Dev Diary Pt. 24 - Physics / Data / Materials | Ingame Refinement BMW/Alpina 8 series (AC)

peterschroeter (61)in #blog • 6 years ago (edited)

Yummy!

Now that the car is set up in the editor and driveable modeling and physics work can continue. First up modeling the lights beginning with the light strip. Was fortunate enough to find some spare parts pictures to get the signal and reflector bit right...

Lower Lightstrip

From this:

To this:

There's some considerable detail here which will be visible only on close ups but hey...

On to the pop ups and rear lights. These headlight units have 6 materials (headlight glas, blinker glas, chrome, black plastic, bulbs and reflector unit).

Also the 8 series was the only car on sale at the time and still to this day one of the few ones that had 8 fully powered 55W bulbs with low- and high-beams on.

Pop-up Headlights

And the pop ups...

As above with the lightstrip the silver front covers are actually the headlight lense plexiglas parts which in this view are opaque but will later through the right material become transparent.

I still need to work on the geometry and mesh density around the pop up headlight cut outs on the hood, they do throw some ugly reflections ingame.

It'll take a while before it looks like this in game, mainly due to a lack of light sources currently.

But for now this is the result of this work as visible in the editor:

Fixing the Normals

Since I had some inconsistencies with the wheels and some other parts what you do is select all in Blender by pressing 'A' and then 'Ctrl N' which normalizes all vertices. So far so good. The thing is this action flips some faces (in my case wheels and tires plus some little items). You want to activate 'Backface Culling' in Blender's view options so as to display only the front side of the faces. This will show you any parts which are flipped and shouldn't be. Like the rear wheel here:

Simply select those in object mode and hit 'Ctrl-f' which brings up the face manipulation menu and then select 'flip normals'.

It is good practice at the end of this exercise to once again select all and normalize. Then do a final check with backface culling. Any work you do at this stage will be one more export exercise saved down the road.

From here on out remember the Blender .fbx export bug so set your values.

So for correct orientation and scale, with Blender scale set to metric/meters, export usingscaling FBXALL set to .001 and -Z forward. Guess Blender has changed the FBX exporter settings somewhere down the road.

There are the axis directions in Blender's global space which are directly translate to the editor and then the game without them the car won't work, drive and its wheels will not be recognized

Check again and you'll see the axis:

Test Drive

Having reassigned most materials and textures in my test format it was time to set up the data so the physics can start to more or less accurately simulate the big bad 8.

All drivetrain, transmission, engine, car and setup data was complete - work on the suspension continues to this day. The B12 5.7 apparently has a 1st gear ratio of 4.25!! Max speed in 1st: 60km/h.

Look it's the pink panther :). There's an incorrect texture in the headlight strip but at least all lights are visible now but still no glossy, reflective plexiglas. Will get to that later.

It tends to break lose under heavy breaking and also oversteers heavily, on the brightside the countersteer is very effective.

All of that is sort of irrelevant as I haven't put in the actual numbers yet but for now it feels planted, heavy and pulls well. Also isn't too twitchy but very floaty due to my Mercedes like spring and damping ratios.

Also note in the pic above the right exhaust, the inside of the rear fascia needs geometry as I just modelled the painted exterior bodywork - oops. That's ingame backface culling :).

This is what it looked like rendered in the showroom at this point:

For this session I obviously removed the side windows and also have non transparent front and rear windows but hey - the driver can enjoy the pillarless design of the roofline.

Physics and Data

Another test at Circuit Paul Ricard, this time with pop ups closed, some more refined materials and further refined data:

Notice anything? Yes, the windows are transparent.

Lesson learned: AC's engine basically works with two models - one interior and one exterior. For the engine though there are all in one. So the exterior model has windows which face outward and are assigned a transparent material and the interior has a set of windows which face inward and are assigned a special interior (less reflective) transparent material.

I then spent a Sunday in these files:

That was and still is a 90% completion of all the data for this car only lacking the exact pickup points of the suspension arms but more on that later.

Testing resumed at Tsukuba:

Added era specific tires with correct wheel and tire size:

That is done with a very useful feature of oft mentioned Content Manager.

Tsukuba testing impressions:

Random Model Work

This is some camera editing to find the right angles that enable good view without intersecting with any piece of the geometry during fast load changes etc.

All windows transparent inside out and more reflective on the outside...

This also shows AC's ingame suspension tester. Again, for now the suspension is set up simplistically sort of along the lines of the E34 M5 - only difference being the E31 8 series has 5 control arms in the rear.

The thing with the multilink rear axle

As mentioned before this is a very complex suspension type to model in AC and I'll get into that in the next part. Also you will have noticed in some shots that there is extreme subdivision going on resulting in rounded edges which should 'edgy'. I'll also get into that and then the pre-final testing of the suspension on the Nurburgring: