public long GetHeight(int mapIndex, Vector2d position)
{
if (mapIndex >= Maps.Length)
{
return(this.HeightBounds.x);
}
HeightMap map = Maps [mapIndex];
long normX = (position.x - this._bottomLeft.x).Div(Interval);
long normY = (position.y - this._bottomLeft.y).Div(Interval);
int gridX = FixedMath.ToInt(normX);
int gridY = FixedMath.ToInt(normY);
long fractionX = (normX - FixedMath.Create(gridX));
long fractionY = (normY - FixedMath.Create(gridY));
long baseHeight = map.GetHeight(gridX, gridY);
int nextX = Mathf.Clamp(gridX + 1, 0, map.Map.Width);
int nextY = Mathf.Clamp(gridY + 1, 0, map.Map.Height);
//bilinear lerp
long h1 = FixedMath.Lerp(baseHeight, map.GetHeight(nextX, gridY), fractionX);
long h2 = FixedMath.Lerp(map.GetHeight(gridX, nextY), map.GetHeight(nextX, nextY), fractionX);
return(FixedMath.Lerp(h1, h2, fractionY) + this.BonusHeight);
}
