public static decimal[,] Get(decimal[,] resultArray, int cellsPerUnitSquare, GameComponents.RNG rng, decimal persistence = 1m)
{
int width = resultArray.GetLength(0);
int height = resultArray.GetLength(1);
int vectorWidth = (width / cellsPerUnitSquare) + 2; // make sure we have at least enough vectors for all 4 corners
int vectorHeight = (height / cellsPerUnitSquare) + 2;
Point[,] vectors = new Point[vectorWidth, vectorHeight];
for (int vx = 0; vx < vectorWidth; ++vx)
{
for (int vy = 0; vy < vectorHeight; ++vy)
{
int px = rng.GetNext(201) - 100; // store vectors as hundredths, positive or negative
int py = rng.GetNext(201) - 100;
vectors[vx, vy] = new Point(px, py);
}
}
decimal distBetweenMidpoints = 1m / (decimal)cellsPerUnitSquare;
for (int x = 0; x < width; ++x)
{
for (int y = 0; y < height; ++y)
{
// first find gradient vectors:
int sourceX = x / cellsPerUnitSquare;
int sourceY = y / cellsPerUnitSquare;
// also find where this x,y is within the containing square:
int xInCell = x % cellsPerUnitSquare;
int yInCell = y % cellsPerUnitSquare;
decimal xVector0 = (distBetweenMidpoints * 0.5m) + xInCell * distBetweenMidpoints;
decimal yVector0 = (distBetweenMidpoints * 0.5m) + yInCell * distBetweenMidpoints;
decimal xVector1 = 1m - xVector0;
decimal yVector1 = 1m - yVector0;
decimal xGradientx0y0 = vectors[sourceX, sourceY].X / 100m;
decimal xGradientx1y0 = vectors[sourceX + 1, sourceY].X / 100m;
decimal xGradientx0y1 = vectors[sourceX, sourceY + 1].X / 100m;
decimal xGradientx1y1 = vectors[sourceX + 1, sourceY + 1].X / 100m;
decimal yGradientx0y0 = vectors[sourceX, sourceY].Y / 100m;
decimal yGradientx1y0 = vectors[sourceX + 1, sourceY].Y / 100m;
decimal yGradientx0y1 = vectors[sourceX, sourceY + 1].Y / 100m;
decimal yGradientx1y1 = vectors[sourceX + 1, sourceY + 1].Y / 100m;
decimal x0y0Dot = xGradientx0y0 * xVector0 + yGradientx0y0 * yVector0;
decimal x1y0Dot = xGradientx1y0 * xVector1 + yGradientx1y0 * yVector0;
decimal x0y1Dot = xGradientx0y1 * xVector0 + yGradientx0y1 * yVector1;
decimal x1y1Dot = xGradientx1y1 * xVector1 + yGradientx1y1 * yVector1;
decimal lerpX0 = Lerp(x0y0Dot, x1y0Dot, xVector0);
decimal lerpX1 = Lerp(x0y1Dot, x1y1Dot, xVector0);
decimal lerpFinal = Lerp(lerpX0, lerpX1, yVector0);
resultArray[x, y] += lerpFinal * 256m * persistence;
}
}
return(resultArray);
}
public static decimal[,] Get(int width, int height, int cellsPerUnitSquare, GameComponents.RNG rng)
{
decimal[,] result = new decimal[width, height];
return(Get(result, cellsPerUnitSquare, rng));
}
