Im trying to make a voxel engine similar to minecraft as a little learning experience and a way to learn some opengl. I have created a chunk class and I want to put all of the vertices for the whole chunk into a single VBO. I was previously only putting each block into a vbo and making a call to render each block. Anyways, I am a bit confused about how I can translate the coordinates of each block in the chunk when I'm putting all vertices into one vbo.

This is what I have at the moment.

public void putVertices(float tx, float ty, float tz) {
    float l_length = 1.0f;
    float l_height = 1.0f;
    float l_width = 1.0f;
    vertexPositionData.put(new float[]{
            xOffset + l_length + tx, l_height + ty, zOffset + -l_width + tz,
            xOffset + -l_length + tx, l_height + ty, zOffset + -l_width + tz,
            xOffset + -l_length + tx, l_height + ty, zOffset + l_width + tz,
            xOffset + l_length + tx, l_height + ty, zOffset + l_width + tz,

            xOffset + l_length + tx, -l_height + ty, zOffset + l_width + tz,
            xOffset + -l_length + tx, -l_height + ty, zOffset + l_width + tz,
            xOffset + -l_length + tx, -l_height + ty, zOffset + -l_width + tz,
            xOffset + l_length + tx, -l_height + ty, zOffset + -l_width + tz,

            xOffset + l_length + tx, l_height + ty, zOffset + l_width + tz,
            xOffset + -l_length + tx, l_height + ty,zOffset +  l_width + tz,
            xOffset + -l_length + tx, -l_height + ty,zOffset +  l_width + tz,
            xOffset + l_length + tx, -l_height + ty, zOffset + l_width + tz,

            xOffset + l_length + tx, -l_height + ty, zOffset + -l_width + tz,
            xOffset + -l_length + tx, -l_height + ty,zOffset +  -l_width + tz,
            xOffset + -l_length + tx, l_height + ty, zOffset + -l_width + tz,
            xOffset + l_length + tx, l_height + ty, zOffset + -l_width + tz,

            xOffset + -l_length + tx, l_height + ty, zOffset + l_width + tz,
            xOffset + -l_length + tx, l_height + ty, zOffset + -l_width + tz,
            xOffset + -l_length + tx, -l_height + ty, zOffset + -l_width + tz,
            xOffset + -l_length + tx, -l_height + ty,zOffset +  l_width + tz,

            xOffset + l_length + tx, l_height + ty,zOffset +  -l_width + tz,
            xOffset + l_length + tx, l_height + ty, zOffset + l_width + tz,
            xOffset + l_length + tx, -l_height + ty, zOffset + l_width + tz,
            xOffset + l_length + tx, -l_height + ty, zOffset + -l_width + tz

    });
}

public void createChunk() {
    vertexPositionData = BufferUtils.createFloatBuffer((24*3)*activateBlocks);

    Random random = new Random();
    for (int x = 0; x < CHUNK_SIZE; x++) {
        for (int y = 0; y < CHUNK_SIZE; y++) {
            for (int z = 0; z < CHUNK_SIZE; z++) {
                if(blocks[x][y][z].getActive()) {
                    putVertices(x*2.0f, y*2.0f, z*2.0f);
                }
            }
        }
    }

Whats any easy way to translate the vertices of each block into its correct position? I was previously using glTranslatef with each call to render block but this wont work now. What I am doing now also does not work, the blocks all render in stacks on top of each other and it looks like this:

http://i.imgur.com/NyFtBTI.png

Thanks