Geometry.ComputeBoundingSphere Method

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How Do I...?

Computes a bounding sphere for a mesh.

Definition

Visual Basic Public Shared Function ComputeBoundingSphere( _
    ByVal pointsFvf As Array, _
    ByVal strideSize As Integer, _
    ByRef center As Vector3 _
) As Single
C# public static float ComputeBoundingSphere(
    Array pointsFvf,
    int strideSize,
    out Vector3 center
);
C++ public:
static float ComputeBoundingSphere(
    Array^ pointsFvf,
    int strideSize,
    [Out] Vector3% center
);
JScript public static function ComputeBoundingSphere(
    pointsFvf : Array,
    strideSize : int,
    center : Vector3
) : float;

Parameters

pointsFvf System.Array
Array that contains the points around which the bounding box is constructed.
strideSize System.Int32
center Microsoft.DirectX.Vector3
A Vector3 structure that defines the coordinate center of the returned bounding sphere.

Return Value

System.Single
Radius of the returned bounding sphere.

How Do I...?

Compute a Bounding Sphere from a Mesh

This example shows how to generate a simple bounding sphere around a 3-D object, using the Geometry.ComputeBoundingSphere method. A bounding sphere has many possible uses in 3-D graphics; for example, to help test whether one 3-D object intersects with another.

In the following C# code example, a vertex buffer is created from the vertex data of the mesh object. The new vertex buffer is then locked so that Geometry algorithms can be computed on it. The output of the ComputeBoundingSphere is the radius from the center to the farthest extremity of the mesh object. The mesh object is assumed to be a valid mesh loaded with Mesh.FromFile.

              [C#]
              

float objectRadius = 0.0f;
Vector3 objectCenter = new Vector3();

using (VertexBuffer vb = Mesh.VertexBuffer)
{
    GraphicsStream vertexData = vb.Lock(0, 0, LockFlags.None);
    objectRadius = Geometry.ComputeBoundingSphere(vertexData,
                                                  mesh.NumberVertices,
                                                  mesh.VertexFormat,
                                                  out objectCenter);
    vb.Unlock();
}

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