260 lines
11 KiB
C++
260 lines
11 KiB
C++
/********************************************************************************
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* ReactPhysics3D physics library, http://code.google.com/p/reactphysics3d/ *
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* Copyright (c) 2010-2013 Daniel Chappuis *
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*********************************************************************************
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* *
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* This software is provided 'as-is', without any express or implied warranty. *
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* In no event will the authors be held liable for any damages arising from the *
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* use of this software. *
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* *
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* Permission is granted to anyone to use this software for any purpose, *
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* including commercial applications, and to alter it and redistribute it *
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* freely, subject to the following restrictions: *
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* *
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* 1. The origin of this software must not be misrepresented; you must not claim *
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* that you wrote the original software. If you use this software in a *
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* product, an acknowledgment in the product documentation would be *
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* appreciated but is not required. *
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* *
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* 2. Altered source versions must be plainly marked as such, and must not be *
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* misrepresented as being the original software. *
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* *
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* 3. This notice may not be removed or altered from any source distribution. *
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* *
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********************************************************************************/
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// Libraries
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#include "CylinderShape.h"
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#include "collision/ProxyShape.h"
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#include "configuration.h"
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using namespace reactphysics3d;
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// Constructor
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CylinderShape::CylinderShape(decimal radius, decimal height, decimal margin)
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: CollisionShape(CYLINDER, margin), mRadius(radius),
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mHalfHeight(height/decimal(2.0)) {
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assert(radius > decimal(0.0));
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assert(height > decimal(0.0));
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}
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// Private copy-constructor
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CylinderShape::CylinderShape(const CylinderShape& shape)
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: CollisionShape(shape), mRadius(shape.mRadius), mHalfHeight(shape.mHalfHeight) {
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}
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// Destructor
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CylinderShape::~CylinderShape() {
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}
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// Return a local support point in a given direction with the object margin
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Vector3 CylinderShape::getLocalSupportPointWithMargin(const Vector3& direction,
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void** cachedCollisionData) const {
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// Compute the support point without the margin
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Vector3 supportPoint = getLocalSupportPointWithoutMargin(direction, NULL);
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// Add the margin to the support point
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Vector3 unitVec(0.0, 1.0, 0.0);
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if (direction.lengthSquare() > MACHINE_EPSILON * MACHINE_EPSILON) {
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unitVec = direction.getUnit();
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}
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supportPoint += unitVec * mMargin;
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return supportPoint;
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}
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// Return a local support point in a given direction without the object margin
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Vector3 CylinderShape::getLocalSupportPointWithoutMargin(const Vector3& direction,
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void** cachedCollisionData) const {
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Vector3 supportPoint(0.0, 0.0, 0.0);
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decimal uDotv = direction.y;
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Vector3 w(direction.x, 0.0, direction.z);
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decimal lengthW = sqrt(direction.x * direction.x + direction.z * direction.z);
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if (lengthW > MACHINE_EPSILON) {
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if (uDotv < 0.0) supportPoint.y = -mHalfHeight;
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else supportPoint.y = mHalfHeight;
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supportPoint += (mRadius / lengthW) * w;
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}
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else {
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if (uDotv < 0.0) supportPoint.y = -mHalfHeight;
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else supportPoint.y = mHalfHeight;
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}
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return supportPoint;
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}
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// Raycast method with feedback information
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/// Algorithm based on the one described at page 194 in Real-ime Collision Detection by
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/// Morgan Kaufmann.
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bool CylinderShape::raycast(const Ray& ray, RaycastInfo& raycastInfo, ProxyShape* proxyShape) const {
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// Transform the ray direction and origin in local-space coordinates
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const Transform localToWorldTransform = proxyShape->getLocalToWorldTransform();
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const Transform worldToLocalTransform = localToWorldTransform.getInverse();
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const Vector3 pointA = worldToLocalTransform * ray.point1;
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const Vector3 pointB = worldToLocalTransform * ray.point2;
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const Vector3 n = pointB - pointA;
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const decimal epsilon = decimal(0.01);
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Vector3 p(decimal(0), -mHalfHeight, decimal(0));
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Vector3 q(decimal(0), mHalfHeight, decimal(0));
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Vector3 d = q - p;
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Vector3 m = pointA - p;
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decimal t;
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decimal mDotD = m.dot(d);
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decimal nDotD = n.dot(d);
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decimal dDotD = d.dot(d);
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// Test if the segment is outside the cylinder
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if (mDotD < decimal(0.0) && mDotD + nDotD < decimal(0.0)) return false;
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if (mDotD > dDotD && mDotD + nDotD > dDotD) return false;
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decimal nDotN = n.dot(n);
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decimal mDotN = m.dot(n);
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decimal a = dDotD * nDotN - nDotD * nDotD;
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decimal k = m.dot(m) - mRadius * mRadius;
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decimal c = dDotD * k - mDotD * mDotD;
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// If the ray is parallel to the cylinder axis
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if (std::abs(a) < epsilon) {
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// If the origin is outside the surface of the cylinder, we return no hit
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if (c > decimal(0.0)) return false;
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// Here we know that the segment intersect an endcap of the cylinder
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// If the ray intersects with the "p" endcap of the cylinder
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if (mDotD < decimal(0.0)) {
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t = -mDotN / nDotN;
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// If the intersection is behind the origin of the ray or beyond the maximum
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// raycasting distance, we return no hit
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if (t < decimal(0.0) || t > ray.maxFraction) return false;
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// Compute the hit information
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Vector3 localHitPoint = pointA + t * n;
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raycastInfo.body = proxyShape->getBody();
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raycastInfo.proxyShape = proxyShape;
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raycastInfo.hitFraction = t;
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raycastInfo.worldPoint = localToWorldTransform * localHitPoint;
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Vector3 normalDirection(0, decimal(-1), 0);
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raycastInfo.worldNormal = localToWorldTransform.getOrientation() * normalDirection;
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return true;
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}
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else if (mDotD > dDotD) { // If the ray intersects with the "q" endcap of the cylinder
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t = (nDotD - mDotN) / nDotN;
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// If the intersection is behind the origin of the ray or beyond the maximum
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// raycasting distance, we return no hit
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if (t < decimal(0.0) || t > ray.maxFraction) return false;
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// Compute the hit information
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Vector3 localHitPoint = pointA + t * n;
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raycastInfo.body = proxyShape->getBody();
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raycastInfo.proxyShape = proxyShape;
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raycastInfo.hitFraction = t;
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raycastInfo.worldPoint = localToWorldTransform * localHitPoint;
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Vector3 normalDirection(0, decimal(1.0), 0);
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raycastInfo.worldNormal = localToWorldTransform.getOrientation() * normalDirection;
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return true;
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}
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else { // If the origin is inside the cylinder, we return no hit
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return false;
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}
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}
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decimal b = dDotD * mDotN - nDotD * mDotD;
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decimal discriminant = b * b - a * c;
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// If the discriminant is negative, no real roots and therfore, no hit
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if (discriminant < decimal(0.0)) return false;
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// Compute the smallest root (first intersection along the ray)
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decimal t0 = t = (-b - std::sqrt(discriminant)) / a;
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// If the intersection is outside the cylinder on "p" endcap side
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decimal value = mDotD + t * nDotD;
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if (value < decimal(0.0)) {
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// If the ray is pointing away from the "p" endcap, we return no hit
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if (nDotD <= decimal(0.0)) return false;
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// Compute the intersection against the "p" endcap (intersection agains whole plane)
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t = -mDotD / nDotD;
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// Keep the intersection if the it is inside the cylinder radius
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if (k + t * (decimal(2.0) * mDotN + t) > decimal(0.0)) return false;
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// If the intersection is behind the origin of the ray or beyond the maximum
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// raycasting distance, we return no hit
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if (t < decimal(0.0) || t > ray.maxFraction) return false;
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// Compute the hit information
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Vector3 localHitPoint = pointA + t * n;
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raycastInfo.body = proxyShape->getBody();
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raycastInfo.proxyShape = proxyShape;
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raycastInfo.hitFraction = t;
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raycastInfo.worldPoint = localToWorldTransform * localHitPoint;
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Vector3 normalDirection(0, decimal(-1.0), 0);
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raycastInfo.worldNormal = localToWorldTransform.getOrientation() * normalDirection;
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return true;
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}
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else if (value > dDotD) { // If the intersection is outside the cylinder on the "q" side
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// If the ray is pointing away from the "q" endcap, we return no hit
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if (nDotD >= decimal(0.0)) return false;
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// Compute the intersection against the "q" endcap (intersection against whole plane)
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t = (dDotD - mDotD) / nDotD;
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// Keep the intersection if it is inside the cylinder radius
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if (k + dDotD - decimal(2.0) * mDotD + t * (decimal(2.0) * (mDotN - nDotD) + t) >
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decimal(0.0)) return false;
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// If the intersection is behind the origin of the ray or beyond the maximum
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// raycasting distance, we return no hit
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if (t < decimal(0.0) || t > ray.maxFraction) return false;
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// Compute the hit information
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Vector3 localHitPoint = pointA + t * n;
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raycastInfo.body = proxyShape->getBody();
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raycastInfo.proxyShape = proxyShape;
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raycastInfo.hitFraction = t;
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raycastInfo.worldPoint = localToWorldTransform * localHitPoint;
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Vector3 normalDirection(0, decimal(1.0), 0);
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raycastInfo.worldNormal = localToWorldTransform.getOrientation() * normalDirection;
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return true;
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}
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t = t0;
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// If the intersection is behind the origin of the ray or beyond the maximum
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// raycasting distance, we return no hit
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if (t < decimal(0.0) || t > ray.maxFraction) return false;
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// Compute the hit information
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Vector3 localHitPoint = pointA + t * n;
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raycastInfo.body = proxyShape->getBody();
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raycastInfo.proxyShape = proxyShape;
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raycastInfo.hitFraction = t;
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raycastInfo.worldPoint = localToWorldTransform * localHitPoint;
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Vector3 v = localHitPoint - p;
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Vector3 w = (v.dot(d) / d.lengthSquare()) * d;
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Vector3 normalDirection = (localHitPoint - (p + w)).getUnit();
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raycastInfo.worldNormal = localToWorldTransform.getOrientation() * normalDirection;
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return true;
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}
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