-int drawbox(double xmin, double ymin, double xmax, double ymax);
-/* gp.c */
-int gptrace(int state);
-int viewprt3(double xmin, double ymin, double zmin, double xmax, double ymax, double zmax);
-int window3(double xmin, double ymin, double xmax, double ymax);
-int setproj(int pr, double x, double y, double z);
-int setvrp(double x, double y, double z);
-int setvpn(double x, double y, double z);
-int setvup(double x, double y, double z);
-int viewdepth(double front, double back);
-int gpfrontclip(int on_off);
-int gpbackclip(int on_off);
-int calcnper(void);
-int calcnpar(void);
-int calcrot(double rot[5][5]);
-int calcpertrans(void);
-int calcpartrans(void);
-int matident(double mtx[5][5]);
-int matmult(double premtx[5][5], double postmtx[5][5], double result[5][5]);
-int crossprod(struct point *v, struct point *w, struct point *result);
-int transform(double mtx[5][5], double *x, double *y, double *z);
-int homotrans(double mtx[5][5], double *x, double *y, double *z, double *w);
-int moveabs3(double x, double y, double z);
-int moverel3(double xr, double yr, double zr);
-int lineabs3(double x, double y, double z);
-int linerel3(double xr, double yr, double zr);
-int drawline(double xinput, double yinput, double zinput);
-int mastertondc(double *x, double *y, double *z);
-int checkchange(void);
-int initgrf3(void);
-int termgrf3(void);
-int matwrite(double mtx[5][5]);
-int pyr_edge(double x, double y, double z, int *pos);
-int clippyramid(double *x1, double *y1, double *z1, double *x2, double *y2, double *z2, int *accept);
-int cube_edge(double x, double y, double z, int *pos);
-int clipcube(double *x1, double *y1, double *z1, double *x2, double *y2, double *z2, int *accept);
-/* pickbox.c */
-int pickbox(int dev, int *xmin, int *ymin, int *xmax, int *ymax, int xtab[], int ytab[]);
-/* pickloc.c */
-int pickloc(int dev, int *xloc, int *yloc, int xtab[], int ytab[]);
-/* pixblock.c */
-int readblock(char array[], int x1, int y1, int x2, int y2);
-int writeblock(char array[], int x1, int y1, int mode);
-char *allocblock(int x1, int y1, int x2, int y2);
-/* readloc.c */
-int readloc(int dev, int *x, int *y);
-int loc_to_ndc(int xloc, int yloc, float *xndc, float *yndc);
-int readbutt(int dev);