Texture sheet & window question

[vline45]

Hi, just working on another Australian loco (our version of an SD40-2 I think it has been called) to hopefully release, a Victorian C Class, but a couple of questions.

loc1.jpg tex_sheet1.jpg
1. I have arranged all loco textures onto a 4096x4096 sheet, is something like the above sheet good practice for enough detail (especially when editing paint to look realistic)?
2. On the note of texture editing, my basic go to method to in Gimp is going Filter -> Noise -> RGB or HSV noise, that adds a different speckled effect of darker and lighter pigments, is there a better way?
3. As shown in the Blender side parts list, I have the windows set as a different part named "windows.outer" under a collection named AlphaNorm. Is this correct? I think I just set it that way looking at a sample locomotive somewhere. Should the windows be on a separate smaller texture sheet?

Thanks.

[superheatedsteam]

1. Having less textures per model is good practice as it reduces draw calls at runtime. A larger texture uses more video card memory but this is not so much of a problem with modern video cards. Running unit trains in a desert route uses less video memory than mixed freight in high density urban routes. My loco models now use one or two 4K textures for the external model depending on how much detail I have added. Even at 4K sometimes you get 'jaggies' when you look close but not as pronounced as 1K or 2K.

2. I have used this technique just recently for the hull colour of a ship model I am working on. I made a copy of the layer of saturated colour I used for the hull. On that copy, I used RGB noise filter on it and adjusted the colours so it was a close match to the underlying saturated colour. I then applied Filter > Blur > Linear Motion Blur to the copied layer and changed the angle so the blur was in the vertical direction to change the speckles to streaks. I then play around with the modes so that the blur layer is blended with the underlying saturated colour layer to get the effect I want. Be aware that some of the modes 'smear' the blur beyond the underlying colour boundries so more editing or masking may be required. I sometimes also play with the Opacity of the layer if the effect is to strong.

Depending on the effect I want, I also use rendered Difference Clouds.

I create a new layer on top and fill it with white. Then use Filters > Noise > Difference Clouds. Adjust values as desired. Adjust the opacity of that layer to around 1-5% to break up the saturated colours. I then either cut out the areas I don't want this effect on, but to be more efficient and have a non destructive work flow I should really use masks.

In short there are a number of different ways to break up saturated colours.

3. For transparency you don't have to put the windows object it in separate collection. For an object to have alpha channel enabled in the texture, make sure the Transparency is set to Alpha Blended (for 8-bit alpha) or Transparency On/Off (fro 1-bit alpha) in the MSTS Materials section of Material tab in Blender.

alphaBlended.jpg

[vline45]

Ok cool, thanks for the assistance. I've only ever used one texture for a loco, so if I have two or more textures for a loco, in the MSTS Materials --> BaseColorFilepath, I can select all texture files there at once, then export?

I'll play around with those texturing techniques in GIMP and see what eventuates, this is the first loco I pretty much totally painted and liveried within Blender in solid colours, exporting the PNG between GIMP and Blender to alter, but as I understand it, the Blender painting tools are pretty primitive, but they seem to do the job for the base coat.

Alright so the faces used for windows can be removed from the separate AlphaNorm collection and be joined to the body mesh object. If using Alpha Blended, does this allow grey scale to be used to control transparency e.g dirt around the outer area of windscreen wipers? (I saw this on an early MSTS loco and it looked quite good). In my UV Editor shown below, I have the front windshield glass positioned within the cab windows, do I just fill these faces with greys to control the amount of transparency?
c_wndw_uv.jpg

Thanks for the hints and tips!

[superheatedsteam]

1. Yes but before you do that you need to make a new material. Click on the New Material button which basically makes a copy of your existing material and puts a .001 at the end of the material name. Rename that material to what ever you want. Then with the new material selected, go and change the BaseColorFilePath in the MSTS Materials section for the other texture file you want to use. So now you have 2 materials, each one points to a different texture file.

blenderNewMaterial.jpg

It you want to apply that new material to another object, select the 3D object and click the Browse Material To Be Linked drop down and select the new material from the drop down list. That material will now be applied to that object.

I my dropdown in the screen shot below you will a number of materials that are part of this project but only 4 materials (in this case '4 textures') are actually applied to the different parts of the model that are exported. Learning how all this fits together took me the longest time but it slowly sunk in by watching many tutorials on youtube.

blenderBrowseMaterial2bLinked.jpg

In short you want a material for each texture you apply to the model.

2. Actually blender can assist in creating textures that range from primitive to photo-realistic. I would suggest staying with what you are doing on this project and will will ground the you in the fundamentals. If you wish to migrate later towards photo-realistic the you have to learn PBR and materials in blender beyond just representing just a single texture file. At that point you are looking at .glTF shape format export, not .S. A whole new can of worms.

3. For the Window transparency create a layer of grey colour where the windows are mapped to on the texture file. In the screen shot below I used a randomised dust colour, but I have also used a layer of blue with a render of Difference clouds on it to make the window look like it is reflecting a blue cloudy sky.

Then change the opacity of that layer in GIMP to around 3-9% as you see fit. Also in the screen shot below I have erased all colour where the wiper sweeps, so the dust or blue clouds layer will be translucent and the wiper sweep transparent.

gimp_8-bitAlpha.jpg
In short it is the opacity of the layer in GIMP that controls the level of translucency (via grey scale) in the alpha channel on export to a file format that supports alpha channel.

Hope this helps.

[vline45]

Immensely helpful, clears up a few issues for me. Thanks very much.