Method FramesFromWorldAnchor

Namespace

Box3D

Assembly

Box3D.NET.dll

FramesFromWorldAnchor(Body, Body, Vector3, Vector3)

Builds a matched pair of joint frames from a world-space anchor and axis.

public static (JointFrame FrameA, JointFrame FrameB) FramesFromWorldAnchor(Body bodyA, Body bodyB, Vector3 worldAnchor, Vector3 worldAxis)

Parameters

bodyA Body

The first body.

bodyB Body

The second body.

worldAnchor Vector3

The point both bodies are pinned to, in world space.

worldAxis Vector3

The axis the joint acts about, in world space. It is placed on the frames' z axis, which is what revolute, spherical and parallel joints turn about. Prismatic and wheel joints use the frames' x axis, so pass the sliding direction as the axis and the joint will slide along it.

Returns

(JointFrame FrameA, JointFrame FrameB)

The frames, expressed in each body's local space.

Examples

// A door hinged on its left edge, turning about the world up axis.
var (frameA, frameB) = Joint.FramesFromWorldAnchor(
    frame, door, hingePoint, Vector3.UnitY);

world.CreateRevoluteJoint(new RevoluteJointDefinition
{
    Base = JointDefinition.Connect(frame, door, frameA, frameB),
});

Remarks

This is the calculation people otherwise get wrong: the two frames must describe the same world pose from each body's point of view, or the joint starts out already violated and snaps on the first step.