Where did I say the grip is constant? I said the grip can be calculated using constant values.
For eg: the grip of the track at a certain point is constant. These values can change over time (the track becomes wet
for example) but for calculating the actual grip at the moment these values can be regarded as constant.
If something is calculated using constant values it itself must surely be constant, right? Can't see any way out of that.
Yeah, and what? These variables do not depend on each other. The grip of the track at a certain point does
not depend on the fuel amount or the tire wear. Neither is depend on the steering angle. These are parameters that modify the calculated grip but does not depend on each other.
Lets say the physics engine runs at 30 ticks/second, and a corner takes 3 seconds to naviage. 90 ticks. For the first 20 ticks I brake, then I turn for the next 70. The braking takes me from V0 to V20. When we turn in our grip is dependant on V20. The grip at tick x is going to dependant on Vx throughout the turn.
Problem: Without simming it I cannot tell you what my velocity, which impacts on my grip, will be at tick 20, nor can I say what it'll be a tick x. It's all dependant on the state at tick 0. Do I know if this is a good line or not? No idea, would have to calcualte based on the initial state. Lets say we do this and it's not. Maybe we'll try something different and brake for 21 ticks before turning. We have exactly the same problem. Don't know if this is faster withing simming. When you look at all the combinations of inputs, especially as many are analogue, suddenly we're getting into "would take longer than the life of the universe" amounts of processing. The amount of combinations of "brake on ticks [a, ..., n], turn on tick [b, ..., m]" that there are is mindboggling enough.
Furthermore this is for one single starting state, a state which might not be the best state to start from. Maybe the perfect line requires me to be 1m to the left. Maybe 40cm. Maybe 19.99909998cm. Perahps I should be going a little faster. Maybe I should have started the braking a couple of simulations ticks ago?
Now if the cars were nice and simple. No aero, no fancy springs, constrained to a 2D plane of the track with a grip that doesn't vary at all around the corner we'd perhaps have a chance at finding the best line, especially for simple single corners. As it is, with the grip at every simulation tick dependant on all the previous ticks? No chance.
The best line is clearly constant. It can be pre-calculated. The AI just has to follow the pre-calculated line. Using this it is trivial to calculate breaking and accelerating points.
Incorrect. Cold tyres, worn tyres, options/primes, amount of water on the track, track temperature, fuel quantity, damage, horsepower, brake wear, whether KERS/DRS are available, fuel mix... these things can only be known as the car is actually going around the track. Even if these we all known see above for why it can't simply be calculated.