (float)Math.Cos(angle);
var sin = (float)Math.Sin(angle);
var result = Identity;
/* column major
* cos -sin 0
* sin cos 0
* 0 0 1
*/
result.R0C0 = cos;
result.R1C0 = sin;
result.R0C1 = -sin;
result.R1C1 = cos;
return(result);
}
/// <summary>
/// calculates the smallest AABB that will encompass the rotated box. The AABB is in local space.
/// </summary>
public Box2 CalcBoundingBox()
{
// https://stackoverflow.com/a/19830964
var(X0, Y0) = Box.BottomLeft;
var(X1, Y1) = Box.TopRight;
var Fi = Rotation.Theta;
var CX = (X0 + X1) / 2; //Center point
var CY = (Y0 + Y1) / 2;
var WX = (X1 - X0) / 2; //Half-width
var WY = (Y1 - Y0) / 2;
var SF = Math.Sin(Fi);
var CF = Math.Cos(Fi);
var NH = Math.Abs(WX * SF) + Math.Abs(WY * CF); //boundrect half-height
var NW = Math.Abs(WX * CF) + Math.Abs(WY * SF); //boundrect half-width
return(new Box2((float)(CX - NW), (float)(CY - NH), (float)(CX + NW), (float)(CY + NH))); //draw bound rectangle
}