Cars Daft question - why do some car mods cause frame rate drops?

[Mekonrider]

I'm currently getting about 90fps in VR using CSP and Sol 2.0 and most bells and whistles fairly high, but I noticed that when I ran a race with Sergio Loro's Modena ST60s in it the frame rate dropped to about 60fps. I swapped back to Kunos only cars and it ran about 90fps again.

I had the same problem with the GPL mod in Rfactor 2 as well, completely destroyed the framerate.

 

[Fat-Alfie]

The ST60 only has a single 3D model, and it uses this high-poly model no matter how far away from the camera the other cars are - the more cars, the more tris AC has to render.

The Kunos cars you talk about have different levels of detail depending on how far away the car is. Up close, it will use the high-poly model, but further away the game shows lower and lower detailed models, needing fewer tris and giving better performance.

 

[Gevatter]

I'd like to add that this question actually isn't daft at all, it's pretty valid in my view.

 

[Mekonrider]

Thanks for the reply. Clears that up anyway! I was just surprised how much of hit some of the cars seem to give the system.

 

[Fat-Alfie]

From the Kunos SDK:

The following triangle-counts are recommended in most cases.
Exterior:
LOD A exterior: 125,000 triangles
LOD B exterior: 20,000-25,000 triangles
LOD C exterior: 10,000-12,000 triangles
LOD D exterior: 2,000-3,000 triangles (as low as possible while you can keep the main shape)

So if you imagine you have 20 cars on screen with no LODs that would be 2,500,000 triangles for the game to render.

But, if they were in the distance and had a full set of LODs, that could be as low as 40,000 tris - quite a big difference.

 

[Billy Pilgrim]

I'm pretty sure I've tried some mod cars that had LODs yet they still give poor FPS.

 

[Ben O'Bro]

I'm pretty sure I've tried some mod cars that had LODs yet they still give poor FPS.

i'll give you the Caterham Academy for that
i did do the LODs, but there's too many separated objects... which is also something to look at

best to look at kunos cars in number of polygons and objects on their lods, they did their job really well

 

[AccAkut]

Worth noting that later Kunos cars don't even follow those guidelines they set themselves. But even just two LOD levels (and low res cockpit, even if its just a delete of a detailed instrument cluster!) can do wonders to a full grid.

Some modders used that "automated LOD tool" someone released a while ago issue with that is that it does not reduce the number of objects.

 

[Stefan Mizzi]

I have the same issue, real pity tbh as there are some great cars out there which I cannot race against AI in VR.

Is there some setting or some software I can use to maybe update these LODs? Or its something only the modder/creator can do?

Cheers

 

[pumpkineater23]

On my PC, the mod cars and Kunos cars hotlap at any track at around 85 - 90 FPS (in VR).
But the Kunos GT3 RS is around 45 FPS for some reason? At first I thought it might be the sound mod, so I tried different sound mods and still the low framerates.