1 | using System;
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2 |
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3 | namespace Netron.Diagramming.Core.Layout.Force {
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4 | /// <summary>
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5 | /// Implements a viscosity/drag force to help stabilize items.
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6 | /// </summary>
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7 | public class DragForce : AbstractForce {
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8 | #region Fields
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9 | /// <summary>
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10 | /// the parameter names
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11 | /// </summary>
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12 | private static String[] pnames = new String[] { "DragCoefficient" };
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13 | /// <summary>
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14 | /// dragging coefficient
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15 | /// </summary>
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16 | public static float DefaultDragCoeff = 0.01f;
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17 | /// <summary>
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18 | /// minimum dragging coefficient
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19 | /// </summary>
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20 | public static float DefaultMinDragCoeff = 0.0f;
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21 | /// <summary>
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22 | /// maximum drag coefficient
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23 | /// </summary>
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24 | public static float DefaultMaxDragCoeff = 0.1f;
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25 | /// <summary>
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26 | /// current dragging coefficient
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27 | /// </summary>
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28 | public static int DragCoeff = 0;
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29 | #endregion
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30 |
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31 | #region Properties
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32 | /// <summary>
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33 | /// Returns true.
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34 | /// </summary>
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35 | /// <value></value>
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36 | public override bool IsItemForce {
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37 | get {
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38 | return true;
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39 | }
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40 | }
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41 | /// <summary>
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42 | /// Gets the parameter names.
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43 | /// </summary>
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44 | /// <value></value>
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45 | /// <returns></returns>
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46 | protected override String[] ParameterNames {
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47 | get {
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48 | return pnames;
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49 | }
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50 | }
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51 | #endregion
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52 |
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53 | #region Methods
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54 | /// <summary>
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55 | /// Create a new DragForce.
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56 | /// </summary>
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57 | /// <param name="dragCoeff">The drag coefficient.</param>
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58 | public DragForce(float dragCoeff) {
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59 | parms = new float[] { dragCoeff };
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60 | minValues = new float[] { DefaultMinDragCoeff };
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61 | maxValues = new float[] { DefaultMaxDragCoeff };
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62 | }
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63 |
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64 | /// <summary>
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65 | /// Create a new DragForce with default drag co-efficient.
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66 | /// </summary>
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67 | public DragForce()
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68 | : this(DefaultDragCoeff) {
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69 |
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70 | }
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71 |
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72 | /// <summary>
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73 | /// Returns the force acting on the given item.
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74 | /// </summary>
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75 | /// <param name="item"></param>
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76 | public override void GetForce(ForceItem item) {
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77 | item.Force[0] -= parms[DragCoeff] * item.Velocity[0];
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78 | item.Force[1] -= parms[DragCoeff] * item.Velocity[1];
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79 | }
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80 | #endregion
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81 |
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82 |
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83 | }
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84 | }
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