Camera.cs - WindowsPhoneDemoGame

using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Input.Touch;
using Microsoft.Xna.Framework.Media;

namespace WindowsPhoneGameDemoObjects
{
    public class Camera : DrawableGameComponent
    {
        private float movementSpeed = 250f;
        private float turnSpeed = 0.4f;

        public bool DenyVerticalMovement = false;

        private const float maxPitch = MathHelper.PiOver2 - 0.3f;

        public Matrix Projection { get; protected set; }
        public Matrix View { get; protected set; }
        public float NearPlane { get { return nearPlane; } set { nearPlane = value; CreateProjection(); } }
        public float FarPlane { get { return farPlane; } set { farPlane = value; CreateProjection(); } }

        protected float nearPlane = 1;
        protected float farPlane = 10000;

        public BoundingFrustum Frustrum { get; protected set; }

        public Vector3 Position;
        public Vector3 Angle;

        public Camera(Game game)
            : base(game)
        {
            CreateProjection();
        }



        public override void Initialize()
        {
            base.Initialize();
        }

        private void CreateProjection()
        {
            Projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.Pi / 4, 1.66f, nearPlane, farPlane);
        }

        protected override void LoadContent()
        {
            base.LoadContent();
        }

        GameTime touchStartTime;
        private void UpdateTouch(GameTime gameTime)
        {
            TouchCollection tc = TouchPanel.GetState();
            if (tc.Count > 0)
            {
                TouchLocation current = tc[0];
                TouchLocation prev;
                if (current.TryGetPreviousLocation(out prev))
                {
                    Angle.X -= MathHelper.ToRadians((current.Position.X - prev.Position.X) * turnSpeed); // pitch
                    Angle.Y += MathHelper.ToRadians((current.Position.Y - prev.Position.Y) * turnSpeed); // yaw

                    while (Angle.Y > MathHelper.Pi * 2)
                        Angle.Y -= MathHelper.Pi * 2;
                    while (Angle.Y < -MathHelper.Pi * 2)
                        Angle.Y += MathHelper.Pi * 2;

                    if (Angle.X > maxPitch)
                        Angle.X = maxPitch;

                    if (Angle.X < -maxPitch)
                        Angle.X = -maxPitch;

                    float time = (float)gameTime.ElapsedGameTime.TotalSeconds;
                    Vector3 forward = -Vector3.Normalize(new Vector3((float)Math.Sin(-Angle.Y),
                        (float)Math.Sin(Angle.X),
                        (float)Math.Cos(-Angle.Y)));
                    if (DenyVerticalMovement)
                    {
                        forward = new Vector3(forward.X, 0, forward.Z);
                        forward.Normalize();
                    }
                    Position += forward * movementSpeed * time;
                }
                else
                    touchStartTime = gameTime;
            }
        }

        public override void Update(GameTime gameTime)
        {

            UpdateTouch(gameTime);
            RecalcView();

            base.Update(gameTime);
        }

        protected void RecalcView()
        {
            View = Matrix.Identity;
            View *= Matrix.CreateTranslation(-Position);
            View *= Matrix.CreateRotationZ(Angle.Z);
            View *= Matrix.CreateRotationY(Angle.Y);
            View *= Matrix.CreateRotationX(Angle.X);

            Frustrum = new BoundingFrustum(Matrix.Multiply(View, Projection));
        }
    }
}