我正在使用XNA提供的基元绘制圆柱体，我想要做的是，当鼠标悬停在圆柱体上时，我会检测到它。我尝试使用边界球但它不起作用，因为它不准确。我不知道该怎么办。有什么帮助吗？
我想做的总结。 1-为此气缸创建边界框 2-旋转此边界框。
可以在此处找到“绘制圆柱的代码”
http://xbox.create.msdn.com/en-US/education/catalog/sample/primitives_3d
#region File Description
//-----------------------------------------------------------------------------
// CylinderPrimitive.cs
//
// Microsoft XNA Community Game Platform
// Copyright (C) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
#endregion
#region Using Statements
using System;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
#endregion
namespace TheProteinBundle
{
/// <summary>
/// Geometric primitive class for drawing cylinders.
/// </summary>
public class CylinderPrimitive : GeometricPrimitive
{
/// <summary>
/// Constructs a new cylinder primitive, using default settings.
/// </summary>
public CylinderPrimitive(GraphicsDevice graphicsDevice)
: this(graphicsDevice, 1, 1, 32)
{
}
/// <summary>
/// Constructs a new cylinder primitive,
/// with the specified size and tessellation level.
/// </summary>
public CylinderPrimitive(GraphicsDevice graphicsDevice,
float height, float diameter, int tessellation)
{
if (tessellation < 3)
throw new ArgumentOutOfRangeException("tessellation");
height /= 2;
float radius = diameter / 2;
// Create a ring of triangles around the outside of the cylinder.
for (int i = 0; i < tessellation; i++)
{
Vector3 normal = GetCircleVector(i, tessellation);
AddVertex(normal * radius + Vector3.Up * height, normal);
AddVertex(normal * radius + Vector3.Down * height, normal);
AddIndex(i * 2);
AddIndex(i * 2 + 1);
AddIndex((i * 2 + 2) % (tessellation * 2));
AddIndex(i * 2 + 1);
AddIndex((i * 2 + 3) % (tessellation * 2));
AddIndex((i * 2 + 2) % (tessellation * 2));
}
// Create flat triangle fan caps to seal the top and bottom.
CreateCap(tessellation, height, radius, Vector3.Up);
CreateCap(tessellation, height, radius, Vector3.Down);
InitializePrimitive(graphicsDevice);
base.boundingSphere.Center = Vector3.Zero;
if (height > diameter)
base.boundingSphere.Radius = height;
else
base.boundingSphere.Radius = diameter;
}
/// <summary>
/// Helper method creates a triangle fan to close the ends of the cylinder.
/// </summary>
void CreateCap(int tessellation, float height, float radius, Vector3 normal)
{
// Create cap indices.
for (int i = 0; i < tessellation - 2; i++)
{
if (normal.Y > 0)
{
AddIndex(CurrentVertex);
AddIndex(CurrentVertex + (i + 1) % tessellation);
AddIndex(CurrentVertex + (i + 2) % tessellation);
}
else
{
AddIndex(CurrentVertex);
AddIndex(CurrentVertex + (i + 2) % tessellation);
AddIndex(CurrentVertex + (i + 1) % tessellation);
}
}
// Create cap vertices.
for (int i = 0; i < tessellation; i++)
{
Vector3 position = GetCircleVector(i, tessellation) * radius +
normal * height;
AddVertex(position, normal);
}
}
/// <summary>
/// Helper method computes a point on a circle.
/// </summary>
static Vector3 GetCircleVector(int i, int tessellation)
{
float angle = i * MathHelper.TwoPi / tessellation;
float dx = (float)Math.Cos(angle);
float dz = (float)Math.Sin(angle);
return new Vector3(dx, 0, dz);
}
}
}
使用此课程
#region File Description
//-----------------------------------------------------------------------------
// GeometricPrimitive.cs
//
// Microsoft XNA Community Game Platform
// Copyright (C) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
#endregion
#region Using Statements
using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
#endregion
namespace TheProteinBundle
{
/// <summary>
/// Base class for simple geometric primitive models. This provides a vertex
/// buffer, an index buffer, plus methods for drawing the model. Classes for
/// specific types of primitive (CubePrimitive, SpherePrimitive, etc.) are
/// derived from this common base, and use the AddVertex and AddIndex methods
/// to specify their geometry.
/// </summary>
public abstract class GeometricPrimitive : IDisposable
{
#region Fields
// During the process of constructing a primitive model, vertex
// and index data is stored on the CPU in these managed lists.
List<VertexPositionNormal> vertices = new List<VertexPositionNormal>();
List<ushort> indices = new List<ushort>();
// Once all the geometry has been specified, the InitializePrimitive
// method copies the vertex and index data into these buffers, which
// store it on the GPU ready for efficient rendering.
VertexBuffer vertexBuffer;
IndexBuffer indexBuffer;
BasicEffect basicEffect;
public BoundingSphere boundingsphere2;
public BoundingSphere boundingSphere;
public Matrix world;
#endregion
#region Initialization
/// <summary>
/// Adds a new vertex to the primitive model. This should only be called
/// during the initialization process, before InitializePrimitive.
/// </summary>
protected void AddVertex(Vector3 position, Vector3 normal)
{
vertices.Add(new VertexPositionNormal(position, normal));
}
/// <summary>
/// Adds a new index to the primitive model. This should only be called
/// during the initialization process, before InitializePrimitive.
/// </summary>
protected void AddIndex(int index)
{
if (index > ushort.MaxValue)
throw new ArgumentOutOfRangeException("index");
indices.Add((ushort)index);
}
/// <summary>
/// Queries the index of the current vertex. This starts at
/// zero, and increments every time AddVertex is called.
/// </summary>
protected int CurrentVertex
{
get { return vertices.Count; }
}
/// <summary>
/// Once all the geometry has been specified by calling AddVertex and AddIndex,
/// this method copies the vertex and index data into GPU format buffers, ready
/// for efficient rendering.
protected void InitializePrimitive(GraphicsDevice graphicsDevice)
{
// Create a vertex declaration, describing the format of our vertex data.
// Create a vertex buffer, and copy our vertex data into it.
vertexBuffer = new VertexBuffer(graphicsDevice,
typeof(VertexPositionNormal),
vertices.Count, BufferUsage.None);
vertexBuffer.SetData(vertices.ToArray());
// Create an index buffer, and copy our index data into it.
indexBuffer = new IndexBuffer(graphicsDevice, typeof(ushort),
indices.Count, BufferUsage.None);
indexBuffer.SetData(indices.ToArray());
// Create a BasicEffect, which will be used to render the primitive.
basicEffect = new BasicEffect(graphicsDevice);
basicEffect.EnableDefaultLighting();
}
/// <summary>
/// Finalizer.
/// </summary>
~GeometricPrimitive()
{
Dispose(false);
}
/// <summary>
/// Frees resources used by this object.
/// </summary>
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
/// <summary>
/// Frees resources used by this object.
/// </summary>
protected virtual void Dispose(bool disposing)
{
if (disposing)
{
if (vertexBuffer != null)
vertexBuffer.Dispose();
if (indexBuffer != null)
indexBuffer.Dispose();
if (basicEffect != null)
basicEffect.Dispose();
}
}
#endregion
public void TransformBoundingSphere(Matrix TransformToWorld)
{
boundingSphere.Transform(ref TransformToWorld, out boundingsphere2);
}
public bool CheckRayIntersection(Ray ray)
{
if (ray.Intersects(boundingsphere2).HasValue) return true;
return false;
}
#region Draw
/// <summary>
/// Draws the primitive model, using the specified effect. Unlike the other
/// Draw overload where you just specify the world/view/projection matrices
/// and color, this method does not set any renderstates, so you must make
/// sure all states are set to sensible values before you call it.
/// </summary>
public void Draw(Effect effect)
{
GraphicsDevice graphicsDevice = effect.GraphicsDevice;
// Set our vertex declaration, vertex buffer, and index buffer.
graphicsDevice.SetVertexBuffer(vertexBuffer);
graphicsDevice.Indices = indexBuffer;
foreach (EffectPass effectPass in effect.CurrentTechnique.Passes)
{
effectPass.Apply();
int primitiveCount = indices.Count / 3;
graphicsDevice.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0,
vertices.Count, 0, primitiveCount);
}
}
/// <summary>
/// Draws the primitive model, using a BasicEffect shader with default
/// lighting. Unlike the other Draw overload where you specify a custom
/// effect, this method sets important renderstates to sensible values
/// for 3D model rendering, so you do not need to set these states before
/// you call it.
/// </summary>
public void Draw(Matrix world, Matrix view, Matrix projection, Color color)
{
// Set BasicEffect parameters.
basicEffect.World = world;
basicEffect.View = view;
basicEffect.Projection = projection;
basicEffect.DiffuseColor = color.ToVector3();
basicEffect.Alpha = color.A / 255.0f;
GraphicsDevice device = basicEffect.GraphicsDevice;
device.DepthStencilState = DepthStencilState.Default;
if (color.A < 255)
{
// Set renderstates for alpha blended rendering.
device.BlendState = BlendState.AlphaBlend;
}
else
{
// Set renderstates for opaque rendering.
device.BlendState = BlendState.Opaque;
}
// Draw the model, using BasicEffect.
Draw(basicEffect);
}
#endregion
}
}