Patent ID: 8169435

Claim:
A method of operating a processing apparatus to render on a display device a model of a surface of paper or foil wrinkly material usable for packaging, the method comprising: accepting a garment, being a description of the different parts of the surface of paper or foil wrinkly material, and how and where any of the parts are connected; discretizing the garment to form a triangular mesh comprising triangles; modeling the physics of the triangular mesh, and running a simulation to find a stable end-state for the triangular mesh, including defining an energy function and modifying the triangular mesh to achieve a lower energy value; modifying the triangular mesh to visually smooth the mesh in a way that is perceived as typical for paper or foil flexible packaging material; and rendering the model on a display device, wherein the modifying the triangular mesh to visually smooth the mesh includes modifying the triangular mesh during the rendering or modifying the triangular mesh prior to the rendering, wherein the rendering includes shading mesh triangles, wherein the shading of a mesh triangle uses normals that vary across the mesh triangle with limited secondary curvature in a manner characteristic of paper or foil wrinkly material, and wherein the shading includes approximately meeting each of four normal conditions including: along the edges of the mesh triangles, except for the vertices of the mesh triangles, the normal remains constant; the inside of each mesh triangle is shaded with a continuous normal that is also continuous with the normal at the edges of the mesh to give the inside of the mesh triangle a smooth appearance; the vertices of each mesh triangle are singular points; and in the direct vicinity of the singular points, the normal changes along the axial direction and the normal is constant along the radial direction.