Project Documentation

Documentation for JModeler

Author (chronologically): (biswarup, chiragp, devesh, dharm, vikasj)@cse.iitb.ac.in

Creating a Curve/Surface

In this document, the term object refers to a curve or a surface. In order to create an object, click on the File Menu, and select an appropriate option. A dialogue box would open up, through which you can choose name and color for the object. Also, you will have to input a file consisting of control points for the object being created. Format of these files is described in the following subsection. Lastly, you would have to choose the segment length(s) for the object being created.

Format of the control points files

For a curve

x₁ y₁ z₁ x₂ y₂ z₂ ... x_n y_n z_n , where x_i is the x co-ordinate of the i^th control point.

For a surface

x[0][0] y[0][0] z[0][0] ... x[0][m] y[0][m] z[0][m]
.
.
x[n][0] y[n][0] z[n][0] ... x[n][m] y[n][m] z[n][m]
where m is degree of the surface in parameter u and n is the degree in parameter v.

Options associated with an object

There are two panels shown in the jModeler window. The left pannel (L), lists all the object names, while the right one (R) displays/hides the objects. In the left pannel, selecting a object with left-mouse-click and then right-clicking on it, displays the following options :

Show : to display the object in R .
Hide : to hide the object.
Rename : to rename the object.
Delete : to delete the object.
Curvature : to get the curvature of the object at a given point, specified by the t-value for a curve and by u,v values for a surface.
Toggle control points : Makes the control points visible/invisible depending upon whether they were invisible/visible earlier (basically toggle between visible/invisible objects).
Isoparametric lines : For a surface, this plots a given number of isoparametric lines. One will have to specify the parameter (u or v) with respect to which the iso-parametric curves will be drawn.
Toggle fill triangles: For a surface, the constituent triangles are displayed/hidden explicity depending upon whether they were hidden/displayed earlier (also a toggle button).
Tangent : Displays a tangent line/plane for a given curve/surface at a given point.

Buttons:

Zoom :

Buttons for Zoom in and Zoom out, let you zoom in/out with the zoom settings as specified by Settings button. Settings for maximum/minimum zoom range and zoom-step can be specified with the help of this button.

Rotate :

It is possilbe to rotate the displayed objects, by pressing the left-mouse button and dragging it on R . To understand how actually this rotation works,one could check how the co-ordinate axes move with a rotation. For this, the button Show/Hide Axis can be used, which toggles the display of co-ordinate axis.

Mouse Sensitivity :

In the Settings button, an option for the navigation speed is specified with the Mouse Sensitivity parameter. Increasing the value of that variable will increase the speed with which the object rotates/translates on mouse movements.