Objects Reference

class bezier_patch : public base_object

Definition

class bezier_patch : public base_object
{
public:
    int mode;   // 2 for quadratic and 3 for cubic
    vector *p; // the surface control points
    vector *t; // the surface texture control points
    int np,     // num points
        npu,    // num points in u dir
        npv,    // num points in v dir
        nsu,    // num segments in u dir
        nsv;    // num segments in u dir

    int levelu,levelv; // subdivision level in u and v
    int nvertu,nvertv; // surface num vertices in u and v
    int texpic,lm;      // texture and lightmap
    vector *surf;       // discretized surface
    vector pivot;       // the pivot position

  void reset();
  int load_pch(char *file);
  void build_loft(bezier_curve *shape,bezier_curve *path,int texture,int lightmap,float tileu,float tilev);
  void evaluate(int evaltype,float u,float v,vector *dest);
  void build_surface();
  void illuminate(vector& p,float rad,vector& color,int shadows);
  void draw(int nleveldrop=0);
  mesh *build_mesh();

  bezier_patch() { p=0; t=0; surf=0; reset(); };
  ~bezier_patch() { reset(); };
};

Data Members

Member	Type	Description
mode	int	Bezier patch mode: 3 for quadratic 4 for cubic
pivot	vector	pivot position
p	vector *	the patch control points array
t	vector *	the patch coltrol points tetxure coordinates array (x,y) for texture map co-ordinates (z,w) for lightmap texture co-ordinates
np	int	number of points in control points array
npu	int	number of points in u dir
npv	int	number of points in v dir
nsu	int	number of segments in u dir
nsv	int	number of segments in v dir
levelu	int	subdivision level in u
levelv	int	subdivision level in v
nvertu	int	number of discretized vertices in u dir nvertu = (1<<levelu)+1
nvertv	int	number of discretized vertices in v dir nvertv = (1<<levelv)+1
texpic	int	texture applyed to the patch (-1 for none)
lm	int	light_map applyed to the patch (-1 for none)
surf	vector *	discretized surface points 2 vectors per entry (point and tetxure co-ordinates) size = 2sizeof(vector)nvertu*nvertv

Methods

reset, build_loft, evaluate, build_surface, build_mesh, illuminate, draw, load_pch

Remarks

This class implements a Bezier patch. The patch can have any number of segments in u and v directions. The patch is made of several connected cubic or quadratic Bezier patches (nsu is the numbre of patches in the u dir and nsv in the v dir).

For quadratic patches:
nsu = (spu-2)/2
nsv = (spv-2)/2

For cubic patches:
nsu = (spu-1)/2
nsv = (spv-1)/2

The surface is discretized based on the subdivision level. The number of vertices in u and v dir are:

nvertu = (1<<levelu)*nsu+1
nvertv = (1<<levelv)*nsv+1

At run-time, the surface car be draw at any level of detail up to its current selected level. The draw function includes a parameter that represents the number of levels of detail to drop on draw. The numbrer of vertices skipped (col/row draw loop increment) on each direction is: