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TerrainUtil.cs 4.9 KB

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  1. /*
  2. * Copyright (c) Contributors, http://opensimulator.org/
  3. * See CONTRIBUTORS.TXT for a full list of copyright holders.
  4. *
  5. * Redistribution and use in source and binary forms, with or without
  6. * modification, are permitted provided that the following conditions are met:
  7. * * Redistributions of source code must retain the above copyright
  8. * notice, this list of conditions and the following disclaimer.
  9. * * Redistributions in binary form must reproduce the above copyright
  10. * notice, this list of conditions and the following disclaimer in the
  11. * documentation and/or other materials provided with the distribution.
  12. * * Neither the name of the OpenSimulator Project nor the
  13. * names of its contributors may be used to endorse or promote products
  14. * derived from this software without specific prior written permission.
  15. *
  16. * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
  17. * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  18. * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  19. * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
  20. * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  21. * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  22. * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  23. * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24. * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  25. * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26. */
  27. using System;
  28. using OpenSim.Region.Framework.Interfaces;
  29. namespace OpenSim.Region.Framework.Scenes
  30. {
  31. public static class TerrainUtil
  32. {
  33. public static float SphericalFactor(float dx, float dy, float size)
  34. {
  35. float a = ((dx * dx) + (dy * dy))/ (size * size);
  36. if( a >= 1.0f)
  37. return 0;
  38. return 1.0f - a;
  39. }
  40. public static double GetBilinearInterpolate(double x, double y, ITerrainChannel map)
  41. {
  42. int w = map.Width;
  43. int h = map.Height;
  44. if (x > w - 2.0)
  45. x = w - 2.0;
  46. if (y > h - 2.0)
  47. y = h - 2.0;
  48. if (x < 0.0)
  49. x = 0.0;
  50. if (y < 0.0)
  51. y = 0.0;
  52. const int stepSize = 1;
  53. double h00 = map[(int) x, (int) y];
  54. double h10 = map[(int) x + stepSize, (int) y];
  55. double h01 = map[(int) x, (int) y + stepSize];
  56. double h11 = map[(int) x + stepSize, (int) y + stepSize];
  57. double a00 = h00;
  58. double a10 = h10 - h00;
  59. double a01 = h01 - h00;
  60. double a11 = h11 - h10 - h01 + h00;
  61. double partialx = x - (int) x;
  62. double partialy = y - (int) y;
  63. double hi = a00 + (a10 * partialx) + (a01 * partialy) + (a11 * partialx * partialy);
  64. return hi;
  65. }
  66. private static double Noise(double x, double y)
  67. {
  68. int n = (int) x + (int) (y * 749);
  69. n = (n << 13) ^ n;
  70. return (1.0 - ((n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff) / 1073741824.0);
  71. }
  72. private static double SmoothedNoise1(double x, double y)
  73. {
  74. double corners = (Noise(x - 1, y - 1) + Noise(x + 1, y - 1) + Noise(x - 1, y + 1) + Noise(x + 1, y + 1)) / 16;
  75. double sides = (Noise(x - 1, y) + Noise(x + 1, y) + Noise(x, y - 1) + Noise(x, y + 1)) / 8;
  76. double center = Noise(x, y) / 4;
  77. return corners + sides + center;
  78. }
  79. private static double Interpolate(double x, double y, double z)
  80. {
  81. return (x * (1.0 - z)) + (y * z);
  82. }
  83. public static double InterpolatedNoise(double x, double y)
  84. {
  85. int integer_X = (int) (x);
  86. double fractional_X = x - integer_X;
  87. int integer_Y = (int) y;
  88. double fractional_Y = y - integer_Y;
  89. double v1 = SmoothedNoise1(integer_X, integer_Y);
  90. double v2 = SmoothedNoise1(integer_X + 1, integer_Y);
  91. double v3 = SmoothedNoise1(integer_X, integer_Y + 1);
  92. double v4 = SmoothedNoise1(integer_X + 1, integer_Y + 1);
  93. double i1 = Interpolate(v1, v2, fractional_X);
  94. double i2 = Interpolate(v3, v4, fractional_X);
  95. return Interpolate(i1, i2, fractional_Y);
  96. }
  97. public static double PerlinNoise2D(double x, double y, int octaves, double persistence)
  98. {
  99. double total = 0.0;
  100. for (int i = 0; i < octaves; i++)
  101. {
  102. double frequency = Math.Pow(2, i);
  103. double amplitude = Math.Pow(persistence, i);
  104. total += InterpolatedNoise(x * frequency, y * frequency) * amplitude;
  105. }
  106. return total;
  107. }
  108. }
  109. }