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72 lines
2.6 KiB
C#
72 lines
2.6 KiB
C#
// Copyright 2014-2017 ClassicalSharp | Licensed under BSD-3
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using System;
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using ClassicalSharp.Entities;
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using OpenTK;
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namespace ClassicalSharp.Physics {
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/// <summary> Contains various methods for intersecting geometry. </summary>
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public static class Intersection {
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/// <summary> Calculates the intersection points of a ray and a rotated bounding box. </summary>
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public static bool RayIntersectsRotatedBox(Vector3 origin, Vector3 dir, Entity target, out float tMin, out float tMax) {
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// This is the rotated AABB of the model we want to test for intersection
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// *
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// / \ we then perform a counter *---* and we can then do
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// ====>* x * rotation to the rotated AABB | x | a standard AABB test
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// \ / and ray origin and direction *---* with the rotated ray
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// * /
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// /
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Vector3 rotatedOrigin = target.Position + Utils.RotateY(origin - target.Position, -target.HeadYRadians);
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Vector3 rotatedDir = Utils.RotateY(dir, -target.HeadYRadians);
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AABB bb = target.PickingBounds;
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return RayIntersectsBox(rotatedOrigin, rotatedDir, bb.Min, bb.Max, out tMin, out tMax);
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}
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//http://www.cs.utah.edu/~awilliam/box/box.pdf
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/// <summary> Calculates the intersection points of a ray and a bounding box. </summary>
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public static bool RayIntersectsBox(Vector3 origin, Vector3 dir, Vector3 min, Vector3 max,
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out float t0, out float t1) {
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t0 = t1 = 0;
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float tmin, tmax, tymin, tymax, tzmin, tzmax;
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float invDirX = 1 / dir.X;
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if (invDirX >= 0) {
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tmin = (min.X - origin.X) * invDirX;
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tmax = (max.X - origin.X) * invDirX;
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} else {
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tmin = (max.X - origin.X) * invDirX;
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tmax = (min.X - origin.X) * invDirX;
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}
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float invDirY = 1 / dir.Y;
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if (invDirY >= 0) {
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tymin = (min.Y - origin.Y) * invDirY;
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tymax = (max.Y - origin.Y) * invDirY;
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} else {
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tymin = (max.Y - origin.Y) * invDirY;
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tymax = (min.Y - origin.Y) * invDirY;
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}
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if (tmin > tymax || tymin > tmax) return false;
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if (tymin > tmin) tmin = tymin;
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if (tymax < tmax) tmax = tymax;
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float invDirZ = 1 / dir.Z;
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if (invDirZ >= 0) {
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tzmin = (min.Z - origin.Z) * invDirZ;
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tzmax = (max.Z - origin.Z) * invDirZ;
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} else {
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tzmin = (max.Z - origin.Z) * invDirZ;
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tzmax = (min.Z - origin.Z) * invDirZ;
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}
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if (tmin > tzmax || tzmin > tmax) return false;
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if (tzmin > tmin) tmin = tzmin;
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if (tzmax < tmax) tmax = tzmax;
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t0 = tmin;
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t1 = tmax;
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return t0 >= 0;
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}
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}
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}
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