Project Title

• Title: Bees
• Author: Ian Chase
• Date: March 2, 1998

Introduction

I will model how bees swarm out of their hive. The particle system should model the bees initially swarming out of the hive and then flying around the hive looking for someone to sting. This particle system may eventually be incorporated in my "Man Runs From Bees" animation. This animation contains a scene in which a man will run past the hive, bumping it slightly causing all the bees to come out. Some will chase the man, while other bees will remain, circling around the hive.

Particle Systems Model

• Model Type Description

  The model will consist of two main types of objects: The hive and the bees. For this animation the hive will not change in any way. All of the motion will be the bees that come out of the hive. The bees will emerge from the bottom of the hive, at first they will fly downward to distance themselves from the hive and then they will begin their swarming motion around the hive. The constraint on the bee particles will be that they cannot exceed a predetermined distance from the hive. No external forces will act on the bees other than an internal instinct to stay near the hive.

• List of Properties that are Determined at Birth
  1. Lifetime: These bees are immortal. They never die and they never get tired. They live from the time they are born to the time the program terminates.
  2. Max. number of children: The bees will not spawn any children
     (only the queen bee can do that and she remains in the hive)
  3. Generation number: There will be no need to keep track of the generation number.
  4. Material and basic shape properties will be determined at birth. + Each bee will be two SoSphere with one SoCone
  5. Speed scale value: this is a value that will be used in the fuctions which determine the position of the bee

• List of Properties that are Initialized at Birth and May Change During Lifetime
  1. Geometry
     • The geometry of each bee will remain constant during lifetime.
  2. Material
     • The body of the bee will be black for the most part, except for the sphere which makes the midsection of the bee. This sphere will initially be red signifying that the bee is angry. As time progresses this color will change to yellow.
  3. Motion
     • Positional motion will vary in in every axis (x,y,z) according to a fuction composed of a trig function and random number generator. The function will also figure in the the speed scale value of the bee, so each bee can move at a different speed.
     • Rotational motion will only vary along the x and y axis. The function for determining the bee's rotational values will be similar to the function which determines the positional values.

• List and Description of Evolution Rules
  1. Properties Determined at Birth
     1. Each of the spheres and the cone of the bee will have a mean radius of 1 with a variance of 0.5.
     2. Each of the bees will have a speed scale value of 5 with a vairance of .75.
  2. Properties that May Change During Lifetime
     1. The speed scale value of each bee will continuous decrease over its lifetime at a rate of .001 for each second until the speed scale value reaches a constant value of 1.
     2. The x,y,z positions fo the bees will be determined by a hermite function. At first all of the bees will descend downward and then they will begin their swarming motion which will consist of a randomly shaped eliptical path around the hive.

Data Structure Definition

class Bee
{
  public:
    Bee();	// Create a bee with a 'random' initial velocity
    void Update();	// Calculate the new values for the x,y,z
			// position and adjust speed scale value
  protected:
    SoSphere* beeBody;
    SoSphere* beeHead;
    SoTransformation* HeadTrans;
    SoCone* beeTail;
    SoTransformation* TailTrans;
    SoScale* beeSize;
    float speed;	// For calculating the next 
			// position with deceleration
}; // class Bee

class BeeNode
{
  public:
    BeeListNode();
    void SetNextNode(BeeNode* next);
  protected:
    Bee beeData;
    BeeNode* nextNode;
}; // class BeeNode

class BeeList
{
  public:
    BeeList();
    Bool Add(BeeNode* node);
    int GetCount();
  protected:
    int beeCount;
    BeeNode* head, *tail;
}; // class BeeList

Simulation Program Description

• Initialize system state
• main simulation loop: for frame = 0, numFrames-1
  • simulation time = frame # / frame rate (i.e., rate in frames/sec.)
  • loop: for each particle
    • apply rules for updating motion
    • apply rules for updating position
    • apply rules for updating orientation (rotation on x and y)

Rendering Program Description

There will not be anything particularly special about how the particles are rendered. Each particle is made from simple Inventor nodes and do not require any special processing.