Getting Started with XNA Game Studio 3.0 to develop video games
by Uditha Sampath Bandara
Part VIII.
This month we`ll discuss about code and steps to use 3D coalition in a PC game.
First you need to add 3d models and a 2d image to the content folder in a new XNA project.
Then you are able to write the code.
In the Game1.cs file initialize these variables.
Model model, colide_car, land; // Initialize 3d model variables
Texture2D sunset; //Initialize texture variable
KeyboardState lastKeyboardState;// Initialize keyboard
float distance= 0.0f; // set distance to zero
float distance_left = 0.0f; // set distance_left to zero
bool active = false; // set active to false
float change_dir = 0.0f; // set change_dir to zero;
Now in the LoadContent() method write code for loading the assest
model = Content.Load<Model>("car"); //load the player car model
colide_car = Content.Load<Model>("car");//load the AI car model
land = Content.Load<Model>("floor"); //load the land model
sunset =
Content.Load<Texture2D>("sunset");//load
the 2d
Then in theUpdate() method you can write this code segment.
lastKeyboardState
= Keyboard.GetState();// get the user keyboard
if
(lastKeyboardState.IsKeyDown(Keys.Up)) //chack whether user
{
distance = distance + 2.8f; // increase distance
}
if
(lastKeyboardState.IsKeyDown(Keys.Down))//chack whether user
{
distance = distance - 2.8f; //decrease distance
}
if
(lastKeyboardState.IsKeyDown(Keys.Left))//chack whether user
{
distance_left = distance_left + 0.03f; // increase distance_left
}
if (lastKeyboardState.IsKeyDown(Keys.Right))//chack whether user pressRIGHT
{
distance_left = distance_left - 0.03f;//decrease distance_left
}
In the Draw () method you can see the Changes by drawing the images and models.
GraphicsDevice device = graphics.GraphicsDevice; //set the device to the current graphic device
Viewport viewport = device.Viewport; // set the viewport to the current device viewport
spriteBatch.Begin(); //begin the spitebatch process
spriteBatch.Draw(sunset, new Vector2(0.0f, 0.0f), Color.White); //draw the image in 0,0 location
spriteBatch.End(); //end the spite batch process
float aspectRatio = (float)viewport.Width / (float)viewport.Height; //set the aspectRatio
// Create camera matrices with substracting distance
Matrix world = Matrix.CreateRotationY(-20.42f) *
Matrix.CreateTranslation(2000.0f-distance, 0.0f, 0.0f)
*Matrix.CreateRotationY(distance_left);
// Create view
Matrix view = Matrix.CreateLookAt(new Vector3(3750,800, 60),
new Vector3(0, 300, 0),Vector3.Up);
// Create projection
Matrix projection = Matrix.CreatePerspectiveFieldOfView(1, aspectRatio, 1, 100000);
// create transform Matrix
Matrix[] transforms = new Matrix[model.Bones.Count];
model.CopyAbsoluteBoneTransformsTo(transforms);
// Draw the main car.
foreach (ModelMesh mesh inmodel.Meshes)
{
foreach (BasicEffect effect inmesh.Effects)
{
effect.World = transforms[mesh.ParentBone.Index] * world;
effect.View = view;
effect.Projection = projection;
effect.LightingEnabled = true;
effect.DirectionalLight0.Enabled = true;
effect.DirectionalLight0.Direction = Vector3.Left; //set the directinal lighting
effect.DirectionalLight0.DiffuseColor = Vector3.One;
GraphicsDevice.RenderState.DepthBufferEnable = true; //set the grapics card rendering to depthbuffer enable
GraphicsDevice.RenderState.AlphaBlendEnable = false;
GraphicsDevice.RenderState.AlphaTestEnable = false;
}
mesh.Draw(); // draw the player car
}
// For the AI car add the change_dir
Matrix world2 = Matrix.CreateRotationY(0.42f) *
Matrix.CreateTranslation(100.0f,0.0f, 0.0f+change_dir);
Matrix[] transforms2 = new Matrix[colide_car.Bones.Count];
colide_car.CopyAbsoluteBoneTransformsTo(transforms2);
// Draw the AI car.
foreach (ModelMesh mesh in colide_car.Meshes)
{
foreach (BasicEffect effect in mesh.Effects)
{
effect.World = transforms2[mesh.ParentBone.Index] * world2;
effect.View = view;
effect.Projection = projection;
effect.LightingEnabled = true;
effect.DirectionalLight0.Enabled = true;
effect.DirectionalLight0.Direction = Vector3.Left; //set the directinal lighting
effect.DirectionalLight0.DiffuseColor = Vector3.One;
GraphicsDevice.RenderState.DepthBufferEnable = true; //set the grapics card rendering to depthbuffer enable
GraphicsDevice.RenderState.AlphaBlendEnable = false;
GraphicsDevice.RenderState.AlphaTestEnable = false;
}
mesh.Draw(); //draw the AI car
}
#region chack coolition
//collition detection
//Create a BoundingSphere for car1 with its center point and meshes BoundingSphere radies
BoundingSphere car1 = new BoundingSphere(new Vector3(2000.0f - distance, 0.0f, 0.0f), model.Meshes[0].BoundingSphere.Radius * 0.95f);
//Create a BoundingSphere for car2 with its center point and mesh BoundingSphere radies
BoundingSphere car2 = new BoundingSphere(new Vector3(100.0f, 0.0f, 0.0f+change_dir),
colide_car.Meshes[0].BoundingSphere.Radius*0.95f);
if (car2.Intersects(car1)) //chack whather car1 and AI car(car2) intersects
{
active = true; //then set active true
}
if (active == false) //when active false
{
change_dir = 0.0f; //set change_dir to zero
}
else
{
change_dir = change_dir + 4.8f; // or increment the value
}
#endregion
#region draw land
//set the transforms Matrix
Matrix[] transforms3 = new Matrix[land.Bones.Count];
land.CopyAbsoluteBoneTransformsTo(transforms3);
foreach (ModelMesh mesh in land.Meshes)
{
foreach (BasicEffect effect in mesh.Effects)
{
effect.World = transforms[mesh.ParentBone.Index] * Matrix.CreateRotationX(4.7f) *Matrix.CreateTranslation(400.0f,0.0f,0.0f);
effect.View = view;
effect.Projection = projection;
graphics.GraphicsDevice.RenderState.DepthBufferEnable = true;
//set the grapics card rendering to depthbuffer enable
}
mesh.Draw(); // Draw the land.
}
#endregion
Now you can run the project by pressing F5 or by clicking the run button.
Final code of Game1.cs
/*
content created by -uditha sampath bandara
udithamail@yahoo.com
uditha.wordpress.com
*/
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;
using Microsoft.Xna.Framework.Net;
using Microsoft.Xna.Framework.Storage;
namespace ligting_car_xna_3._0
{
/// <summary>
/// This is the main type for your game
/// </summary>
public class Game1 : Microsoft.Xna.Framework.Game
{
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
Model model, colide_car, land; // Initialize 3d model variables
Texture2D sunset; // Initialize texture variable
KeyboardState lastKeyboardState;// Initialize keyboard
float distance= 0.0f; // set distance to zero
float distance_left = 0.0f; // set distance_left to zero
bool active = false; // set active to false
float change_dir = 0.0f; // set change_dir to zero;
public Game1()
{
Content.RootDirectory = "Content";
graphics = new GraphicsDeviceManager(this);
}
/// <summary>
/// Allows the game to perform any initialization it needs to before starting to run.
/// This is where it can query for any required services and load any non-graphic
/// related content. Calling base.Initialize will enumerate through any components
/// and initialize them as well.
/// </summary>
protected override void Initialize()
{
base.Initialize();
}
/// <summary>
/// LoadContent will be called once per game and is the place to load
/// all of your content.
/// </summary>
protected override void LoadContent()
{
// Create a new SpriteBatch, which can be used to draw textures.
spriteBatch = new SpriteBatch(GraphicsDevice);
model = Content.Load<Model>("car"); //load the player car model
colide_car = Content.Load<Model>("car"); //load the AI car model
land = Content.Load<Model>("floor"); //load the land model
sunset = Content.Load<Texture2D>("sunset"); //load the 2d background
}
protected override void UnloadContent()
{
}
//<summary>
//Allows the game to run logic such as updating the world,
//checking for collisions, gathering input, and playing audio.
//</summary>
// <param name="gameTime">Provides a snapshot of timing values.</param>
protected override void Update(GameTime gameTime)
{
//Allows the game to exit
if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
this.Exit();
lastKeyboardState = Keyboard.GetState(); // get the user keyboard state
if (lastKeyboardState.IsKeyDown(Keys.Up)) //chack whether user press UP
{
distance = distance + 2.8f; // increase distance
}
if (lastKeyboardState.IsKeyDown(Keys.Down))//chack whether user press DOWN
{
distance = distance - 2.8f; //decrease distance
}
if (lastKeyboardState.IsKeyDown(Keys.Left))//chack whether user press LEFT
{
distance_left = distance_left + 0.03f; // increase distance_left
}
if (lastKeyboardState.IsKeyDown(Keys.Right))//chack whether user press RIGHT
{
distance_left = distance_left - 0.03f;//decrease distance_left
}
base.Update(gameTime);
}
/// <summary>
/// This is called when the game should draw itself.
/// </summary>
/// <param name="gameTime">Provides a snapshot of timing values.</param>
protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(Color.Black); // clear the graphic device
GraphicsDevice device = graphics.GraphicsDevice; //set the device to the current graphic device
Viewport viewport = device.Viewport; // set the viewport to the current device viewport
spriteBatch.Begin(); //begin the spitebatch process
spriteBatch.Draw(sunset, new Vector2(0.0f, 0.0f), Color.White); //draw the image in 0,0 location
spriteBatch.End(); //end the spite batch process
float aspectRatio = (float)viewport.Width / (float)viewport.Height; //set the aspectRatio
// Create camera matrices with substracting distance
Matrix world = Matrix.CreateRotationY(-20.42f) * Matrix.CreateTranslation(2000.0f-distance, 0.0f, 0.0f)
*Matrix.CreateRotationY(distance_left);
// Create view
Matrix view = Matrix.CreateLookAt(new Vector3(3750,800, 60),
new Vector3(0, 300, 0),
Vector3.Up);
// Create projection
Matrix projection = Matrix.CreatePerspectiveFieldOfView(1, aspectRatio,
1, 100000);
// create transform Matrix
Matrix[] transforms = new Matrix[model.Bones.Count];
model.CopyAbsoluteBoneTransformsTo(transforms);
// Draw the main car.
foreach (ModelMesh mesh in model.Meshes)
{
foreach (BasicEffect effect in mesh.Effects)
{
effect.World = transforms[mesh.ParentBone.Index] * world;
effect.View = view;
effect.Projection = projection;
effect.LightingEnabled = true;
effect.DirectionalLight0.Enabled = true;
effect.DirectionalLight0.Direction = Vector3.Left; //set the directinal lighting
effect.DirectionalLight0.DiffuseColor = Vector3.One;
GraphicsDevice.RenderState.DepthBufferEnable = true; //set the grapics card rendering to depthbuffer enable
GraphicsDevice.RenderState.AlphaBlendEnable = false;
GraphicsDevice.RenderState.AlphaTestEnable = false;
}
mesh.Draw(); // draw the player car
}
// For the AI car add the change_dir
Matrix world2 = Matrix.CreateRotationY(0.42f) * Matrix.CreateTranslation(100.0f, 0.0f, 0.0f+change_dir);
Matrix[] transforms2 = new Matrix[colide_car.Bones.Count];
colide_car.CopyAbsoluteBoneTransformsTo(transforms2);
// Draw the AI car.
foreach (ModelMesh mesh in colide_car.Meshes)
{
foreach (BasicEffect effect in mesh.Effects)
{
effect.World = transforms2[mesh.ParentBone.Index] * world2;
effect.View = view;
effect.Projection = projection;
effect.LightingEnabled = true;
effect.DirectionalLight0.Enabled = true;
effect.DirectionalLight0.Direction = Vector3.Left; //set the directinal lighting
effect.DirectionalLight0.DiffuseColor = Vector3.One;
GraphicsDevice.RenderState.DepthBufferEnable = true; //set the grapics card rendering to depthbuffer enable
GraphicsDevice.RenderState.AlphaBlendEnable = false;
GraphicsDevice.RenderState.AlphaTestEnable = false;
}
mesh.Draw(); //draw the AI car
}
#region chack coolition
//collition detection
//Create a BoundingSphere for car1 with its center point and meshes BoundingSphere radies
BoundingSphere car1 = new BoundingSphere(new Vector3(2000.0f - distance, 0.0f, 0.0f), model.Meshes[0].BoundingSphere.Radius * 0.95f);
//Create a BoundingSphere for car2 with its center point and mesh BoundingSphere radies
BoundingSphere car2 = new BoundingSphere(new Vector3(100.0f, 0.0f, 0.0f+change_dir), colide_car.Meshes[0].BoundingSphere.Radius*0.95f);
if (car2.Intersects(car1)) //chack whather car1 and AI car(car2) intersects
{
active = true; //then set active true
}
if (active == false) //when active false
{
change_dir = 0.0f; //set change_dir to zero
else
{
change_dir = change_dir + 4.8f; // or increment the value
#endregion
#region draw land
//set the transforms Matrix
Matrix[] transforms3 = new Matrix[land.Bones.Count];
land.CopyAbsoluteBoneTransformsTo(transforms3);
foreach (ModelMesh mesh in land.Meshes)
{
foreach (BasicEffect effect in mesh.Effects)
{
effect.World = transforms[mesh.ParentBone.Index] * Matrix.CreateRotationX(4.7f)
*Matrix.CreateTranslation(400.0f,0.0f,0.0f);
effect.View = view;
effect.Projection = projection;
graphics.GraphicsDevice.RenderState.DepthBufferEnable = true;
//set the grapics card rendering to depthbuffer enable
}
}
#endregion
base.Draw(gameTime);
}
}
}
This is the end of the using 3d coalition in a PC game tutorial.
Also source project is
attached with this article.(http://digit.lk/downloads/
Form the next tutorial you`ll learn about using VB.NET as the programming language in a XNA game.
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