event example

//extending from net.minecraft.client.gui.GuiScreen allows me to get the methods in that class. EG drawCenteredString used in this example

    public EventRenderHud(Minecraft mc) {
        super(mc);
    }

@SubscribeEvent
    public void doRenderOverlay(RenderGameOverlayEvent event) {
        if(!mc.thePlayer.capabilities.isCreativeMode) {
            renderPlayerInfo(mc.thePlayer.getHealth(), mc.thePlayer.experienceLevel);
        }
    }

    private void renderPlayerInfo(float health, float exp) {
        DecimalFormat df = new DecimalFormat("#0.#");
        String currentHealth = df.format(health);
        String currentLevel = exp.ToString();
        GL11.glPushMatrix();
            this.drawCenteredString(this.mc.fontRenderer, currentLevel, 45, 47, this.textShadow);
            this.drawCenteredString(this.mc.fontRenderer, currentHealth, 107, 22, this.textShadow);
        GL11.glPopMatrix();
    }