First off, don't even bother with transparencies if the model you're using doesn't have an interior. If it does then great - for this tutorial we're going to look at the GWR coaches that go behind Pendennis Castle and are also the base for my BR Blue and Grey coach set.

Transparencies are done in something called an Alpha Layer. They can only be done in a TGA (Targa) file so now is the time to abandon the BMP and make our textures in the TGA file format.

In Paintshop Pro terms, we're looking for the 'Mask'.

Without any further delay, let's move in to making a couple of windows on the Pendennis GWR stock transparent. The first thing we need to do is just put a coach into its own directory so that we aren't messing around with the stock that came with the game and then make a few changes to the coaches so that the transparency that's already there vanishes (very easy to do, trust me :) ).

The copying bit is fairly well the same old drill - after copying the PENDENNIS directory I deleted all files to do with the Steam locomotive as we aren't worrying about that and then renamed the files by replacing 'gwr' with 'ukts' - so, gwrluggcar.wag becomes uktsluggcar.wag.

You'll also need to edit the .SD and the .WAG files to change the GWR bits to UKTS.

Finally, remember to create an images directory and copy the following three files from SAMPLES in to it:

Let's see what GWRCARRIAGESMASTER.TGA looks like before we begin:

Let's load GWRCARRIAGESMASTER.TGA into PSP and do some initial edits...

A few quick edits get rid of a bunch of windows and the middle doors in the buffet car...

And finally,

Before we go on, let's just make sure we're clear on how those steps were achieved.

First I used copy and paste to take an area of the brown and cream that was clear of windows or any special artifacts and used that to remove the doors. Then I used just the cream portion to remove the windows - I did that because there are some artifacts along the lower side of the coach in the brown portion and it's easier to just ignore them than have to put them back or work around them.

That got you the first step, then next step was to copy and paste the three windows along the length of the coach. In order to ensure the spacing was correct I overlapped the left hand window to the right most window on the coach each time (so effectively we only gained two new windows with each paste).

Next let's change the colour of the brown to a crimson red - yup, we're looking at Blood and Custard here folks!

To make this colour change, I used the Hue Map adjuster tool. I set all the sliders to RED (the top setting) and then set Saturation to 20 and Lighting to 10. It's not great but the focus in this tutorial isn't on getting the colours right, I just want to get a texture that doesn't look too bad :)

I also applied a +20 brightness adjuster on the yellow just to make it a bit lighter.

That's as much as we're going to do on the coaches - let's take a look at our creation in Train Sim and see if we can see any immediate problems...

When we load this in to Train Sim we see a problem...

You might not be able to see it too well on this reduced image - but if you number the windows from left to right starting with one, then windows 3, 4, 5 and 6 all appear to be darker than the rest. Further, between 2 and 3 there is a light mark that looks odd. What's this all about?

This is where the transparencies used to be for the coaches we just modified. In order to fix this we need to go into the Alpha Layer and make some modifications so that the windows are still in the right place.

Two Kinds

There are two kinds of Transparency - if you convert your textures with the -trans option to MAKEACE then you will either have completely transparent or completely opaque. This is great for when you don't want things to be there at all - such as making ladders (why use lots of polygons when you can just have a flat face and draw the ladder on to it, make the bit between the rungs completely transparent and voila, one ladder). For windows however it's nice to have that glass effect, semi transparency. This is what we've got here, and you get it by converting without the -trans option.

Let's get the Alpha Channel displayed so we can actually see what this mask looks like. Click on Masks and then click on Load From Alpha Channel. It's called 'Alpha Channel 1' so select it and click OK - note how suddenly some gridwork has appeared all over the place - and more importantly, in our coaches in the wrong places.

Where you can see grid work is where transparency will happen. The more clearly you can see the gridwork, the more transparent it is. If you are making things with the -trans option for complete transparency, you must make all of your transparent bits completely transparent (you'll find out how in a moment) or else the converter treats them as completely opaque.

Before we edit it, put 'View Mask' on (it's in the Masks menu) as this makes it clearer to see where the mask is.

Now select 'Edit Mask' from the Masks menu and your colour palette will change to greyscale. This is basically because you're now painting the transparency.

Just choose your colour (remember you can always use the dropper to get whatever colour is there at the moment, and while you're in 'Edit Mask' mode the dropper will read the transparency layer not the colours of the main texture itself) and start painting away until you've tidied up the texture.

Once you've finished painting up the transparencies you get something like this:

Before you do your final save, you have to save the Alpha Channel back out so click Masks and then Save To Alpha Channel. Delete the existing 'Alpha Channel 1' and click OK to save yours - when it asks you for the name type 'Alpha Channel 1' in again. The reason for this is because MSTS will only look for the first alpha layer for its transparencies, removing the original one will ensure that yours is the only one there and hence the one that it will use.

Time to convert it again, remember we're not using the -trans option, and see what happens in the sim this time...

As you can see, all the windows are now completely transparent. This also allows you to see that the coach we've used wasn't the right one - we've used the Restaurant Car and ofcourse this has nothing in the middle of the interior so it looks a bit odd. Still, it's proven the point about transparencies nicely.

Starting From Fresh

If you are doing your own loco, or otherwise adding transparency where there wasn't any before, you'll need to create your own Alpha layer. This is very easy, just click 'Masks', followed by 'New', and then 'Show All'. This will create a mask that by default has nothing transparent in it. Now go in to Edit Mask mode and edit away, just don't forget to 'Save to Alpha Channel' before you save - and always save textures containing transparencies as a TGA (Targa) file as BMP files do not support this (atleast not in MSTS).

That's it for transparencies, in the final section we're going to look at just a few tricks in PSP that might help you along the way...