Combining building addon parts with bitmap skin manipulations

Recommended for users experienced with working as described in the previous post and also familiar with the PopTop User Skinning Tools included in the free "Coast-to-Coast" addon

We presented previously a methodology to create structural extensions of buildings, such as foundations. We explained under the section "Peculiarities of the RR Tycoon's handling and behaviour of 3DP objects" that "only 1 bitmap skin file can be attached to each Building, namely the one specified at byte address 124 of the BTY file". This unique bitmap skin has to be utilised also for the described extensions of each building. From time to time however, the default building bitmap skin supplied with a building's body may lack textures that we want to include in its extension.

When looking at typical building skins from Railroad Tycoon III, we always observe sizeable empty areas of black colour, which are more often than not unused by the model. These areas can be filled with the texture(s) desired for the proposed extension(s), and then allocated through the extension's 3DP model to the various surfaces of that extension. Let's take for example the "Museum" structure provided with all distributions of Railroad Tycoon III. This skin is to be found in the ...\Data\3D directory of the Railroad Tycoon III installation within the packfile "rt3_DDSF.PK4" under the filename "Museum_A.dds" along with its 5 sister files sequentially designated from "Museum_B.dds" to "Museum_F.dds". Each of these sister files is half-dimension of the previous one (therefore less detailed) and its purpose is reportedly to speed up rendering time of 3D objects when zooming out to a larger area of the field.

As said in the previous article, these PK4 archives can be opened with the Watto Studios Game Extractor.

Using a bitmap painting program, we can fill these black, unused areas with a texture that will be used by the proposed foundations, such as concrete. If we lack appropriate software for processing the dds image group directly, we can convert these to TGA format and work with them (Corel Photo Paint is proved to do the job correctly preserving the object masks), making the building skin like this:

In case we did work with the TGA substitutes for the repaint, it is advisable to reconvert these to DDS in order to save filesize and vastly improve processing speed and framerate. Normally, we would start with the larger "Museum_A" only and then save the image repeatedly down to the "F" size, each time redimensioning it by half. However, we can save ourselves some effort by tricking the User Skinning Tools to do it. More specifically, we can name our modified skin "Museum_Loco.tga" and place it in the "TrainSkin" subdirectory of "UserSkinningTools". We can then run the "TrainSkin.exe" utility, specify the file "Museum_Loco.tga" as an alternative Skin for any of the available locomotives in our Railroad Tycoon III installation, choose a name, say "XYZ", and press "Convert". This way, the utility will automatically create the 6 skin files from "Museum_A.dds" to "Museum_F.dds" and place them within a PK4 package called "XYZ.PK4" inside the "UserExtraContent" subdirectory, as if it were an alternative locomotive skin. We extract the 6 skin files from XYZ.PK4, e.g. with the Watto Game Extractor into "UserExtraContent", then we erase XYZ.PK4, it is of no more use. We will have to rename slightly the 6 skin files, so that they bear the correct "Museum_A.dds" to "Museum_F.dds" names. Now, our modified Museum skin is active in place of the original one, as long as we keep it in "UserExtraContent".

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In order to put our enhanced skin to use, we need to create a 3DP foundation of the Museum structure in a hex-editor. The simplest option, that we will use, is a cube which will read its skin from the repainted area of "Museum_A.dds". As mentioned in the previous post , the exact 3DP file structure is described here

The Museum building with the unsightly void underneath

The Museum after the intervention proposed here

Download here for examination and use the modified skin files and sub-base model. Unzip everything into "UserExtraContent".