Vertex Buffer object

Hi
I have written a coding using opengl to draw 5 circle at a distance of 50 km each.

I have implemented this using vertex array , it is working fine
I am trying to do this using vertex buffer object, i have created vbo ,binded it with array vertices but i am not getting proper circle.

I am attaching my code with this if someone knows what mistake i am doing kindly reply

CODING

/////////////////Declartions///////////////
void createVBO(GLuint* vboId);
GLuint vboId;
float circlevertexarray[5000];

void circledata();
void display();

////////////////////Function to calculate circle vertices///////////////////
void circledata()
{
float v1,v2;
for(int no=1;no<6;no++)
{

                 for(float angle=0;angle&lt;360.0*(3.14/180);angle=angle+0.02)
                     {
                        v1=no*0.42*cos(angle);
                        v2=no*0.42*sin(angle);
                        circlevertexarray[(j*2)+0]=v1;
                        circlevertexarray[(j*2)+1]=v2;
                        j++;
                     }
               }
              indices=j+1;
             printf("%d

",indices);

}

//////////////////////Function to create VBO//////////////////////////////
void createVBO(GLuint* vboId)
{
// create buffer object
glGenBuffers(1,vboId);
glBindBuffer(GL_ARRAY_BUFFER, vboId);
// initialize buffer object
glBufferData(GL_ARRAY_BUFFER,2
indices*sizeof(float),circlevertexarray ,GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
#if 1
int bufferSize = 0;

glGetBufferParameteriv(GL_ARRAY_BUFFER, GL_BUFFER_SIZE, &bufferSize);

if(indices != bufferSize)
{
   glDeleteBuffersARB(1, vboId);
   vboId = 0;
    printf("datasize mismatch

");
}
else
{
printf("matching
");
}
#endif
}

/////////////////Main///////////////////////////////////
int main(int argc, char** argv)
{
initGL(argc, argv);
circledata();
createVBO(&vboId);

 MulticastInit();
 threadid=pthread_create(&Receivethread,NULL,&sweep,NULL);
 glutDisplayFunc(display);
 glutMainLoop();

}

//////////////////////DISPLAY Function/////////////////
void display()
{

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
 while(1)
 {
            //usleep(10000);
             glClearColor(0.0,0.0,0.0,1.0);

             glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

////////////////////Vertex Buffer Object////////////////////////
#if 1
glColor3f(1.0,1.0,1.0);
glBindBuffer(GL_ARRAY_BUFFER,vboId);
glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(2, GL_FLOAT, 0,0);
glDrawArrays(GL_POINTS,0,indices);
glDisableClientState(GL_VERTEX_ARRAY);
glBindBuffer(GL_ARRAY_BUFFER, 0);
#endif

///////////////////////Vertex array//////////////////////////
#if 0
glColor3f(1.0f,1.0f,1.0f);
glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(2, GL_FLOAT, 0,circlevertexarray );
glDrawArrays(GL_POINTS,0,indices);
glDisableClientState(GL_VERTEX_ARRAY);

#endif
}
}

.

Thank You
 Janani

Is indices a global variable?
As a side note you need to tidy up your use of global and local variables IMO. :slight_smile:

What are you actually seeing when you draw?

On the surface your GL code looks ok… Perhaps try swapping the bind and enable around in the draw function?

I suspect the problem has something to with initialising / enabling the VBO as your data creation obviously works for vertex arrays.

Also, just to be sure, do you check that you get a valid buffer ID back when you create it?

Thank you for ur reply…

Yes indices is a global variable
When drawing i see some half drawn 2 circle.
I got vboid as 1.

I am attaching entire coding.

// includes, system
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <pthread.h>
#include <sys/time.h>
#include <unistd.h>

// includes, GL
#include <GL/glew.h>

#if defined (APPLE) || defined(MACOSX)
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif

// includes

#include <rendercheck_gl.h>

///////////////////////////constants///////////////////
#define PRT 3200;
#define RANGECELL 6000;
const unsigned int window_width =700;
const unsigned int window_height =700;

//////////////////User Defined Function////////////////
void MulticastInit();
void circledata();
void display();
void *sweep(void * );
void *video(void *);
int SetTimer(struct timeval &tv, int usec);
int CheckTimer(struct timeval &tv, time_t usec);
void Reverse2Byte(char data[],int number);

//////////////////// GL functionality////////////////////
bool initGL(int argc, char** argv);
void createVBO(GLuint* vboId);
void deleteVBO(GLuint* vboId);
///////////////////// declaration///////////////////

///////////////////GLDeclaration////////////////////
GLuint vboId;
GLuint idcheck;

int threadid;
int sockfd;
struct sockaddr_in address;
struct ip_mreq group;
int len,result;
int reuse=1;
char buffer[200];
pthread_t Receivethread;
struct timeval tv;
int cpivalue=0;
int i;
int indices=0;
float circlevertexarray[5000];
int j=0;
int videodata[3200][6000];
static int prtcounter,rangecellcounter;
struct senddata
{
unsigned short m[10];
}swapeddata;
int count;
////////////////////////circledata////////////////////////////
void circledata()
{
float v1,v2;
for(int no=1;no<6;no++)
{

                 for(float angle=0;angle&lt;360.0*(3.14/180);angle=angle+0.02)
                     { 
                        v1=no*0.42*cos(angle);
                        v2=no*0.42*sin(angle);   
                        circlevertexarray[(j*2)+0]=v1;     
                        circlevertexarray[(j*2)+1]=v2;    
                        j++;
                     }       
               }
              indices=j+1;
             printf("%d

",indices);

}

////////////////////////create VBO///////////////////////////////

void createVBO(GLuint* vboId)
{
// create buffer object
glGenBuffers(1,vboId);
glBindBuffer(GL_ARRAY_BUFFER, vboId);
// initialize buffer object
glBufferData(GL_ARRAY_BUFFER,2
indices*sizeof(float),circlevertexarray ,GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
#if 1
int bufferSize = 0;

glGetBufferParameteriv(GL_ARRAY_BUFFER, GL_BUFFER_SIZE, &bufferSize);

if(indices != bufferSize)
{
   glDeleteBuffersARB(1, vboId);
   vboId = 0;
    printf("datasize mismatch

");
}
else
{
printf("matching
");
}
#endif
}

/////////////////////////MulticastInit///////////////////////////

void MulticastInit()
{
printf("Hello I am Multicast Init
“);
//Open Socket//
sockfd=socket(AF_INET,SOCK_DGRAM,0);
if(sockfd < 0)
{
perror(“Opening datagram socket error”);
exit(1);
}
else
{
printf(”…Socket Opened Successfully…
");
printf("sockfd=%d
",sockfd);
}

 //************Set Socket For reuse********//
if(setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR,(char *)&reuse, sizeof(reuse))&lt;0)
{
 perror("Reuse Error

“);
}
else
{
printf(”…Reuse Socket Set Successfully…
");
}

 address.sin_family=AF_INET;
 address.sin_port=htons(2222);
 address.sin_addr.s_addr=INADDR_ANY;
 len=sizeof(struct sockaddr);
 printf("Length=%d

",len);

 //**********Connect Socket***********//
 if(bind(sockfd, (struct sockaddr *)&address, sizeof(address))&lt;0)
 {
   printf("Socket Connection Failed 

“);
close(sockfd);
exit(1);
}
else
{
printf(”--------Socket Binded-----------
");
}

    group.imr_multiaddr.s_addr = inet_addr("225.0.0.1");
    group.imr_interface.s_addr = inet_addr("192.168.100.185");
    if(setsockopt(sockfd, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char *)&group, sizeof(group)) &lt; 0)
      {
         perror("Adding multicast group error");
         close(sockfd);
         exit(1);
      }
     else
       {
           printf("----------Adding Multicast group Ok----

");
}

printf("--------Mul check------------
");
}

////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
// Program main
////////////////////////////////////////////////////////////////////////////////
int main(int argc, char** argv)
{
initGL(argc, argv);
circledata();
createVBO(&vboId);

 MulticastInit();
 threadid=pthread_create(&Receivethread,NULL,&sweep,NULL);
 glutDisplayFunc(display);
 glutMainLoop();

}

////////////////////////////////////////////////////////////////////////////////
//! Initialize GL
////////////////////////////////////////////////////////////////////////////////
bool initGL(int argc, char **argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE);
glutInitWindowSize(window_width, window_height);
glutCreateWindow(“Test”);
glutDisplayFunc(display);

// initialize necessary OpenGL extensions
glewInit();

float aspectratio=window_width/window_height;

// default initialization
glClearColor(0.0, 0.0, 0.0, 1.0);

// viewport
glViewport(0, 0, window_width, window_height);

// projection
glMatrixMode(GL_PROJECTION);
glLoadIdentity();

glOrtho(-3.0,3.0,-3.0/aspectratio,3.0/aspectratio,-200.0,200.0);
// glOrtho(-3.0,3.0,-3.0,3.0,-200.0,200.0);

glMatrixMode(GL_MODELVIEW);
glLoadIdentity();  

}

////////////////////////////////////////////////////////////////////////////////
//! Display callback
////////////////////////////////////////////////////////////////////////////////

void display()

{

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
 while(1)
 {
            //usleep(10000);      
             glClearColor(0.0,0.0,0.0,1.0);

             glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

#if 1
glColor3f(1.0,1.0,1.0);
glBindBuffer(GL_ARRAY_BUFFER,vboId);
// glEnableClientState(GL_NORMAL_ARRAY);
glEnableClientState(GL_VERTEX_ARRAY);
// glNormalPointer(GL_FLOAT,0,(void*)sizeof(indices));
glVertexPointer(2, GL_FLOAT,0,0);
glDrawArrays(GL_POINTS,0,indices);
glDisableClientState(GL_VERTEX_ARRAY);
// glDisableClientState(GL_NORMAL_ARRAY);
glBindBuffer(GL_ARRAY_BUFFER, 0);
#endif

#if 0
glColor3f(1.0f,1.0f,1.0f);
glEnableClientState(GL_NORMAL_ARRAY);
glEnableClientState(GL_VERTEX_ARRAY);
glNormalPointer(GL_FLOAT,0,circlevertexarray);
glVertexPointer(2, GL_FLOAT, 0,circlevertexarray );
glDrawArrays(GL_POINTS,0,indices);
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_NORMAL_ARRAY);

            glBegin(GL_LINES);
              glVertex2f(0.0,0.0);
              glVertex2f(0.0,2.1);
              glVertex2f(0.0,0.0);
              glVertex2f(2.1,0.0);
              glVertex2f(0.0,0.0);
              glVertex2f(0.0,-2.1);
              glVertex2f(0.0,0.0);
              glVertex2f(-2.1,0.0);
            glEnd();

#endif
#if 0

             //circles
   	         glColor3f(1.0,1.0,1.0);
         glBegin(GL_POINTS);
         for(int i=0;i&lt;6;i++)
         {
 		    for(float angle=0;angle&lt;360.0*(3.14/180);angle=angle+0.0157)
  		     {
    	       glVertex2f(i*0.42*cos(angle),i*0.42*sin(angle) );
   		      }
  	         }
             glEnd();




            //line
        glBegin(GL_LINES); 
          glVertex2f(0.0,0.0);
          glVertex2f(0.0,2.1);
          glVertex2f(0.0,0.0);
          glVertex2f(2.1,0.0);
          glVertex2f(0.0,0.0);
          glVertex2f(0.0,-2.1);
          glVertex2f(0.0,0.0);
          glVertex2f(-2.1,0.0);
            glEnd();

#endif
///////////////////////
#if 0

           glBegin(GL_QUAD_STRIP);
            glColor3f(0.0,0.7,0.0);
            glVertex2f(0,0);
            glVertex2f((5*0.42)*sin((cpivalue*0.0157)),(5*0.42)*cos((cpivalue*0.0157)));
            glColor3f(0.0,0.6,0.0);
            glVertex2f(0,0);
            glVertex2f((5*0.42)*sin(((cpivalue-10)*0.0157)),(5*0.42)*cos(((cpivalue-10)*0.0157)));
            glColor3f(0.0,0.5,0.0);
        glVertex2f(0,0);
        glVertex2f((5*0.42)*sin(((cpivalue-20)*0.0157)),(5*0.42)*cos(((cpivalue-20)*0.0157)));
            glColor3f(0.0,0.0,0.0);
            glVertex2f(0,0);
        glVertex2f((5*0.42)*sin(((cpivalue-30)*0.0157)),(5*0.42)*cos(((cpivalue-30)*0.0157)));
           glEnd();

#endif
glutSwapBuffers();

}//while

}//Display Function

i also get only part of my mesh displayed… just now i posted my problem… You got any solution…??

I am wondering if this is your problem and you are drawing an invalid VBO because you have deleted it:

glGetBufferParameteriv(GL_ARRAY_BUFFER, GL_BUFFER_SIZE, &bufferSize);

if(indices != bufferSize)
{
glDeleteBuffersARB(1, vboId);

GL_BUFFER_SIZE is your size in bytes of the VBO, and indices is the number of indices. So they will not be the same…

Thank you very much,
Problem solved, I am getting the circle properly.

It was Indices and buffersize mismatch.

Now i will proceed with FBO concept, I want to implement Multilayering concept in my application.

Bye…