Question

I am developing a game where similar objects are rendered on the screen. The problem is that every time a new object is added, more vertices needs to be handled, so FPS decrease.

Since I am a beginner with openGl, I have some general ideas about improving performance, I just don’t know what openGl allows me to do.

1. Since most of my objects are identical(same number of vertices, same colors, same uvs and same normals), but only the position and rotation of the objects are different, is it possible to send the vertices for similar objects only once, on each frame render , and then call drawElements for all objects and modify only the objects positions?

2. Is it possible to go even further, and upload those similar vertices, only once when the scene is 1st created, and on each frame render just call drawElements for each object?

Currently, I am sending the vertices for each object like this:

.......
gl.glNormalPointer(GL10.GL_FLOAT, 0, normals);
gl.glColorPointer(4, GL10.GL_UNSIGNED_BYTE, 0, colors);
gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertices);
gl.glPushMatrix();
gl.glTranslatef(position);
gl.glRotatef(rotation);
gl.glScalef(scale);    
gl.glDrawElements(renderType,nr,GL10.GL_UNSIGNED_SHORT, faces);
gl.glPopMatrix();
........

I am thinking I should do someting like this:

.......
gl.glNormalPointer(GL10.GL_FLOAT, 0, normals);
gl.glColorPointer(4, GL10.GL_UNSIGNED_BYTE, 0, colors);
gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertices);
for(eachObject)
{
gl.glPushMatrix();
gl.glTranslatef(position);
gl.glRotatef(rotation);
gl.glScalef(scale);
gl.glDrawElements(renderType,nr,GL10.GL_UNSIGNED_SHORT, faces);
gl.glPopMatrix();
........
}

Answer 1

1. Yes
2. Yes (even better)

Your second code example looks exactly like what you should be doing.

There’s no reason you’d need to upload the vertices more than once, doing it on initialization should be sufficient. After that just set the pointers any time you want to render. You can call glDrawElements as many times as you want with different translations/rotations.