I have this piece of code, the main idea is to draw a robot arm and move it whenever a data is received ob the 9090 port using UDP.
I want to figure out why after displaying the robot arm, I have no message displayed on the console.
Moreover I want to know how to modify the code just after if(number%2 ==0) in order to move the arm.
#include <GL/glut.h>
#include <math.h>
#define BASE_HEIGHT 4.0/2
#define BASE_RADIUS 1.0/2
#define HEAD_HEIGHT 1.25/2
#define HEAD_RADIUS 0.75/2
#define NECK_HEIGHT 0.5/2
#define EYE_LEVEL 0.75/2
#define NOSE_LENGTH 0.5/2
#define LOWER_ARM_HEIGHT 2.0/2
#define LOWER_ARM_WIDTH 0.5/2
#define UPPER_ARM_HEIGHT 1.25/2
#define UPPER_ARM_WIDTH 0.5/2
#define ARM_TRANSLATION 0.22/2
#define alpha 0.0
#define pi 3.14159265
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <netdb.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <netdb.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#define BUFSIZE 2048
//***********************
struct sockaddr_in myaddr; /* our address */
struct sockaddr_in remaddr; /* remote address */
socklen_t addrlen = sizeof(remaddr); /* length of addresses */
int recvlen; /* # bytes received */
int fd; /* our socket */
unsigned char buf[BUFSIZE]; /* receive buffer */
#define SERVICE_PORT 9090
int a2i(unsigned char *s)
{
int sign=1;
if(*s == '-')
sign = -1;
s++;
int num=0;
while(*s)
{
num=((*s)-'0')+num*10;
s++;
}
return num*sign;
}
// The robot arm is specified by (1) the angle that the upper arm makes
// relative to the x-axis, called shoulderAngle, and (2) the angle that the
// lower arm makes relative to the upper arm, called elbowAngle. These angles
// are adjusted in 5 degree increments by a keyboard callback.
static int shoulderAngle = 0, elbowAngle = 0;
// Handles the keyboard event: the left and right arrows bend the elbow, the
// up and down keys bend the shoulder.
void special(int key, int, int) {
switch (key) {
case GLUT_KEY_LEFT: (elbowAngle += 5) %= 360; break;
case GLUT_KEY_RIGHT: (elbowAngle -= 5) %= 360; break;
case GLUT_KEY_UP: (shoulderAngle += 5) %= 360; break;
case GLUT_KEY_DOWN: (shoulderAngle -= 5) %= 360; break;
default: return;
}
glutPostRedisplay();
}
// wireBox(w, h, d) makes a wireframe box with width w, height h and
// depth d centered at the origin. It uses the GLUT wire cube function.
// The calls to glPushMatrix and glPopMatrix are essential here; they enable
// this function to be called from just about anywhere and guarantee that
// the glScalef call does not pollute code that follows a call to myWireBox.
void wireBox(GLdouble width, GLdouble height, GLdouble depth) {
glPushMatrix();
glScalef(width, height, depth);
glutWireCube(1.0);
glPopMatrix();
}
// Displays the arm in its current position and orientation. The whole
// function is bracketed by glPushMatrix and glPopMatrix calls because every
// time we call it we are in an "environment" in which a gluLookAt is in
// effect. (Note that in particular, replacing glPushMatrix with
// glLoadIdentity makes you lose the camera setting from gluLookAt).
void display() {
glClear(GL_COLOR_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
// Draw the upper arm, rotated shoulder degrees about the z-axis. Note that
// the thing about glutWireBox is that normally its origin is in the middle
// of the box, but we want the "origin" of our box to be at the left end of
// the box, so it needs to first be shifted 1 unit in the x direction, then
// rotated.
glRotatef((GLfloat)shoulderAngle, 0.0, 0.0, 1.0);
glTranslatef(1.0, 0.0, 0.0);
wireBox(2.0, 0.4, 1.0);
// Now we are ready to draw the lower arm. Since the lower arm is attached
// to the upper arm we put the code here so that all rotations we do are
// relative to the rotation that we already made above to orient the upper
// arm. So, we want to rotate elbow degrees about the z-axis. But, like
// before, the anchor point for the rotation is at the end of the box, so
// we translate <1,0,0> before rotating. But after rotating we have to
// position the lower arm at the end of the upper arm, so we have to
// translate it <1,0,0> again.
glTranslatef(1.0, 0.0, 0.0);
glRotatef((GLfloat)elbowAngle, 0.0, 0.0, 1.0);
glTranslatef(1.0, 0.0, 0.0);
wireBox(2.0, 0.4, 1.0);
glPopMatrix();
glFlush();
}
// Handles the reshape event by setting the viewport so that it takes up the
// whole visible region, then sets the projection matrix to something reason-
// able that maintains proper aspect ratio.
void reshape(GLint w, GLint h) {
glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(65.0, GLfloat(w)/GLfloat(h), 1.0, 20.0);
}
// Perfroms application specific initialization: turn off smooth shading,
// sets the viewing transformation once and for all. In this application we
// won't be moving the camera at all, so it makes sense to do this.
void init() {
glShadeModel(GL_FLAT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(1,2,8, 0,0,0, 0,1,0);
}
// Initializes GLUT, the display mode, and main window; registers callbacks;
// does application initialization; enters the main event loop.
int main(int argc, char** argv) {
/* create a UDP socket */
if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
perror("cannot create socket\n");
return 0;
}
/* bind the socket to any valid IP address and a specific port */
memset((char *)&myaddr, 0, sizeof(myaddr));
myaddr.sin_family = AF_INET;
myaddr.sin_addr.s_addr = htonl(INADDR_ANY);
myaddr.sin_port = htons(SERVICE_PORT);
if (bind(fd, (struct sockaddr *)&myaddr, sizeof(myaddr)) < 0) {
perror("bind failed");
return 0;
}
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowPosition(80, 80);
glutInitWindowSize(800, 600);
glutCreateWindow("Robot Arm");
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutSpecialFunc(special);
init();
glutMainLoop();
/* now loop, receiving data and printing what we received */
for (;;) {
printf("waiting on port %d\n", SERVICE_PORT);
recvlen = recvfrom(fd, buf, BUFSIZE, 0, (struct sockaddr *)&remaddr, &addrlen);
printf("received %d bytes\n", recvlen);
if (recvlen > 0) {
buf[recvlen] = 0;
printf("received message: \"%s\"\n", buf);
int number = a2i( buf );
if(number%2 ==0) {
printf("pair message: \"%s\"\n", buf);
}
}
}
/* never exits */
//*******************
}
