CS314 Project 4
Carmen (Jia Min) Liang, Eason (Yu Shun) Hu

SNOWBALL GAME
Advanced Functionality:
*	Particle system
	o	Exploding bubbles
*	Procedural modeling (Bonus feature)
	o	Sphere cloud at game over stage
*	Collision Detection
	o	Penguin boundary collision detection
	o	Snowballs hitting penguins
	o	Disappearing of snowballs
*	Animation
	o	Swinging penguins
	o	Spinning penguins
	o	Penguins flying off while been shot
	o	Rolling snowballs

Algorithms:
*	Collision detection: use radius to detect collision
	o	Snowball collision with Penguins
*	Find the center of snowball and the center of Penguin
*	Calculate the distance in between
*	If the distance is small than the sum of the radius of snowball and the radius of Penguin
*	Penguins flying off
	o	Snowball boundary collision
*	Snowballs will disappear while out of the icy floor
	o	Penguin boundary collision
*	Penguins cannot go out of icy floor; they will get new direction 
*	Penguin**s new direction is calculated like light reflection (similar to light reflection)

*	Picking:
	o	Use the mouse to determine the coordinates
	o	Go in to Render-Select mode
	o	Pick matrix()
	o	Set up the camera
	o	Assign ID and draw objects
	o	Get number of hits
	o	Analysis number hits and select-buffer
	o	Find the smallest depth value for the meaningful ID

*	Camera movements:
	o	Rotate clock wise or counter clockwise with respect to the game floor center
	o	Roll and translate around the game floor along the center**s x-axis

*	Texturing:
	o	Load image to GPU
	o	Initialize the textures
	o	Map the texture on the object

*	On screen control panel:
	o	Go into ortho graphic matrix
	o	Raster position and print text
	o	Get out or ortho graphic matrix

*	Particle system:
	o	Generate a big collection of half-transparent balloons with different color (particles)
	o	Balloons are going out in all directions with different speed, different color

*	Gameplay: 
	o	Idea: Throw snowballs to kill the penguins
	o	To Win: kill all penguins within the time limit
	o	The maximum number of available snowballs is 4
	o	If one snowball is gone, one donut on floor increases
	o	Right click to get a donut can increases the number of available snowballs by 1

Data structures:
	o	Snowball
	o	Penguin
	o	Floor items
	o	Particle
	o	Particle collection

Game instructions:
*	Keyboard keys
	o	"a" : move the camera clockwise around the center**s y-axis
	o	"d" : move the camera counter-clockwise around the center**s y-axis
	o	"w" : rolling around center**s x-axis in counter-clockwise
	o	"s" : rolling around center**s x-axis in clockwise
*	Mouse
	o	**left click**: shooting snowballs
	o	**right click**: picking up donuts to increase number of snowballs available

Sources:
http://www.gamedev.net/community/forums/topic.asp*topic_id=82893
http://www.opengl.org/sdk/docs/man/xhtml/glSelectBuffer.xml
http://nehe.gamedev.net/data/lessons/lesson.asp*lesson=32
http://nehe.gamedev.net/data/articles/article.asp*article=06
http://www.opengl.org/sdk/docs/man/xhtml/glSelectBuffer.xml
http://www.opengl.org/resources/faq/technical/selection.htm#sele0020
http://jerome.jouvie.free.fr/OpenGl/Lessons/Lesson5.php