//  three.h


//  Contour plots

typedef void *(*startcontourpp)(real V);
typedef void *(*neighbourcpp)(void *L, void *R);
typedef void (*posncontourpp)(void *N, vector *V);
typedef bool (*donecontourpp)(void *L, void *R);
typedef void *(*nextcontourpp)(void *N);

typedef struct {
window         *wind;     //  the window being drawn to
projection     *proj;     //  perspective in which the contours are to be drawn
startcontourpp start;     //  call-back for entry node to left of contour
neighbourcpp   neigh;     //  call-back for common neighbour to two given nodes
posncontourpp  where;     //  call-back for real (x,y,value) coordinates of node
donecontourpp  done;      //  call-back for whether contour has reached the far boundary
void           *outline;  //  starting node for outline
nextcontourpp  loop;      //  call-back for next node c.c.w. along boundary
colour         rgb;       //  the colour
bool           ticks;     //  whether tick marks are to be drawn
real           level,     //  value of current contour
               tickfrac;  //  how far along a contour the tick mark is drawn
int            max;       //  maximum number of steps to take on each contour
//  private
bool           pen;       //  whether or not the pen is down
} contourtask;

void drawcontour(contourtask *CT, real Level);
void framecontourplot(contourtask *CT);


//  N-by-N matrices

void solvetridiag(int N, real *A, real *B, real *C, real *D);


//  C-splines

//void drawcspline(int OFFSET, real *H, real *V, real *HT, real *VT, int SEGS);


//  Platonic solids

void framedodecahedron(window *W, vector *Offset);
void framebccwignerseitzcell(window *W, vector *Offset);
void framefccwignerseitzcell(window *W, vector *Offset);