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Rotate your terrain using the keyboard |
Using XNA, it is very easy to read in the current state of your keyboard. The correct libraries, Microsoft.Xna.Framework.Input, are already linked to by default when you’ve started your XNA project, so we can immediately move on to the code that reads in the keyboard input.
Add this bit of code to your Update method, which is called 60 times per second:
KeyboardState keyState = Keyboard.GetState();
if (keyState.IsKeyDown(Keys.Delete))
angle += 0.05f;
if (keyState.IsKeyDown(Keys.PageDown))
angle -= 0.05f;
Here you put the current state of the keyboard in a variable 'keyState'. Using this variable, you can immediately read out which keys are currently being pressed! When the user presses the Delete or PageDown key, the value of the ‘angle’ variable will be adjusted.
In our Draw method, we need to make sure that this rotation is taken into account by our World matrix:
Matrix worldMatrix = Matrix.CreateTranslation(-terrainWidth / 2.0f, 0, terrainHeight / 2.0f) * Matrix.CreateRotationY(angle);
The terrain is rotated around the Y Up axis before it is moved to the (0,0,0) 3D origin.
Et voila! When you run the code, you can rotate your terrain simply by pressing the Delete and PageDown buttons!
Click here to go to the forum on this chapter!
Or click on one of the topics on this chapter to go there:
Input with JOYPAD
Hi,
Thanks for your work
Would it possible t...Problem with LoaderLock and the keyboard
I was going through everything fine until I got to...Inline code vs end of page
Hi Riemer! I love the tutorials. I know website m...
You can try these exercises to practice what you've learned:
Add some code that reads in the Arrow keys. Adjust your world matrix so the terrain is moved into the direction of the Arrow key being pressed.
The code for our rotating terrain:
using System;
using System.Collections.Generic;
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.Net;
using Microsoft.Xna.Framework.Storage;
namespace XNAtutorial
{
public class Game1 : Microsoft.Xna.Framework.Game
{
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
GraphicsDevice device;
Effect effect;
VertexPositionColor[] vertices;
VertexDeclaration myVertexDeclaration;
int[] indices;
Matrix viewMatrix;
Matrix projectionMatrix;
private int terrainWidth;
private int terrainHeight;
private float[,] heightData;
float angle = 0;
public Game1()
{
graphics = new GraphicsDeviceManager(this);
Content.RootDirectory = "Content";
}
protected override void Initialize()
{
graphics.PreferredBackBufferWidth = 500;
graphics.PreferredBackBufferHeight = 500;
graphics.IsFullScreen = false;
graphics.ApplyChanges();
Window.Title = "Riemer's XNA Tutorials -- Series 1";
base.Initialize();
}
protected override void LoadContent()
{
device = graphics.GraphicsDevice;
spriteBatch = new SpriteBatch(GraphicsDevice);
effect = Content.Load<Effect>
("effects");
Texture2D heightMap = Content.Load<Texture2D>
("heightmap"); LoadHeightData(heightMap);
SetUpVertices();
SetUpCamera();
SetUpIndices();
}
private void SetUpVertices()
{
vertices = new VertexPositionColor[terrainWidth * terrainHeight];
for (int x = 0; x < terrainWidth; x++)
{
for (int y = 0; y < terrainHeight; y++)
{
vertices[x + y * terrainWidth].Position = new Vector3(x, heightData[x, y], -y);
vertices[x + y * terrainWidth].Color = Color.White;
}
}
myVertexDeclaration = new VertexDeclaration(device, VertexPositionColor.VertexElements);
}
private void SetUpIndices()
{
indices = new int[(terrainWidth - 1) * (terrainHeight - 1) * 6];
int counter = 0;
for (int y = 0; y < terrainHeight - 1; y++)
{
for (int x = 0; x < terrainWidth - 1; x++)
{
int lowerLeft = x + y*terrainWidth;
int lowerRight = (x + 1) + y*terrainWidth;
int topLeft = x + (y + 1) * terrainWidth;
int topRight = (x + 1) + (y + 1) * terrainWidth;
indices[counter++] = topLeft;
indices[counter++] = lowerRight;
indices[counter++] = lowerLeft;
indices[counter++] = topLeft;
indices[counter++] = topRight;
indices[counter++] = lowerRight;
}
}
}
private void SetUpCamera()
{
viewMatrix = Matrix.CreateLookAt(new Vector3(60, 80, -80), new Vector3(0, 0, 0), new Vector3(0, 1, 0));
projectionMatrix = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4, device.Viewport.AspectRatio, 1.0f, 300.0f);
}
private void LoadHeightData(Texture2D heightMap)
{
terrainWidth = heightMap.Width;
terrainHeight = heightMap.Height;
Color[] heightMapColors = new Color[terrainWidth * terrainHeight];
heightMap.GetData(heightMapColors);
heightData = new float[terrainWidth, terrainHeight];
for (int x = 0; x < terrainWidth; x++)
for (int y = 0; y < terrainHeight; y++)
heightData[x, y] = heightMapColors[x + y * terrainWidth].R / 5.0f;
}
protected override void UnloadContent()
{
}
protected override void Update(GameTime gameTime)
{
if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
this.Exit();
KeyboardState keyState = Keyboard.GetState();
if (keyState.IsKeyDown(Keys.Delete))
angle += 0.05f;
if (keyState.IsKeyDown(Keys.PageDown))
angle -= 0.05f;
base.Update(gameTime);
}
protected override void Draw(GameTime gameTime)
{
device.Clear(Color.Black);
device.RenderState.CullMode = CullMode.None;
device.RenderState.FillMode = FillMode.WireFrame;
Matrix worldMatrix = Matrix.CreateTranslation(-terrainWidth / 2.0f, 0, terrainHeight / 2.0f) * Matrix.CreateRotationY(angle);
effect.CurrentTechnique = effect.Techniques["Colored"];
effect.Parameters["xView"].SetValue(viewMatrix);
effect.Parameters["xProjection"].SetValue(projectionMatrix);
effect.Parameters["xWorld"].SetValue(worldMatrix);
effect.Begin();
foreach (EffectPass pass in effect.CurrentTechnique.Passes)
{
pass.Begin();
device.VertexDeclaration = myVertexDeclaration;
device.DrawUserIndexedPrimitives(PrimitiveType.TriangleList, vertices, 0, vertices.Length, indices, 0, indices.Length / 3);
pass.End();
}
effect.End();
base.Draw(gameTime);
}
}
}
- Website design & XNA + DirectX code : Riemer Grootjans -
©2003 - 2008 Riemer Grootjans
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2007 - 2008 MVP Award
DirectX - XNA
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