View Coordinate Transformations
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summary
You are manipulating the parameters of the view coordinate transformation.
Operating environment
Prerequisites
| Supported XNA Versions |
|
| Supported Platforms |
|
| Windows Required Vertex Shader Version | 2.0 |
| Windows Required Pixel Shader Version | 2.0 |
Operating environment
| platform |
|
How to work with the sample
| Works keyboardXbox | 360 controllermouse | touch | ||
|---|---|---|---|---|
| Moving the position of the camera | ↑↓←→ | Left Stick | Left button (auto-move, movement switching) | - |
| Moving the camera's point of interest | W,Z,A,S | Right Stick | Left button (auto-move, movement switching) | - |
| Rotate the camera upward | X,C | trigger | Left button (auto-rotate, switch movements) | - |
substance
About View Transformations
Please refer to the following page for an overview of view coordinate transformations.
field
In this case, we will replace the parameters used for view coordinate conversion with the camera, and operate the three parameters of "camera position", "camera gaze point", and "camera upward direction".
<summary>
カメラの位置
</summary>
private Vector3 cameraPosition = new Vector3(2.0f, 4.0f, 20.0f);
<summary>
カメラの注視点
</summary>
private Vector3 cameraTarget = new Vector3(0.0f, 0.0f, 0.0f);
<summary>
カメラの上方方向回転角度(radian)
</summary>
private float cameraUpVectorRotate = 0.0f;
Working with the Camera
In the Game.Update method, we use the keyboard and controller to manipulate each parameter of the camera. For details of each operation, see "How To" at the top of this page. (The code below is excerpted only from the operation part with the gamepad)
GamePadState gamePadState = GamePad.GetState(PlayerIndex.One);
float speed = 0.25f;
// カメラの位置を移動させる
this.cameraPosition.X += gamePadState.ThumbSticks.Left.X * speed;
this.cameraPosition.Y += gamePadState.ThumbSticks.Left.Y * speed;
// カメラの注視点を移動させる
this.cameraTarget.X += gamePadState.ThumbSticks.Right.X * speed;
this.cameraTarget.Y += gamePadState.ThumbSticks.Right.Y * speed;
// カメラの上方方向を回転させる
this.cameraUpVectorRotate -= gamePadState.Triggers.Left * speed * 0.2f;
this.cameraUpVectorRotate += gamePadState.Triggers.Right * speed * 0.2f;
Creating a View Matrix
The "Matrix.CreateLookAt" method is set with each parameter to create the view matrix.
The first argument specifies the position of the camera, the second argument specifies the camera's point of interest, and the third argument specifies the upward direction of the camera.
Regarding the third argument, "upward direction of the camera", the vector is calculated by rotating around the Z axis based on the Y-axis direction (0,1,0).
// ビューマトリックス作成
Matrix view = Matrix.CreateLookAt(
this.cameraPosition,
this.cameraTarget,
Vector3.Transform(Vector3.Up,
Matrix.CreateRotationZ(this.cameraUpVectorRotate))
);
Matrix.CreateLookAt method
Create a view matrix for the right-handed coordinate system.
| cameraPosition | Vector3 | Camera Position |
| cameraTarget | Vector3 | Camera Point of Interest |
| cameraUpVector | Vector3 | Upward direction of the camera |
| Return Values | Matrix | Get the view matrix |
Vector3.Transform method
Transform the vector into a coordinate transformation.
| position | Vector3 | Source vector |
| matrix | Matrix | Coordinate Transformations |
| Return Values | Vector3 | Vector with coordinate transformations |
Matrix.CreateRotationZ method
Create a rotation matrix around the Z-axis.
| radians | float | Rotation angle (radian) |
| Return Values | Matrix | Rotation matrix about the Z-axis |
A set of view matrices
The box is placed at the point of interest so that the position of the camera's point of interest is easy to understand. In addition, a view matrix is set for each effect.
foreach (ModelMesh mesh in this.box.Meshes)
{
foreach (BasicEffect effect in mesh.Effects)
{
// ライトの設定
effect.EnableDefaultLighting();
// ボックスの位置をカメラの注視点に合わせる
effect.World = Matrix.CreateTranslation(this.cameraTarget);
// ビューマトリックスを設定
effect.View = view;
// プロジェクションマトリックス設定
effect.Projection = projection;
}
mesh.Draw();
}
All Codes
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.Media;
#if WINDOWS_PHONE
using Microsoft.Xna.Framework.Input.Touch;
#endif
namespace ViewMatrix
{
<summary>
ゲームメインクラス
</summary>
public class GameMain : Microsoft.Xna.Framework.Game
{
<summary>
グラフィックデバイス管理クラス
</summary>
private GraphicsDeviceManager graphics = null;
<summary>
スプライトのバッチ化クラス
</summary>
private SpriteBatch spriteBatch = null;
<summary>
スプライトでテキストを描画するためのフォント
</summary>
private SpriteFont font = null;
<summary>
ボックスモデル
</summary>
private Model box = null;
<summary>
XYZモデル
</summary>
private Model xyz = null;
<summary>
カメラの位置
</summary>
private Vector3 cameraPosition = new Vector3(2.0f, 4.0f, 20.0f);
<summary>
カメラの注視点
</summary>
private Vector3 cameraTarget = new Vector3(0.0f, 0.0f, 0.0f);
<summary>
カメラの上方方向回転角度(radian)
</summary>
private float cameraUpVectorRotate = 0.0f;
<summary>
自動動作フラグ
</summary>
private int autoMode = 0;
<summary>
マウスボタン押下フラグ
</summary>
private bool isMousePressed = false;
<summary>
GameMain コンストラクタ
</summary>
public GameMain()
{
// グラフィックデバイス管理クラスの作成
this.graphics = new GraphicsDeviceManager(this);
// ゲームコンテンツのルートディレクトリを設定
this.Content.RootDirectory = "Content";
#if WINDOWS_PHONE
// Windows Phone のデフォルトのフレームレートは 30 FPS
this.TargetElapsedTime = TimeSpan.FromTicks(333333);
// バックバッファサイズの設定
this.graphics.PreferredBackBufferWidth = 480;
this.graphics.PreferredBackBufferHeight = 800;
// フルスクリーン表示
this.graphics.IsFullScreen = true;
#endif
}
<summary>
ゲームが始まる前の初期化処理を行うメソッド
グラフィック以外のデータの読み込み、コンポーネントの初期化を行う
</summary>
protected override void Initialize()
{
// TODO: ここに初期化ロジックを書いてください
// コンポーネントの初期化などを行います
base.Initialize();
}
<summary>
ゲームが始まるときに一回だけ呼ばれ
すべてのゲームコンテンツを読み込みます
</summary>
protected override void LoadContent()
{
// テクスチャーを描画するためのスプライトバッチクラスを作成します
this.spriteBatch = new SpriteBatch(this.GraphicsDevice);
// フォントをコンテンツパイプラインから読み込む
this.font = this.Content.Load<SpriteFont>("Font");
// ボックスモデルを読み込み
this.box = this.Content.Load<Model>("Box");
// XYZ軸モデルを読み込み
this.xyz = this.Content.Load<Model>("XYZ");
}
<summary>
ゲームが終了するときに一回だけ呼ばれ
すべてのゲームコンテンツをアンロードします
</summary>
protected override void UnloadContent()
{
// TODO: ContentManager で管理されていないコンテンツを
// ここでアンロードしてください
}
<summary>
描画以外のデータ更新等の処理を行うメソッド
主に入力処理、衝突判定などの物理計算、オーディオの再生など
</summary>
<param name="gameTime">このメソッドが呼ばれたときのゲーム時間</param>
protected override void Update(GameTime gameTime)
{
KeyboardState keyState = Keyboard.GetState();
MouseState mouseState = Mouse.GetState();
GamePadState gamePadState = GamePad.GetState(PlayerIndex.One);
// Xbox 360 コントローラ、Windows Phone の BACK ボタンを押したときに
// ゲームを終了させます
if (gamePadState.Buttons.Back == ButtonState.Pressed)
{
this.Exit();
}
// マウスによる自動動作切り替え
if (this.isMousePressed == false &&
mouseState.LeftButton == ButtonState.Pressed)
{
this.isMousePressed = true;
this.autoMode = (this.autoMode + 1) % 6;
}
this.isMousePressed = mouseState.LeftButton == ButtonState.Pressed;
float speed = 0.25f;
// カメラの位置を移動させる
this.cameraPosition.X += gamePadState.ThumbSticks.Left.X * speed;
this.cameraPosition.Y += gamePadState.ThumbSticks.Left.Y * speed;
if (keyState.IsKeyDown(Keys.Left))
{
this.cameraPosition.X -= speed;
}
if (keyState.IsKeyDown(Keys.Right))
{
this.cameraPosition.X += speed;
}
if (keyState.IsKeyDown(Keys.Down))
{
this.cameraPosition.Y -= speed;
}
if (keyState.IsKeyDown(Keys.Up))
{
this.cameraPosition.Y += speed;
}
if (this.autoMode == 1)
{
this.cameraPosition.X = (float)Math.Sin(gameTime.TotalGameTime.TotalSeconds) * 10.0f;
}
if (this.autoMode == 2)
{
this.cameraPosition.Y = (float)Math.Sin(gameTime.TotalGameTime.TotalSeconds) * 10.0f;
}
// カメラの注視点を移動させる
this.cameraTarget.X += gamePadState.ThumbSticks.Right.X * speed;
this.cameraTarget.Y += gamePadState.ThumbSticks.Right.Y * speed;
if (keyState.IsKeyDown(Keys.A))
{
this.cameraTarget.X -= speed;
}
if (keyState.IsKeyDown(Keys.S))
{
this.cameraTarget.X += speed;
}
if (keyState.IsKeyDown(Keys.Z))
{
this.cameraTarget.Y -= speed;
}
if (keyState.IsKeyDown(Keys.W))
{
this.cameraTarget.Y += speed;
}
if (this.autoMode == 3)
{
this.cameraTarget.X = (float)Math.Sin(gameTime.TotalGameTime.TotalSeconds) * 10.0f;
}
if (this.autoMode == 4)
{
this.cameraTarget.Y = (float)Math.Sin(gameTime.TotalGameTime.TotalSeconds) * 10.0f;
}
// カメラの上方方向を回転させる
this.cameraUpVectorRotate -= gamePadState.Triggers.Left * speed * 0.2f;
this.cameraUpVectorRotate += gamePadState.Triggers.Right * speed * 0.2f;
if (keyState.IsKeyDown(Keys.X))
{
this.cameraUpVectorRotate -= speed * 0.2f;
}
if (keyState.IsKeyDown(Keys.C))
{
this.cameraUpVectorRotate += speed * 0.2f;
}
if (this.autoMode == 5)
{
this.cameraUpVectorRotate = (float)gameTime.TotalGameTime.TotalSeconds;
}
// 登録された GameComponent を更新する
base.Update(gameTime);
}
<summary>
描画処理を行うメソッド
</summary>
<param name="gameTime">このメソッドが呼ばれたときのゲーム時間</param>
protected override void Draw(GameTime gameTime)
{
// 画面を指定した色でクリアします
this.GraphicsDevice.Clear(Color.CornflowerBlue);
// 深度バッファを有効にする
this.GraphicsDevice.DepthStencilState = DepthStencilState.Default;
// ビューマトリックス作成
Matrix view = Matrix.CreateLookAt(
this.cameraPosition,
this.cameraTarget,
Vector3.Transform(Vector3.Up,
Matrix.CreateRotationZ(this.cameraUpVectorRotate))
);
// プロジェクションマトリックス作成
Matrix projection = Matrix.CreatePerspectiveFieldOfView(
MathHelper.PiOver4,
(float)this.GraphicsDevice.Viewport.Width /
(float)this.GraphicsDevice.Viewport.Height,
1.0f,
100.0f
);
// ボックスモデル /////
foreach (ModelMesh mesh in this.box.Meshes)
{
foreach (BasicEffect effect in mesh.Effects)
{
// ライトの設定
effect.EnableDefaultLighting();
// ボックスの位置をカメラの注視点に合わせる
effect.World = Matrix.CreateTranslation(this.cameraTarget);
// ビューマトリックスを設定
effect.View = view;
// プロジェクションマトリックス設定
effect.Projection = projection;
}
mesh.Draw();
}
// XYZ軸モデル /////
foreach (ModelMesh mesh in this.xyz.Meshes)
{
foreach (BasicEffect effect in mesh.Effects)
{
// ライトの設定
effect.EnableDefaultLighting();
// 原点に配置
effect.World = Matrix.Identity;
// ビューマトリックスを設定
effect.View = view;
// プロジェクションマトリックス設定
effect.Projection = projection;
}
mesh.Draw();
}
// スプライトの描画準備
this.spriteBatch.Begin();
// カメラの情報を表示
this.spriteBatch.DrawString(this.font,
"CameraPosition : {" +
this.cameraPosition.X.ToString("f2") + ", " +
this.cameraPosition.Y.ToString("f2") + "}" + Environment.NewLine +
"CameraTarget : {" +
this.cameraTarget.X.ToString("f2") + ", " +
this.cameraTarget.Y.ToString("f2") + "}" + Environment.NewLine +
"CameraUpVectorRotate : " + this.cameraUpVectorRotate.ToString("f2") + Environment.NewLine +
"MousePressAutoMode : " + this.autoMode,
new Vector2(20, 20), Color.White);
// スプライトの一括描画
this.spriteBatch.End();
// 登録された DrawableGameComponent を描画する
base.Draw(gameTime);
}
}
}