public void renderPreview(ShapeRenderer shapeRenderer) {
        shapeRenderer.begin();

        for (int side = 0; side < 6; ++side) {
            if (side == 0) {
                shapeRenderer.normal(0F, 1F, 0F);
            }

            if (side == 1) {
                shapeRenderer.normal(0F, -1F, 0F);
            }

            if (side == 2) {
                shapeRenderer.normal(0F, 0F, 1F);
            }

            if (side == 3) {
                shapeRenderer.normal(0F, 0F, -1F);
            }

            if (side == 4) {
                shapeRenderer.normal(1F, 0F, 0F);
            }

            if (side == 5) {
                shapeRenderer.normal(-1F, 0F, 0F);
            }

            renderInside(shapeRenderer, 0, 0, 0, side);
        }

        shapeRenderer.end();
    }