How to build a T3 - Part 3
Step 4: The wheels
Spoked wheela are among the hardest parts to build in Rail3D. To look right, you need a lot of panels, but it is precisely the wheels which have to be animated and demand lots of processing power if they're too complicated.
Essentially, there are three possible approaches:
- Build it from scratch with the cylinder tool, using matrix manipulations to rotate the spokes
- Use Mark Goodspeed's spoked wheel generator spreadsheet
- Cop-out and replace the wheel with a transparent texture on a single panel.
Mark's spreadsheet works very well for big wheels with lots of spokes (which is what it was designed for), but on smaller wheels the results are less convincing. The transparent texture idea is attractive, and often used in MSTS, but is never convincing when seen in close up.
As Mark's spreadsheet is the quick and easy solution, it's always worth trying it first! You can get hold of it via the Rail3D Group. We need a wheel with 11 spokes, diameter 110 cm. In the T3 file, or in a separate file if you prefer, set up a new component:
Name KPEV_T3_11spoke_110D
Component
Metric
[end]
[Tip: don't use the string "wheel" in the name; it can cause problems because it is a Rail3D keyword.]
Now enter the appropriate parameters into Mark's spreadsheet, and paste the result into the stock file. If the pasted data looks messy because of all the tabs, select everything, and do a shift translation, leaving all the parameters set to zero. This reformats the text and gets rid of the tabs.
This isn't bad, but the spokes make it a bit obvious that the wheel is an eleven-sided polygon. You can improve it by making a 22-spoke wheel and deleting half the spokes.
After playing around with the colours a bit, adding a balance weight and putting in the missing hub panels where the spokes were deleted, it looks like this:
The remaining irregularities in the width of the spokes are due to rounding errors - it will look better in future versions of Rail3D. I've cheated a bit by using a small texture with a colour gradient to give the outer face of the spokes a more natural look.
It's a good idea also to add a crank and crank-pin at this stage. Because of the well-tank, we won't need to model the axles, however.
For technical reasons, we need to build a separate, left-handed wheel once the right-handed one is completed. To do this, simply copy the whole wheel component to the end of the file, giving it a new name, e.g. KPEV_T3_11spoke_110D_L.
We need to reflect it in W, and rotate it by 90 degrees around the axle so that the two sides of the engine are in the right phase relationship. We could do this in several different ways: the quickest is a simple matrix transform, which does both operations at once.
This has the side-effect that all the panel normals get reversed (the wheel is "inside out"), so we still need to do a reverse panels and correct the Q-codes.
Next: Getting it moving