/*******************************************************
*    PROCEDURES TO DRAW A 3D CURVE IN SPACE X,Y,Z      *
* ---------------------------------------------------- *
* Ref.: "From Unit GRAPH3D.PAS By Robert DONY - MASSON *
*        Paris, 1990 - Graphisme dans le plan et dans  *
*        l'espace en Turbo Pascal 4.0" [BIBLI 12].     *
*                                                      *
*             Visual C++ Release By J-P Moreau, Paris. *
*                        (www.jpmoreau.fr)             *
*******************************************************/
#include "stdafx.h"
#include <math.h>

#define  echelle  1.35
#define  bord     15

#define  perspective  1
#define  parallele    2

double de,phi,rho,theta;
double aux1,aux2,aux3,aux4;
double aux5,aux6,aux7,aux8;
double xobs,yobs,zobs;
double xproj,yproj;
int    xscreen,xscreenold,yscreen,yscreenold;

int  projection;
int  MaxX, MaxY;
int  xgclot,xdclot,ybclot,yhclot;


//define client drawing zone in screen pixels
void Cloture(int c1,int c2,int c3,int c4) {
  xgclot=c1;
  xdclot=c2;
  ybclot=c3;
  yhclot=c4;
}

//calculate auxiliary projection variables
void InitProj()  {  
  double pi,th,ph;
  pi=3.1415926535;
  th=pi*theta/180; ph=pi*phi/180;
  aux1=sin(th); aux2=sin(ph); aux3=cos(th); aux4=cos(ph);
  aux5=aux3*aux2; aux6=aux1*aux2; aux7=aux3*aux4; aux8=aux1*aux4;
}

//projection to screen (xproj,yproj)
void Projette(double x,double y,double z) {
  xobs=-x*aux1+y*aux3; yobs=-x*aux5-y*aux6+z*aux4;
  if (projection==perspective) {
    zobs=-x*aux7-y*aux8-z*aux2+rho;
    xproj=de*xobs/zobs; yproj=de*yobs/zobs;
  }
  else {
    xproj=de*xobs; yproj=de*yobs;
  }
}

void DrawLine(CClientDC *P,int ix1,int iy1,int ix2,int iy2) {
  P->MoveTo(ix1,iy1);
  P->LineTo(ix2,iy2);
}

//draw a line from current point xscreenold,yscreenold 
void LineXYZ(CClientDC *P,double x,double y,double z) {
  Projette(x,y,z);
  xscreen=(int) floor(xproj*echelle+(MaxX/2));
  yscreen=(int) floor((MaxY/2)-yproj);
  if (xscreen>=0 && xscreen<=MaxX && yscreen>=0 && yscreen <=MaxY) {
    DrawLine(P,xscreenold,yscreenold,xscreen,yscreen);
    //update current point
    xscreenold=xscreen; yscreenold=yscreen;
  }
}

//change current point with pen up
void MoveXYZ(double x,double y,double z) {
  Projette(x,y,z);
  xscreen=(int) floor(xproj*echelle+(MaxX/2));
  yscreen=(int) floor((MaxY/2)-yproj);
  xscreenold=xscreen; yscreenold=yscreen;
}

//draw a frame around drawing zone
void Bordure(CClientDC *P) {
  DrawLine(P,bord,bord,MaxX-bord,bord);
  DrawLine(P,MaxX-bord,bord,MaxX-bord,MaxY-bord);
  DrawLine(P,MaxX-bord,MaxY-bord,bord,MaxY-bord);
  DrawLine(P,bord,MaxY-bord,bord,bord);
}

//draw 3 axes Ox,Oy,Oz
void Axes(CClientDC *P,double x,double y,double z)  {   
  MoveXYZ(0,0,0); LineXYZ(P,x,0,0);
  xscreen+=5; yscreen+=5;
  P->TextOut(xscreen,yscreen,"X",1);
  MoveXYZ(0,0,0); LineXYZ(P,0,y,0);
  xscreen+=5; yscreen+=5;
  P->TextOut(xscreen,yscreen,"Y",1);
  MoveXYZ(0,0,0); LineXYZ(P,0,0,z);
  xscreen+=10; yscreen-=5;
  P->TextOut(xscreen,yscreen,"Z",1);
}

//end of file graph3d.cpp