To Store the 3D model parsed from a wrl file.
modelCoord[]: This is an array of type vert3D. It is used to store the vertices of the 3D model. Each element in the array is a vertex.
modelCon[] : This is an array of type integer. It is used to store the edges of the 3D model. Each element in the array stores the two end vertices of an edge.
viewCoord[]: This is an array of type vert3D. It is used to store the coordinate of each vertex after transformed.
nvert: This is an integer recording how many vertices are in the model.
ncon: This is an interger recording how many edges are in the model.