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Janani
11-05-2009, 09:43 PM
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<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\n",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(floa t),circlevertexarray ,GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
#if 1
int bufferSize = 0;

glGetBufferParameteriv(GL_ARRAY_BUFFER, GL_BUFFER_SIZE, &amp;bufferSize);

if(indices != bufferSize)
{
glDeleteBuffersARB(1, vboId);
vboId = 0;
printf("datasize mismatch\n");
}
else
{
printf("matching\n");
}
#endif
}


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

MulticastInit();
threadid=pthread_create(&amp;Receivethread,NULL,&amp;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