1 Glass
This material requires a monochrome texture with an alpha channel. Since it is monochrome, an extremely low resolution is sufficient, e.g. 4 x 4. You could also take 1x1, but this is quite impractical in a graphics program at the latest! 
The color channel represents the "color" of the window and is usually grey. Important: You can NOT make a "real" colored window with this! So don't be surprised that you won't get very far with this material type if you choose another color instead of grey.
The alpha channel represents the transparency. For the glass above I used a dark grey (76, 76, 76, 76, equals 30%).
What you can't see here is that the glass has a clear white light reflection when using the "post-rendering effects" (not yet implemented). In "conventional" mode, however, the light reflection is unfortunately almost not visible.
As reflection texture I chose "sharp_envir.bmp", because the reflection of the environment in the window glass appears sharp - in contrast to painted metal.
Here now the properties:
By the way: At the moment this material does not work well with the snow algorithm. Therefore you may not set a snow texture.
2 DL / ND313
2.1 Outside without windows
The outer skin of the DL uses the alpha channel of the main texture for the gloss level, therefore the (transparent) windows are not included here, but the blind windows are present. The special features are:
- material type "Complex with normal map" (logical )
- Gloss factor = 2, this makes the blind windows shiny. In return, the alpha channel of the metal areas must be darkened accordingly.
- Intensity of normal texture = 0.1 - the background is that the metal should be only very slightly wavy anyway. However, since the color depth of the normal texture is limited, unsightly effects will occur if the "lightness" of the waves is only achieved by incorporating only small variations into the normal map. To a certain extent, this results in "staircase effects". It is therefore better to design the waves quite strongly and then lower the value here.
- Glare factor of the reflection texture = 0.2 - The car should shine in the sun, but the reflection texture should not be too strong
- Silk matt characteristic: Uses the spectrum of the alpha texture better... well, is somehow easier to handle.
- Oblique view reduces transparency: Typical effect of windowpanes and lets the blind windows look better
- Normal Texture and Normal Texture are assigned, of course. The alpha channel for the dummy windows is white, that of the metal is 64.
- Reflection texture = "sharp_envir": For the SDs we used the former pendant to "smooth_envir" here, but the paint was not that nice. Nowadays the cars shine a bit more, so "sharp" fits better
2.2 Windows from outside
A distinction is made between windows from outside and inside. Seen from the outside, the windows should be a little less transparent, so that you can perceive them well as part of the vehicle, but from the inside, they have a significant influence on the view and should therefore be very well transparent. The special features are:
- Material type "Complex with normal map": The windows should not reflect perfectly, but have a slight "cushion distortion". Therefore the normal map of the car body is used here as well.
- Glare mode Alpha-Transparency: Logical, windows should be transparent.
- Brightness of the gloss point = 5: Due to the strong transparency, the gloss point is also proportionally weakened. To compensate for this, the value is increased here
- Intensity of normal texture = 0.15, for the same reason as for the outer skin
- Factor over alpha channel = 0.4: The actual texture has a rather bright alpha channel. This value can be used to fine-tune it in the ContentTool until you have the perfect result.
- Slanted view reduces transparency: Typical effect of window panes. The more you look through the panes at a slant, the more they reflect.
- Normal Texture and Normal Texture are of course assigned. The color of the windows is gray (127/127/127), the alpha channel is 166.
- Reflection texture = "sharp_envir": Window panes are (almost) perfect mirrors, so the sharp reflection texture is reflected
Window oblique view: Vertical view:
2.3 Grained plastic surfaces
A typical material used in modern buses are single-colored, grained plastic parts. They do not have a texture in the true sense of the word, since they are unicolored. Here the ambient occlusion (i.e. soft shades) and the fine grain dominate:
In DL I created such parts, e.g. the plastic surface behind the windshield, with the following strategy:
- All surfaces to be provided with this material are first combined to one object, even if parts of it are to be animated later! A later separation is no problem.
- Create a monochrome basic texture with very little noise (in our example: ND313_I6.bmp). You can also use different colors, but the basic texture has to be colored accordingly after mapping. But for now we just leave it alone ;-). In addition, we will create a tileable normal map in high resolution (in our example: Narben_1-3_normal.bmp). Both textures can be used multiple times for different materials.
- A Blender mapping function is used to calculate an even mapping distributed over the entire texture, where each part has its own area on the texture and all parts are mapped with the same resolution:
- Edit mode, Face mode and select all
- Assign basic texture
- Press [U] for Mapping and select "Smart UV Project"
- For "Island Margin" enter the value 0.01, the rest can remain
The whole thing looks like this in Blender in the UV editor:
- For the AO, an empty, single-color texture is now created, whose resolution is suitable for the AO (in our case: ND313_I6_AO.bmp). You have to try this a bit, but the resolution does not have to be the same as the (in this case grey) basic texture. In our case I chose blue.
- This is assigned to the object and then the AO is baked (how this works is a bit beyond the scope here...). This texture must be saved in Blender in the UV-Tool!
- However, the object is then exported again with the previously created (in this case gray) basic texture
- After the import, the tangent information must be added and the ContentTool must be restarted after saving.
The material properties must then look like this:
The cruical settings are here:
- Material type: "Complex with normal map", of course, we want to use a normal map as well
- Gloss Factor = 0.3 and Gloss Point Brightness = 1.5: here you simply have to try values with which the plastic will look correct. There is no rule of thumb for this.
- Intensity of the AO texture = 1.0: If the AO is too drastic for you, then a lower value can be taken here.
- Intensity of the normal texture: Here you can adjust the intensity of the normal texture so that the normal map works well and is neither too strong nor too weak.
- Size factor of the normal texture = 5.0: Very important! We have chosen the mapping so that all elements fit on the texture. But this means that the resolution is relatively low. This does not matter for the basic texture, it is monochrome anyway and has no distinct details. The normal texture on the other hand should have a nice high resolution. With this factor you can make sure that the normal texture is internally mapped reduced by a factor of 5.
- Activate "AO texture" on
- "Silk matt characteristic": Just fits well here. But this is not mandatory, you can get the same results by using different values for gloss factor and gloss point brightness
- "AO uses the original mapping": Very important! In the usual cases separate (secondary) mapping coordinates are used for AO mapping. But in this case this is not necessary at all, because we have already chosen the mapping of the basic texture accordingly.
- In the "Textures" section, the corresponding prepared or generated textures are of course selected appropriately.
With sun:
At 100% ambient light (lighting comes only by AO):
