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As you have probably already guessed, this chapter we’re going to detect when our plane has collided with an element of the scene – this far, our 3D city.
To do this, we’re going to model our airplane as a sphere, which we be good enough for the purpose. Remember we already know the radius of the sphere, as it is stored in the spacemeshradius variable, we filled when loading the mesh.
By using some very basic maths, it should be possible to detect collisions. To do this, we’re going to create a new method, called CheckCollision. This function will return an integer – 0 meaning no collision, 1 meaning a collision with an object of the 3D city and a 2 meaning the plane has gone too high. Of course, the method need the position of our airplane, as well as its radius. Start with this code:
private int CheckCollision(Vector3 position, float radius)
{
if (position.Z - radius < 0) return 1;
if (position.Z + radius > 15) return 2;
if ((position.X < -10) || (position.X > WIDTH+10)) return 2;
if ((position.Y < -10) || (position.Y > HEIGHT+10)) return 2;
return 0;
}
We’ve already discussed the interface corresponding to the first line. Inside the method, we first check if our plane hasn’t crashed into the ground. Position.Z corresponds to the center of our plane, we need to subtract the radius from it if we want to know the lowest point of our airplane. If this bottom point is lower than 0, our plane has crashed. Too bad, and the method will return value 1. Exactly the same check occurs for checking whether the plane has gone too high. In that case, however, a 2 is returned instead of a 1. This way, the calling method is able to know what kind of ‘collision’ has occurred, and subtract points accordingly. This way, you’ll be able to subtract the player more points when he’s crashed into the floor than when he’s flown too high.
The next two lines simply perform a similar check to see whether the player hasn’t flown too far away from the city. If that’s the case, a 2 will be returned, again indicating that the ‘collision’ was not really a crash. If none of the checks turn out to be positive, a 0 is returned, meaning no collision of any kind has happened.
Now it’s time to check for collisions between the plane and the buildings. Add these lines before the ‘return 0’ line:
if ((position.X - radius > 0) && (position.X + radius < WIDTH) && (position.Y - radius> 0) && (position.Y + radius < HEIGHT))
{
if (position.Z - radius < buildingheights[int_Floorplan[(int)position.X, (int)position.Y]]) return 1;
}
The middle line simply checks whether the lowest point of the plane isn’t lower than the top of the building at that position. Remember the int_Floorplan contains the type of building at that position, while we can find the corresponding height in the buildingheights variable. Notice, however, that we’re accessing the int_Floorplan variable, which means the X and Y coordinates of our plane must not be smaller than 0 or larger than the dimension of this variable. It is exactly this condition that is being check by the first line.
The only thing we have to do, is react to a collision. So add these lines in your OnPaint method, immediately after you’ve updated the position of our plane:
if (CheckCollision(spacemeshposition, spacemeshradius) > 0)
{
spacemeshposition = new Vector3(8, 2, 1);
spacemeshangles = new Vector3(0, 0, 0);
gamespeed /= 1.1f;
score /= 2;
}
The first line checks whether a collision has occurred. If this is the case, the position and angles of our plane will be reset to the starting conditions. Of course, we want to punish the player a little more than simply replacing his/her plane. So every time the plane crashes, the speed of the game will be turned down a notch! Also, every time the plane crashes, the score halves.
To make this runnable, we have to declare this score variable, so put this at the top of your code:
private double score = 0;
That should do the job! Run the program and crash as fast as possible. Your plane should be repositioned to your starting position, and after a few crashes you should notice the game speed decreasing. Have fun!
Click here to go to the forum on this chapter!
Or click on one of the topics on this chapter to go there:
Walking over the terrain
Hey,
I've sorta thought about a bunch of diffe...
Well that image didn’t differ much from last chapter’s image … but this time we’ve implemented collision detection! What’s the next most disturbing aspect.. Maybe that damned darkslateblueish background! Let’s do something about that .. in the next chapter.
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using Microsoft.DirectX;
using Microsoft.DirectX.Direct3D;
using D3D = Microsoft.DirectX.Direct3D;
using Microsoft.DirectX.DirectInput;
using DI = Microsoft.DirectX.DirectInput;
namespace DirectX_Tutorial
{
public class WinForm : System.Windows.Forms.Form
{
private int[,] int_Floorplan;
private int WIDTH;
private int HEIGHT;
private int differentbuildings = 5;
private float gamespeed = 0.04f;
private int[] buildingheights = new int[] { 0, 10, 1, 3, 2, 5 };
private System.ComponentModel.Container components = null;
private D3D.Device device;
private Texture scenerytexture;
private Material material;
private CustomVertex.PositionNormalTextured[] verticesarray;
ArrayList verticeslist = new ArrayList();
private Mesh spacemesh;
private Material[] spacemeshmaterials;
private Texture[] spacemeshtextures;
private float spacemeshradius;
private float scaling = 0.0005f;
private Vector3 spacemeshposition = new Vector3(8, 2, 1);
private Vector3 spacemeshangles = new Vector3(0, 0, 0);
private DI.Device keyb;
private double score = 0;
public WinForm()
{
InitializeComponent();
this.SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.Opaque, true);
}
public void InitializeDevice()
{
PresentParameters presentParams = new PresentParameters();
presentParams.Windowed = true;
presentParams.SwapEffect = SwapEffect.Discard;
presentParams.AutoDepthStencilFormat = DepthFormat.D16;
presentParams.EnableAutoDepthStencil = true;
device = new D3D.Device(0, D3D.DeviceType.Hardware, this, CreateFlags.SoftwareVertexProcessing, presentParams);
device.RenderState.Lighting = true;
device.Lights[0].Type = LightType.Directional;
device.Lights[0].Diffuse = Color.White;
device.Lights[0].Direction = new Vector3(1, 1, -1);
device.Lights[0].Update();
device.Lights[0].Enabled = true;
device.Lights[1].Type = LightType.Directional;
device.Lights[1].Diffuse = Color.White;
device.Lights[1].Direction = new Vector3(-1, -1, -1);
device.Lights[1].Update();
device.Lights[1].Enabled = true;
}
protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)
{
ReadUserInput(gamespeed);
UpdatePosition(ref spacemeshposition, spacemeshangles, gamespeed);
if (CheckCollision(spacemeshposition, spacemeshradius) > 0)
{
spacemeshposition = new Vector3(8, 2, 1);
spacemeshangles = new Vector3(0, 0, 0);
gamespeed /= 1.1f;
score /= 2;
}
device.Clear(ClearFlags.Target | ClearFlags.ZBuffer, Color.DarkSlateBlue, 1.0f, 0);
device.BeginScene();
device.RenderState.Ambient = Color.DarkGray;
device.Transform.World = Matrix.Translation(-(float)spacemeshposition.X, -(float)spacemeshposition.Y, -(float)spacemeshposition.Z) * Matrix.RotationYawPitchRoll((float)spacemeshangles.X, (float)spacemeshangles.Y, (float)spacemeshangles.Z);
device.VertexFormat = CustomVertex.PositionNormalTextured.Format;
device.SetTexture(0, scenerytexture);
device.DrawUserPrimitives(PrimitiveType.TriangleList, verticeslist.Count / 3, verticesarray);
device.Transform.World = Matrix.Scaling(scaling, scaling, scaling) * Matrix.RotationX((float)Math.PI / 2);
DrawMesh(spacemesh, spacemeshmaterials, spacemeshtextures);
device.EndScene();
device.Present();
this.Invalidate();
}
private void SetUpCamera()
{
device.Transform.Projection = Matrix.PerspectiveFovLH((float)Math.PI / 4, (float)this.Width / (float)this.Height, 0.3f, 500f);
device.Transform.View = Matrix.LookAtLH(new Vector3(0, -1f, 0.2f), new Vector3(0, 0, 0), new Vector3(0, 0, 1));
}
private void LoadTexturesAndMaterials()
{
material = new Material();
material.Diffuse = Color.White;
material.Ambient = Color.White;
device.Material = material;
scenerytexture = TextureLoader.FromFile(device, "texturemap.jpg");
}
private void LoadFloorplan()
{
WIDTH = 20;
HEIGHT = 15;
int_Floorplan = new int[,]
{
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1},
{1,0,0,0,0,0,0,0,0,0,0,0,0,0,1},
{1,0,0,1,1,0,0,0,1,1,0,0,1,0,1},
{1,0,0,1,1,0,0,0,1,0,0,0,1,0,1},
{1,0,0,0,1,1,0,1,1,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,0,0,1,0,0,1},
{1,0,0,0,0,0,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,0,0,0,0,0,1},
{1,0,1,1,0,0,0,1,0,0,0,0,0,0,1},
{1,0,1,0,0,0,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,1,0,0,0,1,0,0,0,0,1},
{1,0,1,0,0,0,0,0,0,1,0,0,0,0,1},
{1,0,1,1,0,0,0,0,1,1,0,0,0,1,1},
{1,0,0,0,0,0,0,0,1,1,0,0,0,1,1},
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1},
};
Random random = new Random();
for (int x = 0; x < WIDTH; x++)
{
for (int y = 0; y < HEIGHT; y++)
{
if (int_Floorplan[x, y] == 1)
{
int_Floorplan[x, y] = random.Next(differentbuildings) + 1;
}
}
}
}
private void LoadMesh(string filename, ref Mesh mesh, ref Material[] meshmaterials, ref Texture[] meshtextures, ref float meshradius)
{
ExtendedMaterial[] materialarray;
mesh = Mesh.FromFile(filename, MeshFlags.Managed, device, out materialarray);
if ((materialarray != null) && (materialarray.Length > 0))
{
meshmaterials = new Material[materialarray.Length];
meshtextures = new Texture[materialarray.Length];
for (int i = 0; i < materialarray.Length; i++)
{
meshmaterials[i] = materialarray[i].Material3D;
meshmaterials[i].Ambient = meshmaterials[i].Diffuse;
if ((materialarray[i].TextureFilename != null) && (materialarray[i].TextureFilename != string.Empty))
{
meshtextures[i] = TextureLoader.FromFile(device, materialarray[i].TextureFilename);
}
}
}
mesh = mesh.Clone(mesh.Options.Value, CustomVertex.PositionNormalTextured.Format, device);
mesh.ComputeNormals();
VertexBuffer vertices = mesh.VertexBuffer;
GraphicsStream stream = vertices.Lock(0, 0, LockFlags.None);
Vector3 meshcenter;
meshradius = Geometry.ComputeBoundingSphere(stream, mesh.NumberVertices, mesh.VertexFormat, out meshcenter) * scaling;
}
private void LoadMeshes()
{
LoadMesh("xwing.x", ref spacemesh, ref spacemeshmaterials, ref spacemeshtextures, ref spacemeshradius);
}
private void DrawMesh(Mesh mesh, Material[] meshmaterials, Texture[] meshtextures)
{
for (int i = 0; i < meshmaterials.Length; i++)
{
device.Material = meshmaterials[i];
device.SetTexture(0, meshtextures[i]);
mesh.DrawSubset(i);
}
}
private void UpdatePosition(ref Vector3 position, Vector3 angles, float speed)
{
Vector3 addvector = new Vector3();
addvector.X += (float)(Math.Sin(angles.Z));
addvector.Y += (float)(Math.Cos(angles.Z));
addvector.Z -= (float)(Math.Tan(angles.Y));
addvector.Normalize();
position += addvector * speed;
}
private void InitializeInputDevices()
{
keyb = new DI.Device(SystemGuid.Keyboard);
keyb.SetCooperativeLevel(this, CooperativeLevelFlags.Background | CooperativeLevelFlags.NonExclusive);
keyb.Acquire();
}
private void ReadUserInput(float speed)
{
KeyboardState keys = keyb.GetCurrentKeyboardState();
if (keys[Key.Right])
{
spacemeshangles.X += 2.5f * speed;
}
if (keys[Key.Left])
{
spacemeshangles.X -= 2.5f * speed;
}
if (keys[Key.Down])
{
spacemeshangles.Z -= (float)(speed * Math.Sin(spacemeshangles.X));
spacemeshangles.Y -= (float)(speed * Math.Cos(spacemeshangles.X));
}
if (keys[Key.Up])
{
spacemeshangles.Z += (float)(speed * Math.Sin(spacemeshangles.X));
spacemeshangles.Y += (float)(speed * Math.Cos(spacemeshangles.X));
}
}
private int CheckCollision(Vector3 position, float radius)
{
if (position.Z - radius < 0) return 1;
if (position.Z + radius > 15) return 2;
if ((position.X < -10) || (position.X > WIDTH+10)) return 2;
if ((position.Y < -10) || (position.Y > HEIGHT+10)) return 2;
if ((position.X - radius > 0) && (position.X + radius < WIDTH) && (position.Y - radius> 0) && (position.Y + radius < HEIGHT))
{
if (position.Z - radius < buildingheights[int_Floorplan[(int)position.X, (int)position.Y]]) return 1;
}
return 0;
}
private void VertexDeclaration()
{
float imagesintexture = 1 + differentbuildings * 2;
for (int x = 0; x < WIDTH; x++)
{
for (int y = 0; y < HEIGHT; y++)
{
int currentbuilding = int_Floorplan[x, y];
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y, buildingheights[currentbuilding]), new Vector3(0, 0, 1), (currentbuilding * 2 + 1) / imagesintexture, 1));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x + 1, y, buildingheights[currentbuilding]), new Vector3(0, 0, 1), currentbuilding * 2 / imagesintexture, 1));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x + 1, y + 1, buildingheights[currentbuilding]), new Vector3(0, 0, 1), currentbuilding * 2 / imagesintexture, 0));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x + 1, y + 1, buildingheights[currentbuilding]), new Vector3(0, 0, 1), currentbuilding * 2 / imagesintexture, 0));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y + 1, buildingheights[currentbuilding]), new Vector3(0, 0, 1), (currentbuilding * 2 + 1) / imagesintexture, 0));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y, buildingheights[currentbuilding]), new Vector3(0, 0, 1), (currentbuilding * 2 + 1) / imagesintexture, 1));
if (y > 0)
{
if (int_Floorplan[x, y - 1] != int_Floorplan[x, y])
{
if (int_Floorplan[x, y - 1] > 0)
{
currentbuilding = int_Floorplan[x, y - 1];
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y, 0f), new Vector3(0, 1, 0), (currentbuilding * 2 - 1) / imagesintexture, 1));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x + 1, y, buildingheights[currentbuilding]), new Vector3(0, 1, 0), currentbuilding * 2 / imagesintexture, 0));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x + 1, y, 0f), new Vector3(0, 1, 0), currentbuilding * 2 / imagesintexture, 1));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x + 1, y, buildingheights[currentbuilding]), new Vector3(0, 1, 0), currentbuilding * 2 / imagesintexture, 0));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y, 0f), new Vector3(0, 1, 0), (currentbuilding * 2 - 1) / imagesintexture, 1));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y, buildingheights[currentbuilding]), new Vector3(0, 1, 0), (currentbuilding * 2 - 1) / imagesintexture, 0));
}
if (int_Floorplan[x, y] > 0)
{
currentbuilding = int_Floorplan[x, y];
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y, 0f), new Vector3(0, -1, 0), currentbuilding * 2 / imagesintexture, 1));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x + 1, y, 0f), new Vector3(0, -1, 0), (currentbuilding * 2 - 1) / imagesintexture, 1));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x + 1, y, buildingheights[currentbuilding]), new Vector3(0, -1, 0), (currentbuilding * 2 - 1) / imagesintexture, 0));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y, 0f), new Vector3(0, -1, 0), currentbuilding * 2 / imagesintexture, 1));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x + 1, y, buildingheights[currentbuilding]), new Vector3(0, -1, 0), (currentbuilding * 2 - 1) / imagesintexture, 0));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y, buildingheights[currentbuilding]), new Vector3(0, -1, 0), currentbuilding * 2 / imagesintexture, 0));
}
}
}
if (x > 0)
{
if (int_Floorplan[x - 1, y] != int_Floorplan[x, y])
{
if (int_Floorplan[x - 1, y] > 0)
{
currentbuilding = int_Floorplan[x - 1, y];
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y, 0f), new Vector3(1, 0, 0), currentbuilding * 2 / imagesintexture, 1));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y + 1, 0f), new Vector3(1, 0, 0), (currentbuilding * 2 - 1) / imagesintexture, 1));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y + 1, buildingheights[currentbuilding]), new Vector3(1, 0, 0), (currentbuilding * 2 - 1) / imagesintexture, 0));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y + 1, buildingheights[currentbuilding]), new Vector3(1, 0, 0), (currentbuilding * 2 - 1) / imagesintexture, 0));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y, buildingheights[currentbuilding]), new Vector3(1, 0, 0), currentbuilding * 2 / imagesintexture, 0));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y, 0f), new Vector3(1, 0, 0), currentbuilding * 2 / imagesintexture, 1));
}
if (int_Floorplan[x, y] > 0)
{
currentbuilding = int_Floorplan[x, y];
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y, 0f), new Vector3(-1, 0, 0), (currentbuilding * 2 - 1) / imagesintexture, 1));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y, buildingheights[currentbuilding]), new Vector3(-1, 0, 0), (currentbuilding * 2 - 1) / imagesintexture, 0));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y + 1, 0f), new Vector3(-1, 0, 0), currentbuilding * 2 / imagesintexture, 1));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y, buildingheights[currentbuilding]), new Vector3(-1, 0, 0), (currentbuilding * 2 - 1) / imagesintexture, 0));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y + 1, buildingheights[currentbuilding]), new Vector3(-1, 0, 0), currentbuilding * 2 / imagesintexture, 0));
verticeslist.Add(new CustomVertex.PositionNormalTextured(new Vector3(x, y + 1, 0f), new Vector3(-1, 0, 0), currentbuilding * 2 / imagesintexture, 1));
}
}
}
}
}
verticesarray = (CustomVertex.PositionNormalTextured[])verticeslist.ToArray(typeof(CustomVertex.PositionNormalTextured));
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose(disposing);
}
private void InitializeComponent()
{
this.components = new System.ComponentModel.Container();
this.Size = new System.Drawing.Size(500, 500);
this.Text = "Riemer's DirectX Tutorial using C# -- Season 2";
}
static void Main()
{
using (WinForm our_directx_form = new WinForm())
{
our_directx_form.InitializeDevice();
our_directx_form.SetUpCamera();
our_directx_form.LoadFloorplan();
our_directx_form.VertexDeclaration();
our_directx_form.LoadTexturesAndMaterials();
our_directx_form.LoadMeshes();
our_directx_form.InitializeInputDevices();
Application.Run(our_directx_form);
}
}
}
}
- Website design & XNA + DirectX code : Riemer Grootjans -
©2003 - 2008 Riemer Grootjans
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