Projective Coordinate Transformation
summary
Manipulating the parameters of the projective 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 | ||
---|---|---|---|---|
Changing the viewing angle | ↑↓ | Left stick (up and down) | Left button (automatic change, operation switching) | - |
Changing the Aspect Ratio | ←→ | trigger | Left button (automatic change, operation switching) | - |
Changing the Rear Clipping Plane | A,Z | Right stick (up and down) | Left button (automatic change, operation switching) | - |
substance
About Projective Coordinate Transformations
Please refer to the following page for an overview of projective coordinate transformations.
field
Four parameters are prepared so that the parameters used for projective coordinate conversion can be manipulated: "viewing angle", "aspect ratio", and "clipping position (forward, backward)".
<summary>
視野角(radian)
</summary>
private float angle = 45.0f;
<summary>
アスペクト比
</summary>
private float aspect = 1.0f;
<summary>
手前のクリッピング位置
</summary>
private float nearLimit = 1.0f;
<summary>
奥のクリッピング位置
</summary>
private float farLimit = 100.0f;
Working with Parameters
In the Game.Update method, we use the keyboard and controller to manipulate each parameter. 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)
Set the viewing angle in the range of "0 < x < π". (In the example, when we create the projective transformation, we convert it from degree to radian, so here it is "0 < x < 180.")
The aspect ratio should not be less than or equal to 0.
The forward and backward clip positions should not be reversed. It must not be set to 0 or less.
GamePadState gamePadState = GamePad.GetState(PlayerIndex.One);
// 視野角を増減させる /////
float angleSpeed = 0.05f;
this.angle += gamePadState.ThumbSticks.Left.Y * this.angle * angleSpeed;
// 視野角は0~180度までの範囲とする
if (this.angle <= 0.0f)
{
this.angle = 0.0001f;
}
else if (this.angle >= 180.0f)
{
this.angle = 179.9999f;
}
//// アスペクト比 /////
float aspectSpeed = 0.01f;
this.aspect -= gamePadState.Triggers.Left * this.aspect * aspectSpeed;
this.aspect += gamePadState.Triggers.Right * this.aspect * aspectSpeed;
//// 奥のクリッピング位置 /////
float clipSpeed = 0.05f;
this.farLimit += gamePadState.ThumbSticks.Right.Y * this.farLimit * clipSpeed;
if (this.farLimit <= this.nearLimit)
{
// 手前のクリッピング位置よりも手前に来てはいけない
this.farLimit = this.nearLimit + 0.0001f;
}
Creating a Projection Matrix
The projection matrix is created by setting each parameter in the "Matrix.CreatePerspectiveFieldOfView" method.
The first argument is the viewing angle in radians. In the sample, the degree unit is converted to radian using the "MathHelper.ToRadians" method.
The second argument specifies the aspect ratio (aspect ratio), the third argument specifies the forward clipping position, and the fourth argument specifies the back clipping position.
// プロジェクションマトリックスを作成
Matrix projection = Matrix.CreatePerspectiveFieldOfView(
MathHelper.ToRadians(this.angle),
this.aspect,
this.nearLimit,
this.farLimit
);
Matrix.CreatePerspectiveFieldOfView
method
Creates a perspective projection matrix based on the settings of the view field.
fieldOfView | float | Viewing angle. Specified in radian units. |
aspectRatio | float | Aspect ratio (aspect ratio). Normally, you specify a value for "View Width ÷ Height" |
nearPlaneDistance | float | Forward clip position. Objects in front of this position are not drawn. |
farPlaneDistance | float | Rear clip position. Objects beyond this position are not drawn. |
Return Values | Matrix | Returns a perspective projection matrix |
Set of projection matrices
A projection matrix is set for each effect.
foreach (ModelMesh mesh in this.model.Meshes)
{
foreach (BasicEffect effect in mesh.Effects)
{
// プロジェクションマトリックスを設定
effect.Projection = projection;
}
// モデルを描画
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 ProjectionMatrix
{
<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>
モデル
</summary>
private Model model = null;
<summary>
視野角(radian)
</summary>
private float angle = 45.0f;
<summary>
アスペクト比
</summary>
private float aspect = 1.0f;
<summary>
手前のクリッピング位置
</summary>
private float nearLimit = 1.0f;
<summary>
奥のクリッピング位置
</summary>
private float farLimit = 100.0f;
<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");
// モデルを作成
this.model = this.Content.Load<Model>("Model");
foreach (ModelMesh mesh in this.model.Meshes)
{
foreach (BasicEffect effect in mesh.Effects)
{
// デフォルトのライト適用
effect.EnableDefaultLighting();
// ビューマトリックスをあらかじめ設定
effect.View = Matrix.CreateLookAt(
new Vector3(3.0f, 3.0f, 6.0f),
Vector3.Zero,
Vector3.Up
);
}
}
// アスペクト比の初期値を設定
this.aspect = (float)this.GraphicsDevice.Viewport.Width / this.GraphicsDevice.Viewport.Height;
}
<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) % 4;
}
this.isMousePressed = mouseState.LeftButton == ButtonState.Pressed;
// 視野角を増減させる /////
float angleSpeed = 0.05f;
this.angle += gamePadState.ThumbSticks.Left.Y * this.angle * angleSpeed;
if (keyState.IsKeyDown(Keys.Down))
{
this.angle -= this.angle * angleSpeed;
}
if (keyState.IsKeyDown(Keys.Up))
{
this.angle += this.angle * angleSpeed;
}
if (this.autoMode == 1)
{
this.angle = (float)(Math.Sin(gameTime.TotalGameTime.TotalSeconds) + 1.0f) * 90.0f;
}
// 視野角は0~180度までの範囲とする
if (this.angle <= 0.0f)
{
this.angle = 0.0001f;
}
else if (this.angle >= 180.0f)
{
this.angle = 179.9999f;
}
//// アスペクト比 /////
float aspectSpeed = 0.01f;
this.aspect -= gamePadState.Triggers.Left * this.aspect * aspectSpeed;
this.aspect += gamePadState.Triggers.Right * this.aspect * aspectSpeed;
if (keyState.IsKeyDown(Keys.Left))
{
this.aspect -= this.aspect * aspectSpeed;
}
if (keyState.IsKeyDown(Keys.Right))
{
this.aspect += this.aspect * aspectSpeed;
}
if (this.autoMode == 2)
{
this.aspect = (float)(Math.Sin(gameTime.TotalGameTime.TotalSeconds) + 1.0f) * 2.0f;
}
//// 奥のクリッピング位置 /////
float clipSpeed = 0.05f;
this.farLimit += gamePadState.ThumbSticks.Right.Y * this.farLimit * clipSpeed;
if (keyState.IsKeyDown(Keys.Z))
{
this.farLimit -= this.farLimit * clipSpeed;
}
if (keyState.IsKeyDown(Keys.A))
{
this.farLimit += this.farLimit * clipSpeed;
}
if (this.autoMode == 3)
{
this.farLimit = (float)(Math.Sin(gameTime.TotalGameTime.TotalSeconds) + 1.0f) * 8.0f;
}
if (this.farLimit <= this.nearLimit)
{
// 手前のクリッピング位置よりも手前に来てはいけない
this.farLimit = this.nearLimit + 0.0001f;
}
// 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);
// プロジェクションマトリックスを作成
Matrix projection = Matrix.CreatePerspectiveFieldOfView(
MathHelper.ToRadians(this.angle),
this.aspect,
this.nearLimit,
this.farLimit
);
foreach (ModelMesh mesh in this.model.Meshes)
{
foreach (BasicEffect effect in mesh.Effects)
{
// プロジェクションマトリックスを設定
effect.Projection = projection;
}
// モデルを描画
mesh.Draw();
}
// スプライトの描画準備
this.spriteBatch.Begin();
// テキストをスプライトとして描画する
this.spriteBatch.DrawString(this.font,
"Angle : " + this.angle + Environment.NewLine +
"Aspect : " + this.aspect + Environment.NewLine +
"NearLimit : " + this.nearLimit + Environment.NewLine +
"FarLimit : " + this.farLimit + Environment.NewLine +
"MousePressAutoMode : " + this.autoMode,
new Vector2(50, 50), 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);
}
}
}