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/*
* Copyright (c) OpenSim project, http://sim.opensecondlife.org/
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the <organization> nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY <copyright holder> ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL <copyright holder> BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
using System;
namespace OpenSim
{
public class HeightmapGenHills
{
private Random Rand = new Random();
private int NumHills;
private float HillMin;
private float HillMax;
private bool Island;
private float[] heightmap;
public float[] GenerateHeightmap(int numHills, float hillMin, float hillMax, bool island)
{
NumHills = numHills;
HillMin = hillMin;
HillMax = hillMax;
Island = island;
heightmap = new float[256 * 256];
for (int i = 0; i < numHills; i++)
{
AddHill();
}
Normalize();
return heightmap;
}
private void AddHill()
{
float x, y;
float radius = RandomRange(HillMin, HillMax);
if (Island)
{
// Which direction from the center of the map the hill is placed
float theta = RandomRange(0, 6.28f);
// How far from the center of the map to place the hill. The radius
// is subtracted from the range to prevent any part of the hill from
// reaching the edge of the map
float distance = RandomRange(radius / 2.0f, 128.0f - radius);
x = 128.0f + (float)Math.Cos(theta) * distance;
y = 128.0f + (float)Math.Sin(theta) * distance;
}
else
{
x = RandomRange(-radius, 256.0f + radius);
y = RandomRange(-radius, 256.0f + radius);
}
float radiusSq = radius * radius;
float distSq;
float height;
int xMin = (int)(x - radius) - 1;
int xMax = (int)(x + radius) + 1;
if (xMin < 0) xMin = 0;
if (xMax > 255) xMax = 255;
int yMin = (int)(y - radius) - 1;
int yMax = (int)(y + radius) + 1;
if (yMin < 0) yMin = 0;
if (yMax > 255) yMax = 255;
// Loop through each affected cell and determine the height at that point
for (int v = yMin; v <= yMax; ++v)
{
float fv = (float)v;
for (int h = xMin; h <= xMax; ++h)
{
float fh = (float)h;
// Determine how far from the center of this hill this point is
distSq = (x - fh) * (x - fh) + (y - fv) * (y - fv);
height = radiusSq - distSq;
// Don't add negative hill values
if (height > 0.0f) heightmap[h + v * 256] += height;
}
}
}
private void Normalize()
{
float min = heightmap[0];
float max = heightmap[0];
for (int x = 0; x < 256; x++)
{
for (int y = 0; y < 256; y++)
{
if (heightmap[x + y * 256] < min) min = heightmap[x + y * 256];
if (heightmap[x + y * 256] > max) max = heightmap[x + y * 256];
}
}
// Avoid a rare divide by zero
if (min != max)
{
for (int x = 0; x < 256; x++)
{
for (int y = 0; y < 256; y++)
{
heightmap[x + y * 256] = ((heightmap[x + y * 256] - min) / (max - min)) * (HillMax - HillMin);
}
}
}
}
private float RandomRange(float min, float max)
{
return (float)Rand.NextDouble() * (max - min) + min;
}
}
}
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