/// <summary>
/// Generate a float[mapWidth,mapHeight] containing values in the range [0,1] based on PerlinNoise algorithm.
/// </summary>
/// <param name="mapWidth"></param>
/// <param name="mapHeight"></param>
/// <param name="scale"></param>
/// <param name="octaves">The number of octives. Must be greater than 0.</param>
/// <param name="persistance">A value, in the range 0 to 1, commonly 0.5.</param>
/// <param name="lacunarity">A value, greater than 1, commonly 2.</param>
/// <returns>A float array of "randomly" distributed values.</returns>
public static float[,] GenerateNoiseMap(int mapWidth, int mapHeight, float scale, int octaves, float persistance, float lacunarity)
{
float[,] noiseMap = new float[mapWidth, mapHeight];
float maxNoiseHeight = float.MinValue;
float minNoiseHeight = float.MaxValue;
if (scale <= 0)
{
scale = 0.0001f;
}
for (int y = 0; y < mapHeight; y++)
{
for (int x = 0; x < mapWidth; x++)
{
float amplitude = 1;
float frequency = 1;
float noiseHeight = 0;
for (int i = 0; i < octaves; i++)
{
float sampleX = (x / scale) * frequency;
float sampleY = (y / scale) * frequency;
float perlinValue = (float)JPerlinNoise.GetNoise((double)sampleX, (double)sampleY, (double)1.0f) * 2 - 1;
noiseHeight += perlinValue * amplitude;
// Amplitude decreases each octive.
amplitude *= persistance;
// Frequency increases each octive.
frequency *= lacunarity;
}
// Track the minimum and maximum values within noiseMap.
if (noiseHeight > maxNoiseHeight)
{
maxNoiseHeight = noiseHeight;
}
else if (noiseHeight < minNoiseHeight)
{
minNoiseHeight = noiseHeight;
}
noiseMap[x, y] = noiseHeight;
}
}
// Map the noiseMap values to the range [0,1].
for (int y = 0; y < mapHeight; y++)
{
for (int x = 0; x < mapWidth; x++)
{
noiseMap[x, y] = JMathUtils.InvLerp(minNoiseHeight, maxNoiseHeight, noiseMap[x, y]);
}
}
return(noiseMap);
}
/// <summary>
/// Use an offset to sample JPerlinNoise at a random location rather than a consistent location. Not working quite right yet.
/// </summary>
/// <param name="mapWidth"></param>
/// <param name="mapHeight"></param>
/// <param name="seed"></param>
/// <param name="scale"></param>
/// <param name="octaves">The number of octives. Must be greater than 0.</param>
/// <param name="persistance">A value, in the range 0 to 1, commonly 0.5.</param>
/// <param name="lacunarity">A value, greater than 1, commonly 2.</param>
/// <returns></returns>
public static float[,] GenerateNoiseMap(int mapWidth, int mapHeight, int seed, float scale, int octaves, float persistance, float lacunarity)
{
float[,] noiseMap = new float[mapWidth, mapHeight];
float maxNoiseHeight = float.MinValue;
float minNoiseHeight = float.MaxValue;
Random rand = new Random(seed);
Vector2[] octaveOffsets = new Vector2[octaves];
for (int i = 0; i < octaves; i++)
{
float offsetX = rand.Next(-5, 5) / scale;
float offsetY = rand.Next(-5, 5) / scale;
octaveOffsets[i] = new Vector2(offsetX, offsetY);
}
if (scale <= 0)
{
scale = 0.0001f;
}
for (int y = 0; y < mapHeight; y++)
{
for (int x = 0; x < mapWidth; x++)
{
float amplitude = 1;
float frequency = 1;
float noiseHeight = 0;
for (int i = 0; i < octaves; i++)
{
float sampleX = (x / scale) * frequency + octaveOffsets[i].X;
float sampleY = (y / scale) * frequency + octaveOffsets[i].Y;
float perlinValue = (float)JPerlinNoise.GetNoise((double)sampleX, (double)sampleY, (double)1.0f) * 2 - 1;
noiseHeight += perlinValue * amplitude;
// Amplitude decreases each octive.
amplitude *= persistance;
// Frequency increases each octive.
frequency *= lacunarity;
}
// Track the minimum and maximum values with noiseMap.
if (noiseHeight > maxNoiseHeight)
{
maxNoiseHeight = noiseHeight;
}
else if (noiseHeight < minNoiseHeight)
{
minNoiseHeight = noiseHeight;
}
noiseMap[x, y] = noiseHeight;
}
}
for (int y = 0; y < mapHeight; y++)
{
for (int x = 0; x < mapWidth; x++)
{
noiseMap[x, y] = JMathUtils.InvLerp(minNoiseHeight, maxNoiseHeight, noiseMap[x, y]);
}
}
return(noiseMap);
}
