Fast Opengl wireFrame grid

The most optimized way would be:

 - To use GL_LINE_STRIP and/or GL_LINE_LOOP where possible;
 - Hardcode the vertices (rather than use iteration) - [then just use glScale*() to change the size];

and:

 - Use display lists for further program optimization.

ok can you code that please

cool. But can you put comment on each line loop so i can understand what you are actually drawing? I'm confused.

I understand here.. ok well can the code be adjusted so I can choose the number of division on each side?

> can the code be adjusted so I can choose the number of division on each side?

Certainly.

The reason I had not made room for the implementation of multiple divisions, is because it would require iterations - which will add slight overhead to your program (the opposite of optimization ;)).

However, this should perform reasonably well:


void renderWireFrameCubeGrid(int k)
{
            float o=k/2.0f;
            int i;
           
            glTranslatef(-o,-o,o);
           
           
            for(i=0; i<k; i++)
            {
                glBegin(GL_LINE_LOOP);
                glVertex3f(0,i,0);
                glVertex3f(k,i,0);
                glVertex3f(k,i,-k);
                glVertex3f(0,i,-k);
                glEnd();
            }
            for(i=0; i<=k; i++)
            {
                glBegin(GL_LINE_LOOP);
                glVertex3f(0,0,-i);
                glVertex3f(0,k,-i);
                glVertex3f(k,k,-i);
                glVertex3f(k,0,-i);
                glEnd();
            }
            for(i=0; i<=k; i++)
            {
                glBegin(GL_LINE_LOOP);
                glVertex3f(i,0,0);
                glVertex3f(i,k,0);
                glVertex3f(i,k,-k);
                glVertex3f(i,0,-k);
                glEnd();
            }
           
            glTranslatef(o,o,-o);
}


As an example: for a 6x6x6 cube, call:

renderWireFrameCubeGrid(6);

You could possibly improve performance by using display lists;

Firstly you define the display list -- this should be done outside of the Display() function - generally in the Init() function:

// create the display list:
listN6 = glGenLists(1);
glNewList(listN, GL_COMPILE);
renderWireFrameCubeGrid(6);
glEndList();


Where listN is defined globally (outside of any functions), like so:

GLuint listN;


Then to display this item in your Display() function:

// [translate, rotate, scale, .., here if necessary], then load the list (draw the cube):
glCallList(listN6);


This should eliminate a fair bit of math that the computer would otherwise have to keep doing on each graphic-loop.

Sorry, I messed up the variable name a bit;
all occurances of "listN" should be "listN6" [in this example].