Invoice with special prices

How is it possible to add special prices to the invoice? I wanna see the original price and the special price... In the product.tpl i see for example the two variable $price and $special but how can I get them into order_invoice.tpl? Same question about discounts...

Thanks for your help

Basically when your customers confirm the order it will stored into database tables, like Product Details stored in order_product table and when your customers or you see its invoice it will display details from database. By default opencart is only storing products final price after discount in database so for special or discount you might need to add two columns into database and need to store special or discounted prices according so that you can display it on invoces.

The alternative way rather than adding two separate fields in the database amongst the order would be to extend the query where the order products are already queried from the core so to use all possible related product IDs with specials prices in order to show on the invoice. The only disadvantage with this is that specials are of course for limited time period and, later on, when trying to gather the information regarding specials, the order info may see the results as expired dates regarding those specials.