OpenGL Game

1
OpenGL Game

• by
• Neal Patel

2
Motivation

• Learn the basics of game programming
• Experience for future development in a growing
  industry
• Fun

3
Introduction

• Computer Games once used to be considered
  children toys.
• Now they have grown into a multi-billion dollar
  market.
• Games have come to be known as one of the more
  creative forms of software development.
• Game developers are drawn into this industry by
  the idea of creating their own virtual world that
  people will one day experience.

4
Elements of A Game

• Graphics
• Input
• Music and Sound
• Game Logic and Artificial Intelligence
• Networking
• User Interface and Menuing System

5
Simplistic Game Architecture
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More Advanced Game Architectural Design
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Enough Small Talk

• API used for system
• OpenGL
• Open Graphics Library interface to graphics
  hardware.
• SDL
• Simple DirectMedia Layer cross platform
  multimedia library designed to provide fast
  access to the graphics framebuffer and audio
  device.
• Milkshape 3D 3D animation modeler

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SDL Architecture
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Concepts Learned from Programming

• Texture mapping
• Loads BMP file via SDL LoadBMP routine
• SDL_Surface imageSDL_LoadBMP(bitmap.bmp)
• If(image!NULL)
• SDL_BlitSurface(image, NULL, screen, NULL)
• SDL_UpdateRect(screen,0,0,0,0)
• This should create memory space for an image,
  load it from a file, and display it onto the
  screen
• Blit - To copy a large array of bits from one
  part of a computer's memory to another part.

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Special Effects Presented

• Particle Systems
• Through clever use of textures and other
  properties particle systems can be used to create
  effects like fire, smoke explosions, liquid
  (water or blood) spraying, snow, star fields,
  etc..
• Attributes the particle system possess.
• Position
• Velocity
• Life Span
• Color

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Particle Effect (cont.)

• effect ParticleEffect(
• EXPLOSION, //Type of particle effect
• NONE, //Type of collision detection
• Vector(0.0f, 0.0f, 0.6f), //Gravity vector
  50, //How random to spray things out
• 0, //How long the effect will last
• 0, //How long in frames before each particle
  begins to fade Vector( 5.5f, 5.5f, 0.5f ),
  //The origin of the effect
• Color( r, g, b ), //The color of the
  effect
• "Data/Texture/Particle.bmp //What texture
  to load
• )

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Other special effects

• Billboarding
• Allows a polygon to always face the viewer. As
  the player moves at an angle, they will be able
  to see the object at an angle.
• Collision Detection
• Bounding square technique surrounds a object in
  the world along their extreme points.
• A collision is registered whenever the distance
  between the player and the enemy is less than the
  sum of the enemy radius and the player radius.

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Gameplay

• Enemies die when they collide with the player,
  dealing damage to the player equal to (250/e),
  where e is the initial number of enemies on the
  map.
• The initial health of the player is 100 and
  initial number of enemies is set to 50.
  Therefore each collision with the enemy will
  cause the player to lose 5 health. Health of the
  enemy is set to 0.

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User Interface
Control Actions
W or UP arrow Move forwards
S or BACK arrow Move backwards
A Strafe Left
D Strafe Right
Mouse Left or LEFT arrow Look Left
Mouse Right or RIGHT arrow Look Right
Mouse UP Look Up
Mouse Down Look Down
Enter or space Fire (to be implemented)
Escape Key Kill Application
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SDL implementation for control keys

• if(keysSDLK_UP keysSDLK_w)
• dx (float)(PLAYER_SPEEDcos(aPI180))
• dy (float)(PLAYER_SPEEDsin(aPI180))
• if(keysSDLK_DOWN keysSDLK_s)
• dx - (float)(PLAYER_SPEEDcos(aPI180))
• dy - (float)(PLAYER_SPEEDsin(aPI180))
• if(keysSDLK_d)
• dx (float)(PLAYER_SPEED0.5fsin(aPI180))
• dy - (float)(PLAYER_SPEED0.5fcos(aPI180))
• if(keysSDLK_a)
• dx - (float)(PLAYER_SPEED0.5fsin(aPI180))
• dy (float)(PLAYER_SPEED0.5fcos(aPI180))

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How the world was generated

• First, the map is filled with empty tiles, and
  the border tiles are made solid. A random point
  is then selected, and either a horizontal or
  vertical line of walls is drawn across the room,
  leaving a open space to navigate to different
  rooms. This process is called recursively until
  rooms are of an acceptable size.

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Drawing and loading texture to a wall

• glColor3f(1,1,1)
• glBindTexture(GL_TEXTURE_2D, walltex)
• glBegin(GL_QUADS)
• if(type(i1,j)0)
• glNormal3i(1,0,0)
• glTexCoord2d(0,0)
• glVertex3i(i1, j, 0)
• glTexCoord2d(1,0)
• glVertex3i(i1, j1, 0)
• glTexCoord2d(1,1)
• glVertex3i(i1, j1, 1.5f)
• glTexCoord2d(0,1)
• glVertex3i(i1, j, 1.5f)

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Future Work

• Implement so player can fire a weapon like a real
  first person shooter is supposed to do.
• Add item pickups such as multiple weapons and
  ammo
• Better enemies with more advanced AI
• And why not networking

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Conclusion

• Today game software is developed in teams, where
  each member works on his or her specialty until
  the work is integrated to create a work single
  coherent work of art. They take years to
  develop. Working with my abilities this is the
  end result. Hope you enjoyed.

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References

• Hawkins, Kevin and Dave Astle. OpenGL Game
  Programming. Premier Press, May 2004.
• Woo, Mason, J. Neider, and T. Davis. OpenGL
  Programming Guide. Addison-Wesley, fourth
  edition, November 2003.
• www.opengl.org
• www.libsdl.org
• www.gamedev.net
• www.gametutorials.com
• http//nehe.gamedev.net/
• http//www.psionic3d.co.uk/