PolygonMake

Syntax

struct PolygonData *PolygonMake(int sze,int (*bbox)(void *x, void *y,int s));

Header

general/polygon.h

Library

poly

Description

The PolygonMake function creates a polygon group.

A polygon group can be defined in a coordinate system with an arbitrary number of dimensions, defined using any data type. The argument sze defines the number of bytes required to store a point.

The final argument bbox, is a pointer to a function of the form:

int bbox(void *x,void *y,int s);

This function is called each time a new point is added to a polygon and its purpose is to calculate the bounding box of the polygon.

The first argument x is a pointer to the point added to the polygon, while the second argument y is an array pointer consisting of two elements. The first defines the lower limits of the bounding box, while the second defines the upper limits. In the case of a two dimensional polygon the two elements would define the bottom left and top right hand co-ordinates of the bound box.

The final argument s defines the number of bytes required to store a point.

Returns

Returns a pointer to the new polygon group on success. On error, a NULL pointer is returned.

Errors

On error, a NULL pointer is returned.

Example

Source Code: PolygonMake.c

/* PolygonMake.c
   =============
   Author: R.J.Barnes
 Copyright (c) 2012 The Johns Hopkins University/Applied Physics Laboratory

This file is part of the Radar Software Toolkit (RST).

RST is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.

Modifications:




#include <stdio.h>
#include <stdlib.h>
#include "rtypes.h"
#include "rxml.h"
#include "option.h"
#include "rfbuffer.h"
#include "rplot.h"
#include "polygon.h"
#include "rmap.h"

struct PolygonData *poly;

float fx[256],fy[256];
int t[256];

int stream(char *buf,int sze,void *data) {
  FILE *fp;
  fp=(FILE *) data;
  fwrite(buf,sze,1,stdout);
  return 0;
} 

int main(int argc,char *argv[]) {

  struct Rplot *rplot=NULL;

  float wdt=400,hgt=400;

  unsigned int bgcol=0xffffffff;
  unsigned int fgcol=0xff000000;

  int i,j;
  int type;
 
  float pnt[2]; 
  float *ptr;

  poly=PolygonMake(sizeof(float)*2,PolygonXYbbox);
 
  PolygonAddPolygon(poly,1);

  pnt[0]=0.1;
  pnt[1]=0.1;
  PolygonAdd(poly,pnt,0);

  pnt[0]=0.9;
  pnt[1]=0.1;
  PolygonAdd(poly,pnt,0);

  pnt[0]=0.9;
  pnt[1]=0.9;
  PolygonAdd(poly,pnt,0);

  pnt[0]=0.1;
  pnt[1]=0.9;
  PolygonAdd(poly,pnt,0);

  PolygonAddPolygon(poly,2);

  pnt[0]=0.2;
  pnt[1]=0.5;
  PolygonAdd(poly,pnt,0);

  pnt[0]=0.5;
  pnt[1]=0.2;
  PolygonAdd(poly,pnt,0);

  pnt[0]=0.8;
  pnt[1]=0.5;
  PolygonAdd(poly,pnt,0);

  pnt[0]=0.5;
  pnt[1]=0.8;
  PolygonAdd(poly,pnt,0);

 
  rplot=RplotMake();
  RplotSetText(rplot,stream,stdout);   
  RplotMakeDocument(rplot,"PolygonMake","1",wdt,hgt,24);

  RplotMakePlot(rplot,"PolygonMake",wdt,hgt,24);

  RplotRectangle(rplot,NULL,0,0,wdt,hgt,
                  1,bgcol,0x0f,0,NULL);

  for (i=0;i<poly->polnum;i++) {
    type=PolygonReadType(poly,i);
    if (type==1) fgcol=RplotColor(255,0,0,255);
    if (type==2) fgcol=RplotColor(0,255,0,255);

    for (j=0;j<poly->num[i];j++) {
      ptr=(float *) PolygonRead(poly,i,j);
      fx[j]=ptr[0]*wdt;
      fy[j]=ptr[1]*hgt;
      t[j]=0;
    }
    RplotPolygon(rplot,NULL,0,0,poly->num[i],fx,fy,t,
                  1,fgcol,0x0f,0,NULL);
  }

  RplotEndPlot(rplot);
  RplotEndDocument(rplot);
  return 0;
}