The newer Class 47 (Welsh Marches and Virgin DLC) is very nice, but suffers from no cab occlusion, so the sounds inside are just as loud as outside, and rather distracting. How do you add cab occlusion to it please? The Class 58 has an unconvincing attempt at glazing tinting that has a strange effect of reducing contrast when you look through it from the inside out. How can the effect be removed please?
Pretty easy. Create a Cab Occlusion blueprint and make sure to link to it in the engine.xml. Good occlusion values are -2400, 0.35, 0.5, 1. (The second value has the biggest impact on engine sounds, the higher it is, the more high frequencies are cut off.) 58: Edit the cab glass texture and darken the alpha channel.
Can you recommend a YouTube video that shows how to do this please, or could I copy another model's blueprint and modify it?
Not aware of any videos. Two ways, using the BlueprintEditor or use an existing cab occlusion bin. Then, make sure it is referred to in the engine blueprint (section above the ControlValues) Note that for carriages the occlusion must be linked twice (bottom of screenshot) to work. Even DTG forgot that on many carriages like Mk1 FK or some Dosto coaches.