sphere_draw.c

void drawsphere()
{
  #define PI 3.14159265358979323846f
  int width = 32;
  int height = 16;

  float theta, phi, *dat;
  int i, j, t, ntri, nvec, *idx;

  nvec = (height-2)* width+2;
  ntri = (height-2)*(width-1)*2;

  dat = (float*) malloc( nvec * 3*sizeof(float) );
  idx =   (int*) malloc( ntri * 3*sizeof(int)   );

  for( t=0, j=1; j<height-1; j++ )
  for(      i=0; i<width; i++ )
  {
    theta = float(j)/(height-1) * PI;
    phi   = float(i)/(width-1 ) * PI*2;
    dat[t++] =  sinf(theta) * cosf(phi);
    dat[t++] =  cosf(theta);
    dat[t++] = -sinf(theta) * sinf(phi);
  }
  dat[t++]=0; dat[t++]= 1; dat[t++]=0;
  dat[t++]=0; dat[t++]=-1; dat[t++]=0;

  for( t=0, j=0; j<height-3; j++ )
  for(      i=0; i<width-1; i++ )
  {
    idx[t++] = (j  )*width + i  ;
    idx[t++] = (j+1)*width + i+1;
    idx[t++] = (j  )*width + i+1;
    idx[t++] = (j  )*width + i  ;
    idx[t++] = (j+1)*width + i  ;
    idx[t++] = (j+1)*width + i+1;
  }
  for( i=0; i<width-1; i++ )
  {
    idx[t++] = (height-2)*width;
    idx[t++] = i;
    idx[t++] = i+1;
    idx[t++] = (height-2)*width+1;
    idx[t++] = (height-3)*width + i+1;
    idx[t++] = (height-3)*width + i;
  }

  glEnableClientState(GL_VERTEX_ARRAY);
  glEnableClientState(GL_NORMAL_ARRAY);
  glVertexPointer(3,GL_FLOAT,0,dat);
  glNormalPointer(GL_FLOAT,0,dat);
  glDrawElements(GL_TRIANGLES, ntri*3, GL_UNSIGNED_INT, idx );
  glDisableClientState(GL_VERTEX_ARRAY);
  glDisableClientState(GL_NORMAL_ARRAY);

  free(idx);
  free(dat);
}