a lamp contains color and intensity values; and a camera object contains intrinsic viewing parameters.

The Mesh data structure is used by the blender

Blender rendered. This component is developed independently since heretical and graphical rendering must be performed simultaneously and synchronously. A simulation loop is used to update hepatic rendering forces at a rate which maintains stability and quality.

Where the force feedback vector which is displayed to the user is computed using the stiffness coefficient (variable name stiffness) for the object and x the |penetration depth (displacement) of the hepatic proxy into an object. The stiffness coefficient has a range of [0,1],where 0 represents no resistance to deformation and 1 represents the maximum stiffness which may be rendered by the hepatic device. The damping of an object defines its resistance to the rate of deformation due to some applied strut Hepatices force. It is typically rendered using the force equation:

Hepatic Properties

In this section we'll briefly discuss the hepatic properties which may currently be modeled using HAMLAT. It is important for the modeler to understand these properties and their basis for use in hepatic rendering.

The stiffness of an object defines how resistant it is to deformation by some applied force. Hard objects, such as a rock or table, have very high stiffness; soft objects, such as rubber ball, have low stiffness. The hardness-softness of an object is typically rendered using the spring-force equation: range of [0,1] and may be used to model viscous behavior of a material. It also increases the stability of the hepatic rendering loop ford stiff materials.

The static friction (variable name striation) and dynamic friction (variable name direction) coefficient are used to model the frictional forces experienced while exploring the surface of a 3D object. Static friction is experienced when the proxy is not moving over the object's surface, and an initial force must be used to overcome static friction. Dynamic friction is felt when the proxy moves across the surface, rubbing against it. Frictional coefficients also have a range of /0,1], with a value of 0 making the surface of a 3D object feel "slippery" and a value of 1 making the object feel very rough.

B. Editing

Blender uses a set of non-overlapping windows called spaces to modify various aspects of the 3D scene and its objects. Each space is divided into a set of areas and panels which are context aware. That is, they provide functionality based on the selected object type. For example, if a camera is selected the panel will display components which allow the modeler to change the focal length and viewing angle of the camera, but these components will not appear if an object of another type is selected.

Figure 6 shows a screen shot of the button space which is used to edit properties for a hepatic mesh. It includes user-interface panels which allow a modeler to change the graphical shading properties of the mesh, perform simple re-meshing operations, and to modify the hepatic properties of the selected mesh.