Vector fields may be defined on planar grids or curved surfaces. They are always associated with a point set, e.g. the vertices of a surface, such each surface vertex is the base point of a single vector of the vector field. Different visualization methods allow to display vector fields as a collection of arrows, as integral curves, or as LIC images (Line Integral Convolution).
The centers/singularities of the vector field are the vertices of a point set. Keep pressing key 'a' while pressing the left mouse button to add a center with the properties that you can select on the right part below. Keep pressing 'p' and continuously drag a single center to change it's position.
View source code:
PaVectorField.java of applet,
PjVectorField.java of project,
PjVectorField_IP.java of project panel.