/* * 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; using System.Collections.Generic; using System.Text; namespace libTerrain { partial class Channel { // Ideas for Aerobic erosion // // Unlike thermal (gravity) and hydraulic (water suspension) // aerobic erosion should displace mass by moving sediment // in "hops". The length of the hop being dictated by the // presence of sharp cliffs and wind speed. // The ability to pickup sediment is defined by the total // surface area, such that: // 0 0 0 // 0 1 0 // 0 0 0 // Would be the best possible value for sediment to be // picked up (total difference = 8) and flatter land // will erode less quickly. // Suspended particles assist the erosion process by hitting // the surface and chiselling additional particles off faster // than alone. // Particles are deposited when one of two conditions is met // First: // When particles hit a wall - such that the // wind direction points at a difference >= the // deposition mininum talus. // Second: // When wind speed is lowered to below the minimum // required for transit. An idea for this is to // use the navier-stokes algorithms for simulating // pressure across the terrain. /// /// An experimental erosion algorithm developed by Adam. Moves sediment by factoring the surface area of each height point. /// /// 0..1 The speed of the wind /// The minimum angle at which rock is eroded 0..1 (recommended: <= 0.30) /// The minimum angle at which rock is dropped 0..1 (recommended: >= 0.00) /// The percentage of rock which can be picked up to pickup 0..1 /// The number of erosion rounds (recommended: 25+) /// Drop sediment at the lowest point? public void AerobicErosion(double windspeed, double pickupTalusMinimum, double dropTalusMinimum, double carry, int rounds, bool lowest, bool usingFluidDynamics) { bool debugImages = true; Channel wind = new Channel(w, h) ; Channel sediment = new Channel(w, h); int x, y, i, j; this.Normalise(); wind = this.Copy(); wind.Noise(); if (debugImages) wind.SaveImage("testimg/wind_start.png"); if (usingFluidDynamics) { wind.navierStokes(20, 0.1, 0.0, 0.0); } else { wind.Pertubation(30); } if (debugImages) wind.SaveImage("testimg/wind_begin.png"); for (i = 0; i < rounds; i++) { // Convert some rocks to sand for (x = 1; x < w - 1; x++) { for (y = 1; y < h - 1; y++) { double me = Get(x, y); double surfacearea = 0.3; // Everything will erode even if it's flat. Just slower. for (j = 0; j < 9; j++) { int[] coords = Neighbours(NeighbourSystem.Moore, j); double target = Get(x + coords[0], y + coords[1]); surfacearea += Math.Abs(target - me); } double amount = surfacearea * wind.map[x, y] * carry; if (amount < 0) amount = 0; if (surfacearea > pickupTalusMinimum) { Set(x, y, map[x, y] - amount); sediment.map[x, y] += amount; } } } if (usingFluidDynamics) { sediment.navierStokes(7, 0.1, 0.0, 0.1); Channel noiseChan = new Channel(w, h); noiseChan.Noise(); wind.Blend(noiseChan, 0.01); wind.navierStokes(10, 0.1, 0.01, 0.01); sediment.Distort(wind, windspeed); } else { wind.Pertubation(15); // Can do better later wind.seed++; sediment.Pertubation(10); // Sediment is blown around a bit sediment.seed++; } if (debugImages) wind.SaveImage("testimg/wind_" + i.ToString() + ".png"); // Convert some sand to rock for (x = 1; x < w - 1; x++) { for (y = 1; y < h - 1; y++) { double me = Get(x, y); double surfacearea = 0.01; // Flat land does not get deposition double min = double.MaxValue; int[] minside = new int[2]; for (j = 0; j < 9; j++) { int[] coords = Neighbours(NeighbourSystem.Moore, j); double target = Get(x + coords[0], y + coords[1]); surfacearea += Math.Abs(target - me); if (target < min && lowest) { minside = (int[])coords.Clone(); min = target; } } double amount = surfacearea * (1.0 - wind.map[x, y]) * carry; if (amount < 0) amount = 0; if (surfacearea > dropTalusMinimum) { Set(x + minside[0], y + minside[1], map[x + minside[0], y + minside[1]] + amount); sediment.map[x, y] -= amount; } } } if (debugImages) sediment.SaveImage("testimg/sediment_" + i.ToString() + ".png"); wind.Normalise(); wind *= windspeed; this.Normalise(); } Channel myself = this; myself += sediment; myself.Normalise(); if (debugImages) this.SaveImage("testimg/output.png"); } } }