Geometry Class (Microsoft.DirectX.Direct3D)

How Do I...?

• Compute a Bounding Sphere from a Mesh

Contains miscellaneous math-related functions.

Definition

Visual Basic	NotInheritable MustInherit Public Class Geometry     Inherits Object
C#	public abstract sealed class Geometry : Object
C++	public ref class Geometry abstract sealed : Object
JScript	public final abstract class Geometry extends Object

Members Table

The following table lists the members exposed by the object.

Methods

Method	Description
BoxBoundProbe	Determines whether a ray intersects the volume of a bounding box.
ComputeBoundingBox	Computes a coordinate axis-oriented bounding box.
ComputeBoundingSphere	Computes a bounding sphere for a mesh.
ComputeTangentFrame	Performs tangent frame computations on a mesh. Tangent, binormal, and optionally normal vectors are generated. Singularities are handled as required by grouping edges and splitting vertices.
DegreeToRadian	Converts degrees to radians.
FresnelTerm	Calculates the Fresnel term.
IntersectTri	Computes the intersection of a ray and a triangle.
OptimizeFaces	Optimizes a set of faces.
OptimizeVertices	Optimizes a set of vertices.
RadianToDegree	Converts radians to degrees.
SphereBoundProbe	Determines whether a ray intersects the volume of a sphere's bounding box.

Inheritance Hierarchy

Object

Geometry

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();
}

Class Information

Namespace	Microsoft.DirectX.Direct3D
Assembly	Microsoft.DirectX.Direct3DX (microsoft.directx.direct3dx.dll)
Strong Name	Microsoft.DirectX.Direct3DX,  Version=1.0.900.0,  Culture=neutral,  PublicKeyToken=d3231b57b74a1492