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circ.c

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/*
** ----------------------------------------------------------------
** circ.c  -  Circle primitive module.
**
** ----------------------------------------------------------------
*/

/*
** ---------------------------------------------------------------
** Global variables and symbols:
*/
#ifdef _WIN32
#include <windows.h>
#endif
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <GL/gl.h>
#include <GL/glu.h>

#include "prm.h"
#include "circ.h"
#include "cd.h"
#include "wd.h"
#include "dsp.h"

/*
** ---------------------------------------------------------------
** Local variables and symbols:
*/

#define CIRC_SEGS 32

#ifndef M_PI
#define M_PI 3.141592654
#endif

struct _circ {
  Coord         c;
  double        r;
 };



/*
** ---------------------------------------------------------------
** Private functions:
*/

static void circGetLateralNormal( Circ *circ, Coord *p, Coord *normal );

/*====================  circGetLateralNormal  ===================*/

static void circGetLateralNormal( Circ *circ, Coord *p, Coord *normal )
{
 double len;
 normal->x = p->x - circ->c.x;
 normal->y = p->y - circ->c.y;
 len = sqrt( normal->x*normal->x + normal->y*normal->y );
 normal->x /= len;
 normal->y /= len;
}

/*
** ---------------------------------------------------------------
** Public functions:
*/

/*=========================  circCreate  ========================*/

Circ *circCreate( void )
{
 Circ *circ;

/* Allocate memory for a new primitive.
 */
 circ = malloc( sizeof( Circ ) );
 if( circ == NULL )
  return( NULL );

/* Set default values for new primitive.
 */
 circ->c.x = 0.0;
 circ->c.y = 0.0;
 circ->r = 1.0;

 return( circ );
}

/*=========================  circDelete  ========================*/

void circDelete( Circ *circ )
{
 free( circ );
}

/*==========================  circRead  =========================*/

void circRead( Circ *circ, FILE *fd )
{
/*** COMPLETE HERE: 30 ***/
}

/*=========================  circWrite  =========================*/

void circWrite( Circ *circ, FILE *fd )
{
/*** COMPLETE HERE: 31 ***/
}

/*========================  circGetNPts  ========================*/

int circGetNPts( Circ *circ )
{
 return( 4 );
}

/*=======================  circSetCoords  =======================*/

void circSetCoords( Circ *circ, int id, double x, double y )
{
/*** COMPLETE HERE: 32 ***/
}

/*=======================  circGetCoords  =======================*/

void circGetCoords( Circ *circ, int id, double *x, double *y )
{
/*** COMPLETE HERE: 33 ***/
}

/*=======================  circSet1stPt  ========================*/

void circSet1stPt( Circ *circ, double x, double y )
{
/*** COMPLETE HERE: 34 ***/
}

/*=======================  circSet2ndPt  ========================*/

void circSet2ndPt( Circ *circ, double x, double y )
{
/*** COMPLETE HERE: 35 ***/
}

/*=======================  circPickArea  ========================*/

int circPickArea( Circ *circ, double x, double y )
{
/*** COMPLETE HERE: 36 ***/

 return( 0 );
}

/*======================  circPickVertex  =======================*/

int circPickVertex( Circ *circ, double x, double y, double tol,
                    int *id )
{
/*** COMPLETE HERE: 37 ***/

 return( 0 );
}

/*=======================  circPickSide  ========================*/

int circPickSide( Circ *circ, double x, double y, double tol,
                  int *id )
{
 return( 0 );
}

/*=======================  circTranslate  =======================*/

void circTranslate( Circ *circ, double dx, double dy )
{
/*** COMPLETE HERE: 38 ***/
}

/*====================  circTranslateVertex  ====================*/

void circTranslateVertex( Circ *circ, int id, double dx, double dy )
{
/*** COMPLETE HERE: 39 ***/
}

/*=====================  circTranslateSide  =====================*/

void circTranslateSide( Circ *circ, int id, double dx, double dy )
{
}

/*=========================  circGetBox  ========================*/

void circGetBox( Circ *circ, double *xmin, double *xmax, 
                             double *ymin, double *ymax )
{
/*** COMPLETE HERE: 40 ***/
}

/*====================  circDisplayBoundary  ====================*/

void circDisplayBoundary( Circ *circ )
{
/*** COMPLETE HERE: 41 ***/
}

/*====================  circDisplayInterior  ====================*/

void circDisplayInterior( Circ *circ )
{
/*** COMPLETE HERE: 42 ***/
}

/*=====================  circDisplaySolid  ======================*/

void circDisplaySolid( Circ *circ, double height )
{
/*** COMPLETE HERE: 42-A ***/
/*** Study function circDisplayZbuffer below ***/
/*** Use OpenGL functions ***/
}

/*======================  circHighltSolid  ======================*/

void circHighltSolid( Circ *circ, double height )
{
/*** COMPLETE HERE: 42-B ***/
/*** Use OpenGL functions ***/
}

/*====================  circDisplayZbuffer  =====================*/

void circDisplayZbuffer( Circ *circ, double height, long int color )
{
 Coord p[32];                     /* circle points */
 Coord normal;                    /* face normal vector */
 double alpha;                    /* circle angle */
 double delta = 2*M_PI/CIRC_SEGS; /* increment of circle angle */
 Coord  midpt;                    /* auxiliar lateral face mid point */
 int i;
 
/* Build circle points.
 */
 alpha = 0.0;
 for( i = 0; i < CIRC_SEGS; i++ )
 {
  p[i].x = circ->c.x + circ->r * cos( alpha );
  p[i].y = circ->c.y + circ->r * sin( alpha );
  alpha += delta;
 }

/* Display base circle.
 * To display means to project the face and send it to the zbuffer module.
 */
 for( i = 0; i < CIRC_SEGS; i++ )
 {
  dspZbfBeginPoly( color, 0.0, 0.0, -1.0 );
  dspZbfVertex( circ->c.x, circ->c.y, 0.0 );
  dspZbfVertex( p[(i+1)%CIRC_SEGS].x, p[(i+1)%CIRC_SEGS].y, 0.0 );
  dspZbfVertex( p[i].x, p[i].y, 0.0 );
  dspZbfEndPoly( );
 }

/* If the height of the primitive is null, return;
 */
 if( height == 0.0 )
 {
  return;
 }

/* Display top circle (send to zbuffer module).
 */
 for( i = 0; i < CIRC_SEGS; i++ )
 {
  dspZbfBeginPoly( color, 0.0, 0.0, 1.0 );
  dspZbfVertex( circ->c.x, circ->c.y, height );
  dspZbfVertex( p[(i+1)%CIRC_SEGS].x, p[(i+1)%CIRC_SEGS].y, height );
  dspZbfVertex( p[i].x, p[i].y, height );
  dspZbfEndPoly( );
 }

/* Display lateral faces (send to zbuffer module).
 */
 for( i = 0; i < CIRC_SEGS; i++ )
 {
  midpt.x = (p[i].x + p[(i+1)%CIRC_SEGS].x) * 0.5;
  midpt.y = (p[i].y + p[(i+1)%CIRC_SEGS].y) * 0.5;
  circGetLateralNormal( circ, &midpt, &normal );
  dspZbfBeginPoly( color, normal.x, normal.y, 0.0 );
  dspZbfVertex( p[i].x, p[i].y, height );
  dspZbfVertex( p[i].x, p[i].y, 0.0 );
  dspZbfVertex( p[(i+1)%CIRC_SEGS].x, p[(i+1)%CIRC_SEGS].y, 0.0 );
  dspZbfVertex( p[(i+1)%CIRC_SEGS].x, p[(i+1)%CIRC_SEGS].y, height );
  dspZbfEndPoly( );
 }
}

midpt, &normal );
  dspZbfBeginPoly( color, normal.x, normal.y, 0.0 );
  dspZbfVertex( p[i].x, p[i].y, height );
  dspZbfVertex( p[i].x, p[i].y, 0.0 );
  dspZbfVertex( p[(i+1)%CIRC_SEGS].x, p[(i+1)%CIRC_SEGS].y, 0.0 );
  dspZbfVertex( p[(i+1)%CIRC_SEGS].x, p[(i+1)%CIRC_SEGS].y, height );
  dspZbfEndPoly( );
 }
}

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