1. Mohammad Shaker
mohammadshaker.com
@ZGTRShaker
2011, 2012, 2013, 2014
XNA Game Development
L08 – Amazing XNA Utilities

2. Collision Detection

3. Collision Detection
determines whether two objects overlap and therefore have
collided in your virtual world.

4. Collision Detection
Accurate collision detection is fundamental
to a solid game engine.

6. Your cars would drive off the road, your people
would walk through buildings, and your camera
would travel through cement walls :D

8. Collision Detection
• Microsoft Book, Chapter 18, Page: 285

9. Collision Detection
• XNA has two main types for implementing collision detection

10. Collision Detection
• XNA has two main types for implementing collision detection
– BoundingBox

11. Collision Detection
• XNA has two main types for implementing collision detection
– BoundingBox
– BoundingSphere

12. Collision Detection
• XNA has two main types for implementing collision detection
– BoundingBox
• a box will better suit a rectangular high-rise building
– BoundingSphere

13. Collision Detection
• XNA has two main types for implementing 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

14. Collision Detection
– BoundingSphere

15. Collision Detection
– BoundingSphere

16. Collision Detection
– BoundingSphere

17. Collision Detection
– BoundingSphere

18. Collision Detection
• CONTAINMENT TYPE
– BoundingBox
– BoundingSphere

19. Collision Detection
• CONTAINMENT TYPE
– BoundingBox
– BoundingSphere

20. Collision Detection
• CONTAINMENT TYPE
– BoundingBox
– BoundingSphere

21. Collision Detection
BOUNDING BOX

22. 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);

23. 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);

24. Collision Detection
BOUNDING SPHERE

25. Collision Detection - BOUNDING SPHERE
• Initializing the Bounding Sphere
• Intersects() Common Overloads
• Contains()
public BoundingSphere(Vector3 center, float radius);
public bool Intersects(BoundingBox box);
public bool Intersects(BoundingSphere sphere);
public void Contains(ref BoundingSphere sphere,out ContainmentType result);
public void Contains(ref BoundingBox box, out ContainmentType result);
public void Contains(ref Vector3 point, out ContainmentType result);

26. Collision Detection - BOUNDING SPHERE
• Initializing the Bounding Sphere
• Intersects() Common Overloads
• Contains()
public bool Intersects(BoundingBox box);
public bool Intersects(BoundingSphere sphere);
public void Contains(ref BoundingSphere sphere,out ContainmentType result);
public void Contains(ref BoundingBox box, out ContainmentType result);
public void Contains(ref Vector3 point, out ContainmentType result);
a three-dimensional position
public BoundingSphere(Vector3 center, float radius);

27. Collision Detection
• Different sphere groups for varying levels of efficiency and accuracy

28. Collision Detection
• Microsoft, Collision Detection, P: 290 - 304

29. Check it out in
“App1-CollisionDetection-
Micosoft”

30. Collision Detection
Apress book, Chapter 13, Page 367

31. Collision Detection

32. Collision Detection
• Also, because the default model processor doesn’t generate a bounding box
(AABB) volume, we need to generate one for the model

33. 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!

34. Collision Detection
• Usage of bounding spheres is emphasized because spheres are easier to update
and transform than bounding boxes

35. EARLY WARNING SYSTEMS
Don’t check a 200 miles sphere collision with you!
Rbwhitaker web site: http://rbwhitaker.wikidot.com/collision-detection

36. Collision Detection
• Approximation

37. Collision Detection
• Approximation

38. Collision Detection
• Approximation

39. Collision Detection
• Approximation
When to use What?

40. Collision Detection
• Approximation
A better way to combine
both approaches

41. Collision Detection
hierarchical modeling

42. Collision Detection

43. Collision Detection

44. Collision Detection

45. Collision Detection
In hierarchical model you would use both the
large sphere, and the small spheres.

46. Collision Detection
Quad Tree Approach

47. 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;
}

48. Collision Detection Example in XNA
“App2-CollisionDetection-WebSite”

49. XNA With Windows Form App/ WPF App
For more info, go to:
http://www.codeproject.com/KB/game/XNA_And_Beyond.aspx

50. XNA With Windows Form App
• 2 WAYS!
– 2D Graphics (Professional)
– Windows Forms (Ordinary)

51. XNA With Windows Form App
• 2 WAYS!
– 2D Graphics (Professional)
• See the appendix for full tutorial pdf
– Windows Forms (Ordinary)

52. XNA With Windows Form App
• 2 WAYS!
– 2D Graphics (Professional)
• See the appendix for full tutorial pdf
– Windows Forms (Ordinary)
• Use the appended project directly

53. XNA With Windows Form App
• 2 WAYS!
– 2D Graphics (Professional)
• See the appendix for full tutorial pdf
– Windows Forms (Ordinary)
• Use the appended project directly
• OR, do it your self as the following slides

54. XNA With Windows Form App
• Windows Forms! (See the template project in appendix)

55. XNA With Windows Form App
• 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;
}
}

56. XNA With Windows Form App
• 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;

57. XNA With Windows Form App
• Now, In Game1 class do the following
– 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();
}

58. XNA With Windows Form App
• Now, In Game1 class do the following
– 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();
}

59. XNA With Windows Form App
• Now, In Game1 class do the following
– 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);
}

60. XNA With Windows Form App
• Now, ctrl+F5 and u r good to go!

61. 2D and 3D Combined

62. 2D and 3D Combined

63. 2D and 3D Combined

64. 2D and 3D Combined

65. 2D and 3D Combined

66. 2D and 3D Combined

67. 2D and 3D Combined
Begin Method (SpriteSortMode, BlendState, SamplerState,
DepthStencilState,
RasterizerState,
Effect,
Matrix)
Begin Method ()
Begin Method (SpriteSortMode, BlendState)
Begin Method (SpriteSortMode, BlendState, SamplerState,
DepthStencilState,
RasterizerState)
Begin Method (SpriteSortMode, BlendState, SamplerState,
DepthStencilState,
RasterizerState,
Effect)
sortMode
Sprite drawing order.
blendState
Blending options.
samplerState
Texture sampling options.
depthStencilState
Depth and stencil options.
rasterizerState
Rasterization options.
effect
Effect state options.
transformMatrix
Transformation matrix for scale, rotate,
translate options.

68. 2D and 3D Combined
• SpriteSortMode

69. 2D and 3D Combined
• BlendState
• See more: http://msdn.microsoft.com/en-us/library/microsoft.xna.framework.graphics.blend.aspx

70. 2D and 3D Combined
• BlendState

71. 2D and 3D Combined
• BlendState

72. 2D and 3D Combined
• BlendState

73. 2D and 3D Combined
spriteBatch.Begin();
spriteBatch.Begin(SpriteSortMode.Immediate,
BlendState.Opaque);
• finally! change SpriteBatch From
• To

74. 2D and 3D Combined
spriteBatch.Begin();
spriteBatch.Begin(SpriteSortMode.Immediate,
BlendState.Opaque);
• finally! change SpriteBatch From
• To

75. 2D and 3D Combined
spriteBatch.Begin();
spriteBatch.Begin(SpriteSortMode.Immediate,
BlendState.AlphaBlend);
• finally! change SpriteBatch From
• To

76. 2D and 3D Combined
spriteBatch.Begin();
spriteBatch.Begin(SpriteSortMode.BackToFront,
BlendState.AlphaBlend);
• finally! change SpriteBatch From
• To

77. Viewports & Split Screen Games

78. Viewports & Split Screen Games
• Base Project
• “App1-Viewports”

79. Viewports & Split Screen Games
• Viewports

80. Viewports & Split Screen Games
• Viewports – Multiple ones
So, What’s the idea
is all about?!

81. Viewports & Split Screen Games
• Viewports – Multiple ones
Multiple “Camera”s

82. Viewports & Split Screen Games
• Viewports – Multiple ones
Multiple “LookAt()”s

83. Viewports & Split Screen Games
• 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),
new Vector3(0, 0, 0), Vector3.UnitZ);
private Matrix perspectiveView = Matrix.CreateLookAt(new Vector3(4, 4, 4),
new Vector3(0, 0, 0), Vector3.UnitZ);
private Viewport topViewport;
private Viewport sideViewport;
private Viewport frontViewport;
private Viewport perspectiveViewport;

84. 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),
new Vector3(0, 0, 0), Vector3.UnitZ);
private Matrix perspectiveView = Matrix.CreateLookAt(new Vector3(4, 4, 4),
new Vector3(0, 0, 0), Vector3.UnitZ);
private Viewport topViewport;
private Viewport sideViewport;
private Viewport frontViewport;
private Viewport perspectiveViewport;
Matrix.CreateLookAt(CameraPosition, CameraTarget, CameraUp);
Viewports & Split Screen Games

85. LookAt()

86. • 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;
}
Viewports & Split Screen Games

87. Viewports & Split Screen Games
• 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;
}

88. • 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;
}
Viewports & Split Screen Games

89. • 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;
}
Viewports & Split Screen Games

90. Viewports & Split Screen Games

91. Viewports & Split Screen Games

92. Viewports & Split Screen Games

93. Viewports & Split Screen Games

94. Viewports & Split Screen Games

95. Viewports & Split Screen Games

96. Viewports & Split Screen Games
• 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;
//GraphicsDevice.Clear(Color.Black);
DrawModel(model, world, sideView, projection);
graphics.GraphicsDevice.Viewport = frontViewport;
//GraphicsDevice.Clear(Color.Black);
DrawModel(model, world, frontView, projection);
graphics.GraphicsDevice.Viewport = perspectiveViewport;
//GraphicsDevice.Clear(Color.Black);
DrawModel(model, world, perspectiveView, projection);
GraphicsDevice.Viewport = original;
base.Draw(gameTime);
}

97. Viewports & Split Screen Games
• 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;
//GraphicsDevice.Clear(Color.Black);
DrawModel(model, world, sideView, projection);
graphics.GraphicsDevice.Viewport = frontViewport;
//GraphicsDevice.Clear(Color.Black);
DrawModel(model, world, frontView, projection);
graphics.GraphicsDevice.Viewport = perspectiveViewport;
//GraphicsDevice.Clear(Color.Black);
DrawModel(model, world, perspectiveView, projection);
GraphicsDevice.Viewport = original;
base.Draw(gameTime);
}

98. Viewports & Split Screen Games
• 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;
//GraphicsDevice.Clear(Color.Black);
DrawModel(model, world, sideView, projection);
graphics.GraphicsDevice.Viewport = frontViewport;
//GraphicsDevice.Clear(Color.Black);
DrawModel(model, world, frontView, projection);
graphics.GraphicsDevice.Viewport = perspectiveViewport;
//GraphicsDevice.Clear(Color.Black);
DrawModel(model, world, perspectiveView, projection);
GraphicsDevice.Viewport = original;
base.Draw(gameTime);
}

99. Viewports & Split Screen Games
• 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;
//GraphicsDevice.Clear(Color.Black);
DrawModel(model, world, sideView, projection);
graphics.GraphicsDevice.Viewport = frontViewport;
//GraphicsDevice.Clear(Color.Black);
DrawModel(model, world, frontView, projection);
graphics.GraphicsDevice.Viewport = perspectiveViewport;
//GraphicsDevice.Clear(Color.Black);
DrawModel(model, world, perspectiveView, projection);
GraphicsDevice.Viewport = original;
base.Draw(gameTime);
}

100. Viewports & Split Screen Games
• 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;
//GraphicsDevice.Clear(Color.Black);
DrawModel(model, world, sideView, projection);
graphics.GraphicsDevice.Viewport = frontViewport;
//GraphicsDevice.Clear(Color.Black);
DrawModel(model, world, frontView, projection);
graphics.GraphicsDevice.Viewport = perspectiveViewport;
//GraphicsDevice.Clear(Color.Black);
DrawModel(model, world, perspectiveView, projection);
GraphicsDevice.Viewport = original;
base.Draw(gameTime);
}

101. Viewports & Split Screen Games
• “App2-ViewportsFinished”

102. Picking Objects

103. Picking Objects
• How to pick?!

104. Picking Objects
• How to pick?!

105. 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);
}

106. 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;
}

107. 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);
}

108. Picking Objects
• “App-Picking”

109. Take a Look on my other courses
@ http://www.slideshare.net/ZGTRZGTR
Available courses to the date of this slide:

110. http://www.mohammadshaker.com
mohammadshakergtr@gmail.com
https://twitter.com/ZGTRShaker @ZGTRShaker
https://de.linkedin.com/pub/mohammad-shaker/30/122/128/
http://www.slideshare.net/ZGTRZGTR
https://www.goodreads.com/user/show/11193121-mohammad-shaker
https://plus.google.com/u/0/+MohammadShaker/
https://www.youtube.com/channel/UCvJUfadMoEaZNWdagdMyCRA
http://mohammadshakergtr.wordpress.com/