XNA L08–Amazing XNA Utilities

Mohammad Shakermohammadshaker.com

@ZGTRShaker2011, 2012, 2013, 2014

XNA Game DevelopmentL08 – Amazing XNA Utilities

Collision Detection

Collision Detectiondetermines whether two objects overlap and therefore have

collided in your virtual world.

Collision DetectionAccurate collision detection is fundamental

to a solid game engine.

Your cars would drive off the road, your people would walk through buildings, and your camera

would travel through cement walls :D

Collision Detection

• Microsoft Book, Chapter 18, Page: 285

Collision Detection

• XNA has two main types for implementing collision detection

Collision Detection


– BoundingBox

Collision Detection


– BoundingBox

– BoundingSphere

Collision Detection


– BoundingBox

• a box will better suit a rectangular high-rise building

– BoundingSphere

Collision Detection


– BoundingBox

• a box will better suit a rectangular high-rise building

– BoundingSphere

• a bounding sphere offers a better fit for rounded objects such as a domed arena

Collision Detection

– BoundingSphere

Collision Detection

– BoundingSphere

Collision Detection

– BoundingSphere

Collision Detection

– BoundingSphere

Collision Detection

• CONTAINMENT TYPE

– BoundingBox

– BoundingSphere

Collision Detection


– BoundingBox

– BoundingSphere

Collision Detection


– BoundingBox

– BoundingSphere

Collision DetectionBOUNDING BOX

Collision Detection - BOUNDING BOX

• Initializing the Bounding BOX

• Intersects() common overloads

BoundingBox boundingBox = new BoundingBox(Vector3 min, Vector3 max);

public bool Intersects(BoundingBox box);

public bool Intersects(BoundingSphere sphere);

Collision Detection - BOUNDING BOX

• Comparing one bounding box with another:

• Comparing a bounding box with a bounding sphere:

• Comparing a bounding box with a single three-dimensional position:

public void Contains(ref BoundingBox box, out ContainmentType result);

public void Contains(ref BoundingSphere sphere, out ContainmentType result);

public void Contains(ref Vector3 point, out ContainmentType result);

Collision DetectionBOUNDING SPHERE

Collision Detection - BOUNDING SPHERE

• Initializing the Bounding Sphere

• Intersects() Common Overloads

• Contains()

public BoundingSphere(Vector3 center, float radius);



public void Contains(ref BoundingSphere sphere,out ContainmentType result);



Collision Detection - BOUNDING SPHERE

• Initializing the Bounding Sphere

• Intersects() Common Overloads

• Contains()



public void Contains(ref BoundingSphere sphere,out ContainmentType result);



a three-dimensional position

public BoundingSphere(Vector3 center, float radius);

Collision Detection

• Different sphere groups for varying levels of efficiency and accuracy

Collision Detection

• Microsoft, Collision Detection, P: 290 - 304

Check it out in “App1-CollisionDetection-

Micosoft”

Collision DetectionApress book, Chapter 13, Page 367

Collision Detection

Collision Detection

• Also, because the default model processor doesn’t generate a bounding box

(AABB) volume, we need to generate one for the model

Collision Detection

• Avoid testing the collision with each mesh of the model, by creating a global

bounding sphere (or global bounding Box) for the entire model!

Collision Detection

• Usage of bounding spheres is emphasized because spheres are easier to update

and transform than bounding boxes

EARLY WARNING SYSTEMSDon’t check a 200 miles sphere collision with you!

Rbwhitaker web site: http://rbwhitaker.wikidot.com/collision-detection

http://rbwhitaker.wikidot.com/collision-detection

Collision Detection

• Approximation

Collision Detection

• Approximation

Collision Detection

• Approximation

Collision Detection

• Approximation

When to use What?

Collision Detection

• Approximation

A better way to combine both approaches

Collision Detectionhierarchical modeling

Collision Detection

Collision Detection

Collision Detection

Collision DetectionIn hierarchical model you would use both the

large sphere, and the small spheres.

Collision DetectionQuad Tree Approach

Collision Detection Example in XNA

private bool IsCollision(Model model1, Matrix world1, Model model2, Matrix world2)

{

for (int meshIndex1 = 0; meshIndex1 < model1.Meshes.Count; meshIndex1++)

{

BoundingSphere sphere1 = model1.Meshes[meshIndex1].BoundingSphere;

sphere1 = sphere1.Transform(world1);

for (int meshIndex2 = 0; meshIndex2 < model2.Meshes.Count; meshIndex2++)

{

BoundingSphere sphere2 = model2.Meshes[meshIndex2].BoundingSphere;

sphere2 = sphere2.Transform(world2);

if (sphere1.Intersects(sphere2))

return true;

}

}

return false;

}

Collision Detection Example in XNA

“App2-CollisionDetection-WebSite”

XNA With Windows Form App/ WPF AppFor more info, go to:

http://www.codeproject.com/KB/game/XNA_And_Beyond.aspx

XNA With Windows Form App

• 2 WAYS!

– 2D Graphics (Professional)

– Windows Forms (Ordinary)


• 2 WAYS!


• See the appendix for full tutorial pdf



• 2 WAYS!




• Use the appended project directly


• 2 WAYS!




• Use the appended project directly

• OR, do it your self as the following slides


• Windows Forms! (See the template project in appendix)


• Steps

– Add new Form in the same XNA Project (“Form1”);

– Add Panel to the form you have just created (“Form1”);

– Add to the top of “Form1”

public IntPtr PanelHandle

{

get

{

return this.panel1.IsHandleCreated? this.panel1.Handle : IntPtr.Zero;

}

}


• Now, In Game1 class do the following

– Add the following at the top (using, renaming namespace)

– Create a reference to Form1 to handle the instance at runtime;using SysWinForms = System.Windows.Forms;

Form1 myForm;



– Add the following two methods

– Create a reference to Form1 to handle the instance at runtime;

– Initialize

void myForm_HandleDestroyed(object sender, EventArgs e)

{

this.Exit();

}

void gameWindowForm_Shown(object sender, EventArgs e)

{

((SysWinForms.Form)sender).Hide();

}



– Add the following code to Initialize() method

– Create a reference to Form1 to handle the instance at runtime;

– Initialize

protected override void Initialize()

{

SysWinForms.Form gameWindowForm =

(SysWinForms.Form)SysWinForms.Form.FromHandle(this.Window.Handle);

gameWindowForm.Shown += new EventHandler(gameWindowForm_Shown);

this.myForm = new Form1();

myForm.HandleDestroyed += new EventHandler(myForm_HandleDestroyed);

myForm.Show();

base.Initialize();

}



– Add the following code to Draw() method so it looks like this

protected override void Draw(GameTime gameTime)

{

GraphicsDevice.Clear(Color.CornflowerBlue);

base.Draw(gameTime);

// This one will do the trick we are looking for!

this.GraphicsDevice.Present(null, null, myForm.PanelHandle);

}


• Now, ctrl+F5 and u r good to go!

2D and 3D Combined

2D and 3D Combined

2D and 3D Combined

2D and 3D Combined

2D and 3D Combined

2D and 3D Combined

2D and 3D Combined

Begin Method (SpriteSortMode, BlendState, SamplerState,

DepthStencilState,

RasterizerState,

Effect,

Matrix)

Begin Method ()

Begin Method (SpriteSortMode, BlendState)


DepthStencilState,

RasterizerState)


DepthStencilState,

RasterizerState,

Effect)

sortModeSprite drawing order.

blendStateBlending options.

samplerStateTexture sampling options.

depthStencilStateDepth and stencil options.

rasterizerStateRasterization options.

effectEffect state options.

transformMatrixTransformation matrix for scale, rotate,

translate options.

2D and 3D Combined

• SpriteSortMode

2D and 3D Combined

• BlendState

• See more: http://msdn.microsoft.com/en-us/library/microsoft.xna.framework.graphics.blend.aspx

2D and 3D Combined

• BlendState

2D and 3D Combined

• BlendState

2D and 3D Combined

• BlendState

2D and 3D Combined

spriteBatch.Begin();

spriteBatch.Begin(SpriteSortMode.Immediate,

BlendState.Opaque);

• finally! change SpriteBatch From

• To

2D and 3D Combined



BlendState.Opaque);


• To

2D and 3D Combined



BlendState.AlphaBlend);


• To

2D and 3D Combined


spriteBatch.Begin(SpriteSortMode.BackToFront,

BlendState.AlphaBlend);


• To

Viewports & Split Screen Games


• Base Project

• “App1-Viewports”


• Viewports


• Viewports – Multiple ones

So, What’s the idea is all about?!



Multiple “Camera”s



Multiple “LookAt()”s


• Global Scope

private Matrix topView = Matrix.CreateLookAt(new Vector3(0, 0, 4),

new Vector3(0, 0, 0), new Vector3(0, 0.001f, 1f));

private Matrix frontView = Matrix.CreateLookAt(new Vector3(0, 4, 0),

new Vector3(0, 0, 0), Vector3.UnitZ);

private Matrix sideView = Matrix.CreateLookAt(new Vector3(4, 0, 0),


private Matrix perspectiveView = Matrix.CreateLookAt(new Vector3(4, 4, 4),


private Viewport topViewport;

private Viewport sideViewport;

private Viewport frontViewport;

private Viewport perspectiveViewport;

private Matrix topView = Matrix.CreateLookAt(new Vector3(0, 0, 4),

new Vector3(0, 0, 0), new Vector3(0, 0.001f, 1f));

private Matrix frontView = Matrix.CreateLookAt(new Vector3(0, 4, 0),


private Matrix sideView = Matrix.CreateLookAt(new Vector3(4, 0, 0),


private Matrix perspectiveView = Matrix.CreateLookAt(new Vector3(4, 4, 4),


private Viewport topViewport;

private Viewport sideViewport;

private Viewport frontViewport;

private Viewport perspectiveViewport;

Matrix.CreateLookAt(CameraPosition, CameraTarget, CameraUp);


LookAt()

• Initialize()protected override void Initialize()

{

base.Initialize();

int ViewportWidth = 200;

int ViewportHeight = 200;

Viewport defaultViewport = GraphicsDevice.Viewport;

topViewport = defaultViewport;

topViewport.X = 0;

topViewport.Y = 0;

topViewport.Width = ViewportWidth;

topViewport.Height = ViewportHeight;

topViewport.MinDepth = 0;

topViewport.MaxDepth = 1;

sideViewport = defaultViewport;

sideViewport.X = ViewportWidth;

sideViewport.Y = 0;

sideViewport.Width = ViewportWidth;

sideViewport.Height = ViewportHeight;

sideViewport.MinDepth = 0;

sideViewport.MaxDepth = 1;

frontViewport = defaultViewport;

frontViewport.X = 0;

frontViewport.Y = ViewportHeight;

frontViewport.Width = ViewportWidth;

frontViewport.Height = ViewportHeight;

frontViewport.MinDepth = 0;

frontViewport.MaxDepth = 1;

perspectiveViewport = defaultViewport;

perspectiveViewport.X = ViewportWidth;

perspectiveViewport.Y = ViewportHeight;

perspectiveViewport.Width = ViewportWidth;

perspectiveViewport.Height =

ViewportHeight;

perspectiveViewport.MinDepth = 0;

perspectiveViewport.MaxDepth = 1;

}




{

base.Initialize();





topViewport.X = 0;

topViewport.Y = 0;







sideViewport.Y = 0;

















ViewportHeight;



}


{

base.Initialize();





topViewport.X = 0;

topViewport.Y = 0;







sideViewport.Y = 0;

















ViewportHeight;



}



{

base.Initialize();





topViewport.X = 0;

topViewport.Y = 0;







sideViewport.Y = 0;

















ViewportHeight;



}









• Draw()protected override void Draw(GameTime gameTime)

{ GraphicsDevice.Clear(Color.CornflowerBlue);

Viewport original = graphics.GraphicsDevice.Viewport;

graphics.GraphicsDevice.Viewport = topViewport;

//GraphicsDevice.Clear(Color.Black);

DrawModel(model, world, topView, projection);

graphics.GraphicsDevice.Viewport = sideViewport;


DrawModel(model, world, sideView, projection);

graphics.GraphicsDevice.Viewport = frontViewport;


DrawModel(model, world, frontView, projection);

graphics.GraphicsDevice.Viewport = perspectiveViewport;


DrawModel(model, world, perspectiveView, projection);

GraphicsDevice.Viewport = original;


}



















}



















}



















}



















}


• “App2-ViewportsFinished”

Picking Objects

Picking Objects

• How to pick?!

Picking Objects

• How to pick?!

Picking Objects

public Ray CalculateRay(Vector2 mouseLocation, Matrix view, Matrix projection,

Viewport viewport)

{

Vector3 nearPoint = viewport.Unproject(

new Vector3(mouseLocation.X, mouseLocation.Y, 0.0f),

projection,

view,

Matrix.Identity);

Vector3 farPoint = viewport.Unproject(

new Vector3(mouseLocation.X, mouseLocation.Y, 1.0f),

projection,

view,

Matrix.Identity);

Vector3 direction = farPoint - nearPoint;

direction.Normalize();

return new Ray(nearPoint, direction);

}

Picking Objects

public bool Intersects(Vector2 mouseLocation,

Model model, Matrix world, Matrix view, Matrix projection,

Viewport viewport)

{

for (int index = 0; index < model.Meshes.Count; index++)

{

BoundingSphere sphere = model.Meshes[index].BoundingSphere;

sphere = sphere.Transform(world);

float? distance = IntersectDistance(sphere, mouseLocation, view, projection, viewport);

if (distance != null)

{

return true;

}

}

return false;

}

Picking Objects

public float? IntersectDistance(BoundingSphere sphere, Vector2 mouseLocation,

Matrix view, Matrix projection, Viewport viewport)

{

Ray mouseRay = CalculateRay(mouseLocation, view, projection, viewport);

return mouseRay.Intersects(sphere);

}

Picking Objects

• “App-Picking”

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Technology

XNA L08–Amazing XNA Utilities