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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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 | #region License/* FNA - XNA4 Reimplementation for Desktop Platforms * Copyright 2009-2016 Ethan Lee and the MonoGame Team * * Released under the Microsoft Public License. * See LICENSE for details. *//* Derived from code by the Mono.Xna Team (Copyright 2006). * Released under the MIT License. See monoxna.LICENSE for details. */#endregion#region Using Statementsusing System;using System.ComponentModel;using System.Diagnostics;using Microsoft.Xna.Framework.Design;#endregionnamespace Microsoft.Xna.Framework{ [Serializable] [TypeConverter(typeof(RayConverter))] [DebuggerDisplay("{DebugDisplayString,nq}")] public struct Ray : IEquatable<Ray> { #region Internal Properties internal string DebugDisplayString { get { return string.Concat( "Pos( ", Position.DebugDisplayString, " ) \r\n", "Dir( ", Direction.DebugDisplayString, " )" ); } } #endregion #region Public Fields public Vector3 Position; public Vector3 Direction; #endregion #region Public Constructors public Ray(Vector3 position, Vector3 direction) { Position = position; Direction = direction; } #endregion #region Public Methods public override bool Equals(object obj) { return (obj is Ray) && Equals((Ray) obj); } public bool Equals(Ray other) { return ( this.Position.Equals(other.Position) && this.Direction.Equals(other.Direction) ); } public override int GetHashCode() { return Position.GetHashCode() ^ Direction.GetHashCode(); } // Adapted from http://www.scratchapixel.com/lessons/3d-basic-lessons/lesson-7-intersecting-simple-shapes/ray-box-intersection/ public float? Intersects(BoundingBox box) { float? tMin = null, tMax = null; if (MathHelper.WithinEpsilon(Direction.X, 0.0f)) { if (Position.X < box.Min.X || Position.X > box.Max.X) { return null; } } else { tMin = (box.Min.X - Position.X) / Direction.X; tMax = (box.Max.X - Position.X) / Direction.X; if (tMin > tMax) { float? temp = tMin; tMin = tMax; tMax = temp; } } if (MathHelper.WithinEpsilon(Direction.Y, 0.0f)) { if (Position.Y < box.Min.Y || Position.Y > box.Max.Y) { return null; } } else { float tMinY = (box.Min.Y - Position.Y) / Direction.Y; float tMaxY = (box.Max.Y - Position.Y) / Direction.Y; if (tMinY > tMaxY) { float temp = tMinY; tMinY = tMaxY; tMaxY = temp; } if ( (tMin.HasValue && tMin > tMaxY) || (tMax.HasValue && tMinY > tMax) ) { return null; } if (!tMin.HasValue || tMinY > tMin) tMin = tMinY; if (!tMax.HasValue || tMaxY < tMax) tMax = tMaxY; } if (MathHelper.WithinEpsilon(Direction.Z, 0.0f)) { if (Position.Z < box.Min.Z || Position.Z > box.Max.Z) { return null; } } else { float tMinZ = (box.Min.Z - Position.Z) / Direction.Z; float tMaxZ = (box.Max.Z - Position.Z) / Direction.Z; if (tMinZ > tMaxZ) { float temp = tMinZ; tMinZ = tMaxZ; tMaxZ = temp; } if ( (tMin.HasValue && tMin > tMaxZ) || (tMax.HasValue && tMinZ > tMax) ) { return null; } if (!tMin.HasValue || tMinZ > tMin) tMin = tMinZ; if (!tMax.HasValue || tMaxZ < tMax) tMax = tMaxZ; } /* Having a positive tMin and a negative tMax means the ray is inside the * box we expect the intesection distance to be 0 in that case. */ if ((tMin.HasValue && tMin < 0) && tMax > 0) return 0; /* A negative tMin means that the intersection point is behind the ray's * origin. We discard these as not hitting the AABB. */ if (tMin < 0) return null; return tMin; } public void Intersects(ref BoundingBox box, out float? result) { result = Intersects(box); } public float? Intersects(BoundingSphere sphere) { float? result; Intersects(ref sphere, out result); return result; } public float? Intersects(Plane plane) { float? result; Intersects(ref plane, out result); return result; } public float? Intersects(BoundingFrustum frustum) { float? result; frustum.Intersects(ref this, out result); return result; } public void Intersects(ref Plane plane, out float? result) { float den = Vector3.Dot(Direction, plane.Normal); if (Math.Abs(den) < 0.00001f) { result = null; return; } result = (-plane.D - Vector3.Dot(plane.Normal, Position)) / den; if (result < 0.0f) { if (result < -0.00001f) { result = null; return; } result = 0.0f; } } public void Intersects(ref BoundingSphere sphere, out float? result) { // Find the vector between where the ray starts the the sphere's center. Vector3 difference = sphere.Center - this.Position; float differenceLengthSquared = difference.LengthSquared(); float sphereRadiusSquared = sphere.Radius * sphere.Radius; float distanceAlongRay; /* If the distance between the ray start and the sphere's center is less than * the radius of the sphere, it means we've intersected. Checking the * LengthSquared is faster. */ if (differenceLengthSquared < sphereRadiusSquared) { result = 0.0f; return; } Vector3.Dot(ref this.Direction, ref difference, out distanceAlongRay); // If the ray is pointing away from the sphere then we don't ever intersect. if (distanceAlongRay < 0) { result = null; return; } /* Next we kinda use Pythagoras to check if we are within the bounds of the * sphere. * if x = radius of sphere * if y = distance between ray position and sphere centre * if z = the distance we've travelled along the ray * if x^2 + z^2 - y^2 < 0, we do not intersect */ float dist = ( sphereRadiusSquared + (distanceAlongRay * distanceAlongRay) - differenceLengthSquared ); result = (dist < 0) ? null : distanceAlongRay - (float?) Math.Sqrt(dist); } #endregion #region Public Static Methods public static bool operator !=(Ray a, Ray b) { return !a.Equals(b); } public static bool operator ==(Ray a, Ray b) { return a.Equals(b); } public override string ToString() { return ( "{{Position:" + Position.ToString() + " Direction:" + Direction.ToString() + "}}" ); } #endregion }} |
