private void GenerateDensityMap(float[,,] densityMap, int xOffset, int yOffset, int zOffset, GeneratorSettings settings)
{
_depthNoise.Noise(
_depthMap,
new Vector3(xOffset + 0.1f, 0.0f, zOffset + 0.1f),
new Vector3(settings.DepthNoiseScaleX, 1.0f, settings.DepthNoiseScaleZ));
float coordinateScale = settings.CoordinateScale;
float heightScale = settings.HeightScale;
// 生成3个5*5*33的噪声
_mainNoise.Noise(
_mainNoiseMap,
new Vector3(xOffset, yOffset, zOffset),
new Vector3(
coordinateScale / settings.MainNoiseScaleX,
heightScale / settings.MainNoiseScaleY,
coordinateScale / settings.MainNoiseScaleZ));
_minNoise.Noise(
_minLimitMap,
new Vector3(xOffset, yOffset, zOffset),
new Vector3(
coordinateScale,
heightScale,
coordinateScale));
_maxNoise.Noise(
_maxLimitMap,
new Vector3(xOffset, yOffset, zOffset),
new Vector3(
coordinateScale,
heightScale,
coordinateScale));
// chunk遍历
for (int x1 = 0; x1 < 5; ++x1)
{
for (int z1 = 0; z1 < 5; ++z1)
{
float scale = 0.0F;
float groundYOffset = 0.0F;
float totalWeight = 0.0F;
// 中心点生物群系
Biome centerBiome = _biomesForGeneration[z1 + 2, x1 + 2];
// 求scale和groundYOffset的加权平均值
for (int x2 = 0; x2 < 5; ++x2)
{
for (int z2 = 0; z2 < 5; ++z2)
{
Biome biome = _biomesForGeneration[z1 + z2, x1 + x2];
float curGroundYOffset = settings.BiomeDepthOffSet + biome.GetBaseHeight() * settings.BiomeDepthWeight; // biomeDepthOffSet=0
float curScale = settings.BiomeScaleOffset + biome.GetHeightVariation() * settings.BiomeScaleWeight; // biomeScaleOffset=0
// parabolicField为 10 / √(该点到中心点的距离^2 + 0.2)
float weight = _biomeWeights[z2, x2] / (curGroundYOffset + 2.0F);
if (biome.GetBaseHeight() > centerBiome.GetBaseHeight())
{
weight /= 2.0F;
}
scale += curScale * weight;
groundYOffset += curGroundYOffset * weight;
totalWeight += weight;
}
}
scale = scale / totalWeight;
groundYOffset = groundYOffset / totalWeight;
scale = scale * 0.9F + 0.1F;
groundYOffset = (groundYOffset * 4.0F - 1.0F) / 8.0F;
// 取一个-0.36~0.125的随机数，这个随机数决定了起伏的地表
float random = (_depthMap[x1, 0, z1] - 0.5F) * 2 / 8000.0F;
if (random < 0.0F)
{
random = -random * 0.3F;
}
random = random * 3.0F - 2.0F;
if (random < 0.0)
{
random = random / 2.0F;
if (random < -1.0)
{
random = -1.0F;
}
random = random / 1.4F;
random = random / 2.0F;
}
else
{
if (random > 1.0F)
{
random = 1.0F;
}
random = random / 8.0F;
}
float groundYOffset1 = groundYOffset;
float scale1 = scale;
// groundYOffset有-0.072~0.025的变动量
groundYOffset1 = groundYOffset1 + random * 0.2F;
groundYOffset1 = groundYOffset1 * settings.BaseSize / 8.0F;
// 这个是大概的地面y坐标
float groundY = settings.BaseSize + groundYOffset1 * 4.0F; // baseSize=8.5，应该代表了平均地表高度68
// 注意这个y*8才是最终的y坐标
for (int y = 0; y < 33; ++y)
{
// result偏移量，这个是负数则趋向固体，是正数则趋向液体和空气
float offset = (y - groundY) * settings.StretchY * 128.0F / 256.0F / scale1; // scale大概在0.1~0.2这样...
if (offset < 0.0F)
{
offset *= 4.0F;
}
// 并不保证lowerLimit < upperLimit，不过没有影响
float lowerLimit = (_minLimitMap[x1, y, z1] - 0.5F) * 160000 / settings.LowerLimitScale; // lowerLimitScale=512
float upperLimit = (_maxLimitMap[x1, y, z1] - 0.5F) * 160000 / settings.UpperLimitScale; // upperLimitScale=512
float t = ((_mainNoiseMap[x1, y, z1] - 0.5F) * 160000 / 10.0F + 1.0F) / 2.0F;
// 这个函数t < 0则取lowerLimit，t > 1则取upperLimit，否则以t为参数在上下限间线性插值
float result = MathHelper.DenormalizeClamp(lowerLimit, upperLimit, t) - offset;
// y = 30~32
if (y > 29)
{
// 在原result和-10之间线性插值，这样y > 240的方块就会越来越少，最后全变成空气
float t2 = (float)(y - 29) / 3.0F;
result = result * (1.0F - t2) + -10.0F * t2;
}
_densityMap[x1, y, z1] = (float)result;
}
}
}
densityMap = _densityMap;
}
