Reading from a text file and plotting using GNU libplot - c

Question

I've made a program that reads from a file, and alphabetically sorts names contained within the file. The file contains planet names, mass, size, color, primary body, positions x,y,z and velocity x,y,z. I'm now trying to plot each planet using this file, but I'm unsure how to go about doing that. I'm using GNU libplot to plot the planets. I'm thinking that I need to use a loop and fscanfs to get the x and y coordinates (can omit Z for now) to plot each planet.
Here's my current code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define NAMES 20
struct planets{ //sets up initial characters and doubles to place into body.
char primaryBody[NAMES];
char name[NAMES];
char color[NAMES];
double mass;
double size;
double posx, posy, posz;
double velx, vely, velz;
};
struct planets body[100];
int readData(FILE* fd){ //This reads the file solarsystem.txt and fills array
int current = 0;
char line[201];
char cmpline[2] = "#";
do{
fgets(line, 200, fd); // Makes sure that the number of bytes written dont overflow your character.
}while((strlen(line)<2)||(strncmp(line, cmpline, 1))==0);
sscanf(line, "%s %lf %s %lf %s", body[current].name, &body[current].mass, body[current].color, &body[current].size, body[current].primaryBody);
fscanf(fd, "%lf %lf %lf", &body[current].posx, &body[current].posy, &body[current].posz);
fscanf(fd, "%lf %lf %lf", &body[current].velx, &body[current].vely, &body[current].velz);
current++;
while(!feof(fd)){//Runs the loop until the end of the file is met.
fscanf(fd, "%s %lf %s %lf %s", body[current].name, &body[current].mass, body[current].color, &body[current].size, body[current].primaryBody);
fscanf(fd, "%lf %lf %lf", &body[current].posx, &body[current].posy, &body[current].posz);
fscanf(fd, "%lf %lf %lf", &body[current].velx, &body[current].vely, &body[current].velz);
current++;
}
return current;
}
void sortNames(int planetNames){ //traditional bubble sorting code, with slight modification.
struct planets temp[1];
for(int i=0; i<(planetNames);i++){
for(int j=0; j<(planetNames-1); j++){
if (strcmp(body[j].name, body[j+1].name)>0){
temp[0] = body[j];
body[j] = body[j+1];
body[j+1] = temp[0];
}
}
}
void printBodies(int sortNames){// code to print out the sorted file.
int planetNames = sortNames;
printf("Name Mass Color Size Primary Body\n");
printf("_____________________________________________\n");
for(int i=0; i<(planetNames); i++){
printf("%-8s %1.4E %-6s %.2lf %s\n", body[i].name, body[i].mass, body[i].color, body[i].size, body[i].primaryBody);
}
}
int main(int argc, char *argv[]){/*runs the different structs, and if file not available, will tell the user.*/
FILE *fd;
fd = fopen (argv[1], "r");
if(!fd){
printf("File not available, or user did not type file name.\n");
return 1;
}
int planetNames=readData(fd);
sortNames(planetNames);
printBodies(planetNames);
findMax(planetNames);
return 0;
}