STISIM Drive
(SDL) - TREE - Roadside Trees
Display trees along the
sides of the roadway. This event will allow you to specify the number of trees,
tree density and tree type. You use this event to turn the displaying of trees
on and off for particular sections of your simulation. This allows you to
transition from a rural setting into a town by initially having the trees on
and then turning them off as the driver approaches the town. If you do not use
the TREE event, then no trees will be displayed on the sides of the roadway.
Although you now have some control over how trees are displayed in the roadway
scene, you still do not have total control. For most of the TREE event
parameters, you will be specifying a range of values that the parameters can be
within, and the simulation will randomly choose the actual values that will be
used for each tree. Of course, the values that the program chooses will be
within the limits specified. See the section on random numbers for some
additional insight into using random numbers and how it may affect the
displaying of trees.
EVENT PARAMETERS:
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PARAMETER 1: |
Maximum number of trees that will be displayed at any one time. Since it takes a finite amount of time to display the trees, you will need to decide the maximum amount of trees that your scenario can handle without degrading the simulation performance. In general, a maximum of 50-100 trees gives good results. Setting this parameter to 0 will prevent trees from being displayed until a new TREE event is processed. The maximum number of trees allowed is 250, and the distribution of the trees is affected by the clipping plane distance set in the configuration option. The program tries to distribute the number of trees over the clipping plane distance, therefore the shorter the clipping plane distance is the tighter the trees will appear. |
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PARAMETER 2: |
Density that will be used to determine when a new tree will be added. A minimum value of 10 is required. Higher values of density will spread the trees out, lower values will guarantee that the maximum number of trees are displayed, but they may all be grouped together. This will result in clumps of trees instead of a random dispersion of trees. For good dispersion, a value of 50 produces a nice result. |
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PARAMETER 3: |
Type of tree that will be
displayed. There are currently 2 types of trees that the simulation will display.
To choose the tree type set parameter 3 to one of the following: 0 - Randomly choose from
the number of trees available |
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PARAMETER 4: |
Minimum lateral distance from the roadway centerline to the trees, in feet. |
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PARAMETER 5: |
Maximum lateral distance from the roadway centerline to the tree, in feet. |
EXAMPLE:
1000,TREE,15,50,0,20,200
In the example shown, trees
will begin to appear after the driver has driven 1000 feet, and will appear in
front of the driver at a distance that is equal to or greater than the far
clipping plane parameter specified in the simulators configuration. A maximum
of 15 trees will be displayed and they have a density factor of 15. These
parameters will allow for a random display of trees that are not closely
grouped, therefore there should be a steady progression of trees as the driver
traverses the roadway. Since parameter 3 is set to 0, both types of trees will
be displayed. Finally, the trees will appear anywhere from 20 to 200 feet away
from the roadway centerline.