A Logo-style turtle is inherited for the graphical interpretation of L-Systems. The turtle can be controlled by modules which have a specific command associated with it. The characteristics of the turtle can be initialized through parameters in the view file (see Appendix II) and can be modified throughout productions by various modules (see Appendix I). The following parameters form the characteristics of the turtle (see Figure 2.1)[1]:

• position in a three-dimensional coordinate system.
• heading vector specifying the orientation of the turtle.
• left vector.
• up vector.
• line width specifying the current width of a line or cylinder that is being drawn by the turtle.
• color index specifying the current color or material.
• texture index specifying the current texture.
• contour specifying the current contour for generalized cylinders.
• elasticities specifying the susceptibility of the direction adjustments due to tropisms by a set of parameters.

Figure 2.1 Turtle Parameters

					Preface Parameters Appendix I Appendix II References
Index	Circles and Spheres	Generalized Cylinders	Surfaces	Textures