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The diagram from the previous page also illustrates three possible outcomes to the particles once they are created:
(1) The particle wonders randomly until it is found to be adjacent to a sticked particle or ground. In this case, the particle sticks and becomes part of the growing plant.
(2) The particle wanders too far away from the plants and is subsequently destroyed when it reaches the limit boundary.
(3) If a particle is found to move across the 'garden edge' or the graphic screen edge, it will reappear on the opposite side of the screen. This is called warp around.
Note that both (1) and (2) outcomes result in creation of a new moving particle.
The Fractal Applet also includes some extra features in addition to the original diffusion limited aggragation model. On the right hand side of the applet screen are three scroll bars labelled as Gravity, Flow and
Stickiness respectively. Changing these controls will influence the plant growth. Basically, Gravity and Flow change the way a moving particle wanders. These values will have a range between 0 to 1.00 inclusive with an increment of 0.01 unit.
Stickiness, on the other hand defines the probability for a moving particle to stick once it is found to be adjacent to the ground or sticked particles. It has a range between 0.01 to 1.00 inclusive. You cannot have a stickiness value of zero. This means particle never stick
and no plants can ever be grown!
(1) Gravity: This changes the probability for a moving particle to move downward. The downward probability is defined as:
Downward probabity = 0.25 + (0.25 x Gravity)
So when the Gravity is set at the default value of 0.00, downward probability = 0.25. When Gravity is set to the maximum of 1.00, downward probabiliy = 0.50.
(2) Flow: This is similar to the Gravity. However, instead of moving downward Flow changes the probability of a moving particle to move rightwards. The rightward probability is defined as:
Rightward probabity = 0.25 + (0.25 x Flow)
Similar to the Gravity, the default value for the Flow is 0.00. When Flow is set to the maximum of 1.00 this means the particle has 50% (0.50) chances to move right. Note that when both Gravity and Flow are set to the maximum values a particle can only move either down or right.
(3) Stickiness: The default value is set to 1.00. This means that the moment a moving particle is found to be adjacent to other sticked particle or ground it will stick. However, any other values means the particle carries certain probability whether it will stick or not. If the particle does not stick it will 'bounce' back to its previous position and the motion continues.
Note that once a particle has sticked it will never dislodge itself.
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