Extended Features

In addition, upon further investigation, Eileen Hebets recognized the use of this spider was not limited to the male species in her research. Another area that had never been explored before included studying the courtship displays between a virtual female spider with a live male spider specimen. That is, reversing the roles between the gender that is displayed on video versus the gender of the live specimen under study could now be easily achieved. Thus, another extension made in this project includes animation of a female spider. Since the user can easily modify the geometry through the Matlab GUI, differences in morphological traits between the genders did not need further enhancements.

See Usage section to download the spider simulation with extended features.

• 1 Animation
• 2 Matlab GUI
• 2.1 View Submenus
• 2.2 Spline Graphs
• 3 MEX-files Interface
• 4 OpenGL
• 5 Demos

1 Animation

In order to support the extended features above, the animation now includes movement in the front two leg pairs depending on the gender and side selected by the user. If the male is chosen, the user is allowed control over the 2 front forelegs (i.e., leg pair I). If a female spider is chosen, the user must also choose between the left and right side. This will enable movement of 2 legs as well. However, female courtship displays include synchronized movement of the 2 legs (one leg each in leg pair I and II.) In addition, the synchronized movement must consist of 2 legs on the same side. See Demos section for examples illustrating the differences between the genders.

2 Matlab GUI

The user interface has been extended with the following features:

2.1 View Submenus

The View Menu options have changed to include a submenu for the gender and one for the species.

2.2 Spline Graph

The south panel of the Spider GUI has been modified as well. Radio buttons were added here to allow for the user to select between the left and right side. The spline graph displayed will correspond to the data points for the side that is chosen. That is, the spline graph displayed now depends not only on which leg joint is chosen, but also on which leg the user selected. This will allow for manipulation on all 8 leg joints (4 joints for the right leg, and 4 joints for the left leg).

3 MEX-files

Since there are now essentially 8 joints to track time steps for in the animation, the amount of data that will need to be passed from the matlab GUI to the OpenGL will essentially double. Specifically, the vars array data structure in Matlab will contain 482 more data points than before, for a total of 1115 data points. Since both legs can move, an additional 480 interpolated data points are needed to track the angle at which each joint is positioned on each time step for the right leg (4 leg joints * 120 data points for each joint). In addition, 2 additional data points are needed to track the gender and the side that is selected by the user.

4 OpenGL

The rendering in OpenGL has pretty much remained the same as before. Changes here primarily deal with the additional data points involved in calculating the position of the 2nd leg. If the user selected a male spider, the side does not matter since both legs can potentially move. Movement in the right leg can be differentiated with movement in the left by the data points that are passed in through the MEX-Array.

5 Demos

The following .avi files demonstrate the differences in courtship display behaviors of each gender.

• Simulation of a female spider during courtship
• Simulation of a male spider during courtship

The image on the left is of a male spider. Notice both front forelegs are captured in mid motion. This can be contrasted to the image on the right of a female spider, where leg pairs I and II are affected, but movement occurs on only one side of the spider.