Bringing it all together

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Bringing it all together

• Bryan Duggan
• Hugh McAtamney

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Summary

• We can now use
• Vectors
• To represent position and orientation
• Represent a camera
• Vector arithmetic
• To move things
• Matrices
• To translate
• To rotate
• To scale
• To program the rendering pipeline
• DirectX
• To create a surface for drawing
• To create and draw textured vertex buffers

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Whats left

• Meshes
• Game entities
• Collision detection
• Then we can build a complete world to play with
• The world Textured polygons, vertex buffers
• The player The camera
• Daleks/projectiles - Mesh
• Ammunition - Mesh

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Mesh

• A mesh is a
• File
• Memory representation (vertex buffer etc)
• Loader
• It holds
• Vertices
• Indexes
• Normals
• Textures
• Materials
• Animation
• We can create a mesh in a 3D Editor

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3D Editors

• Milkshape
• 3D Studio Max
• Maya
• GMax

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X Files

• In Direct X, meshes are stored with a .x
  extension
• Can be binary or text format
• We can use a 3D editor to export to the .x file
  format
• There is a .x file viewer with the DirectX SDK

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xof 0303txt 0032 // DirectX - from
MilkShape3D Frame dalekFrame
FrameTransformMatrix
1.000000,0.000000,0.000000,0.000000,
0.000000,1.000000,0.000000,0.000000,
0.000000,0.000000,1.000000,0.000000,
0.000000,0.000000,0.000000,1.000000
Mesh dalekMesh 15872
0.0774927.0544702.468911,
0.1152847.0469692.468383,
0.1152847.0208392.466543,
0.0674677.0303272.467211,
0.0875177.0786102.470611,
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Other formats

• FarCry
• Quake
• Half Life 1/2
• 3DS
• Etc.

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Mesh concepts

• Subsets
• Meshes are divided into subsets parts of the
  mesh with different materials textures
• Materials
• Determine how the light interacts with the subset

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Mesh API Calls

• To create a mesh from a file
• ID3DXBuffer adjBuffer 0
• ID3DXBuffer mtrlBuffer 0
• DWORD numMtrls 0
• hr D3DXLoadMeshFromX(
• _meshName.c_str(),
• D3DXMESH_MANAGED,
• device,
• adjBuffer,
• mtrlBuffer,
• 0,
• numMtrls,
• _mesh)

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Mesh API Calls

• mtrlBuffer points to a buffer for materials (used
  for lighting) and texture file names
• We then have to iterate through this buffer and
  load any required textures

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In code

• for(int i 0 i lt numMtrls i)
• // the MatD3D property doesn't have an ambient
  value set
• // when its loaded, so set it now
• mtrlsi.MatD3D.Ambient mtrlsi.MatD3D.Diffuse
  
• // save the ith material
• _materials.push_back( mtrlsi.MatD3D )
• // check if the ith material has an associative
  texture
• if( mtrlsi.pTextureFilename ! 0 )
• // yes, load the texture for the ith subset
• IDirect3DTexture9 tex 0
• D3DXCreateTextureFromFile(
• device,
• mtrlsi.pTextureFilename,
• tex)

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Optimise the mesh

• hr _mesh-gtOptimizeInplace(
• D3DXMESHOPT_ATTRSORT
• D3DXMESHOPT_COMPACT
• D3DXMESHOPT_VERTEXCACHE,
• (DWORD)adjBuffer-gtGetBufferPointer(),
• 0, 0, 0)

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Drawing the mesh

• We iterate through the subsets and draw each one
  with the appropriate material and texture
• for(int i 0 i lt _materials.size() i)
• Device-gtSetMaterial( _materialsi )
• Device-gtSetTexture(0, 0)
• Device-gtSetTexture(0, _texturesi)
• _mesh-gtDrawSubset(i)

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Other useful Mesh API calls

• D3DXCreateBox
• D3DXCreateSphere
• D3DXCreateCylinder
• D3DXCreateTeapot
• D3DXCreatePolygon
• D3DXCreateTorus

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Bounding volumes

• D3DXComputeBoundingBox
• D3DXComputeBoundingSphere
• Do these return coordinates in local space or
  world space?

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In code

• BYTE v 0
• _mesh-gtLockVertexBuffer(0, (void)v)
• D3DXComputeBoundingBox(
• (D3DXVECTOR3)v,
• _mesh-gtGetNumVertices(),
• D3DXGetFVFVertexSize(_mesh-gtGetFVF()),
• _min,
• _max)
• _mesh-gtUnlockVertexBuffer()

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In code

• void MeshWrappercomputeBoundingSphere()
• // Now compute the bounding rectangle
• BYTE v 0
• _mesh-gtLockVertexBuffer(0, (void)v)
• D3DXComputeBoundingSphere(
• (D3DXVECTOR3)v,
• _mesh-gtGetNumVertices(),
• D3DXGetFVFVertexSize(_mesh-gtGetFVF()),
• _center,
• _radius)
• _mesh-gtUnlockVertexBuffer()

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As we are good OO games programmers

• We add a MeshWrapper class to the framework
• Extends DrawableEntity
• Encapsulate all this messy and repetitive code
• Simply call setMeshName, before calling setup
• This leads us onto

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OO

• Computer games programmers need to be good OO
  thinkers
• Games are complicated
• Games need to be fast
• Most games naturally fit the OO paradigm
  (European OO)
• Problems in games (such as asset management etc.
  etc. etc.) can be solved using design patterns
  (USA OO)
• Games APIs (DirectX/OpenGL) are written in C/C
• Games are written in C
• Complex C code can be visualised in UML

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Games are written in C

• Almost universally!!
• Why
• Access to native code (DirectX/OpenGL)
• OO
• Speed
• Portability?

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Games engines

• Written in C
• Are supported by embedded scripting languages,
  such as Lua
• Flexibility
• Ability to create MODs
• Ability to expose C objects/APIs

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Dalek World design

• Based on the functionality of the Dalek World
  game what should our design be?
• Existing classes
• Direct3dBase
• DrawableEntity
• BoundableEntity
• MeshWrapper
• Wall
• World
• DalekWorld
• What else do we need?

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New classes

• MoveableEntity
• Has position, orientation (look)
• Can move (walk, strafe)
• Can look (yaw, roll, pitch)
• Has speed
• Camera
• As above
• But can also generate a view matrix
• Projectile
• As MoveableEntity
• Has a mesh, so it can draw itself
• But can be fired and hit things
• GameEntity
• As MoveableEntity
• But also has a MeshWrapper, so it can draw itself

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New classes

• Ammo
• As above
• But also rotates, respawns, can be picked up
• AutonomousGameEntity
• As GameEntity
• But can make decisions and move autonomously, (to
  come later)
• Dalek
• As above
• But also can fire projectiles
• Can also pick up ammo
• Has health and ammo stats

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UML Class diagram