aboutsummaryrefslogtreecommitdiffstatshomepage
path: root/Common/OpenSim.Framework/HeightMapGenHills.cs
blob: 9777b82701c6a16ebc3ca464c57ac2302d90d6ad (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
/*
* Copyright (c) Contributors, http://www.openmetaverse.org/
* See CONTRIBUTORS.TXT for a full list of copyright holders.
*
* 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 OpenSim Project 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 THE DEVELOPERS ``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 THE CONTRIBUTORS 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.Framework.Terrain
{
    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;
        }
    }
}