Skip to content

Ray3d.md

Latest commit

 

History

History
86 lines (65 loc) · 2.86 KB

Ray3d.md

File metadata and controls

86 lines (65 loc) · 2.86 KB

Ray3d Class

Overview

The Ray3d class represents a half-bounded line in 3D space, defined by a base point and a direction vector. Unlike Line3d (unbounded in both directions), a ray extends infinitely in only one direction from its base point.

Namespace

Autodesk.AutoCAD.Geometry

Key Properties

Property Type Description
BasePoint Point3d Gets the starting point of the ray
Direction Vector3d Gets the direction vector of the ray

Key Methods

Method Return Type Description
GetClosestPointTo(Point3d) Point3d Gets closest point on ray to given point
DistanceTo(Point3d) double Gets distance from point to ray
IsOn(Point3d) bool Checks if point is on ray
IntersectWith(...) Point3d Gets intersection with another geometric object

Code Examples

Example 1: Creating Rays

// Ray from origin pointing along positive X axis
Point3d basePoint = Point3d.Origin;
Vector3d direction = Vector3d.XAxis;

Ray3d ray = new Ray3d(basePoint, direction);

ed.WriteMessage($"\nRay created");
ed.WriteMessage($"\nBase point: {ray.BasePoint}");
ed.WriteMessage($"\nDirection: {ray.Direction}");

Example 2: Ray Casting

// Cast ray from camera position toward target
Point3d cameraPos = new Point3d(0, 0, 10);
Point3d target = new Point3d(5, 5, 0);

Vector3d direction = cameraPos.GetVectorTo(target).GetNormal();
Ray3d ray = new Ray3d(cameraPos, direction);

// Check if ray hits a point
Point3d testPoint = new Point3d(2.5, 2.5, 5);
double distance = ray.DistanceTo(testPoint);

ed.WriteMessage($"\nRay from camera to target");
ed.WriteMessage($"\nDistance to test point: {distance:F4}");

Example 3: Finding Closest Point on Ray

Ray3d ray = new Ray3d(Point3d.Origin, Vector3d.XAxis);
Point3d testPoint = new Point3d(10, 5, 0);

Point3d closestPoint = ray.GetClosestPointTo(testPoint);
double distance = ray.DistanceTo(testPoint);

ed.WriteMessage($"\nTest point: {testPoint}");
ed.WriteMessage($"\nClosest point on ray: {closestPoint}");
ed.WriteMessage($"\nDistance: {distance:F4}");

Best Practices

  1. Direction: Should be normalized (unit vector)
  2. Half-Bounded: Extends infinitely from base point in direction only
  3. Ray Casting: Commonly used for collision detection and picking
  4. Closest Point: May be the base point if test point is "behind" the ray

Related Classes

  • Ray2d - 2D half-bounded line
  • Line3d - Unbounded 3D line
  • LineSegment3d - Bounded 3D line segment
  • Point3d - Base point
  • Vector3d - Direction vector

References