Hi Marco,

I am changing your car tutorial to multiplayer example and i have some questions.

1. My car is smaller than your's and it is not working good as yours. Which variables, constants i have to change if i scaled your car ?
/ My scale is 20cm=1quant /

2. In multiplayer mode, i have created 2 physics car. And it is working good on server, but on client it does not accept key controls.


Thanks, Olzii

Thanks Marco,

I have another questions :

- Is there another method to lift up car without creating hook (like u) ?
Because while i am changing it to multiplayer i have to declare many
pointers for each car.
(in Newton physics it can be done changing chasis position higher and reset
the car transformation matrix)
- Is it better or worse to make all my AI-car to physics car in my car game ?
Can engine handle it if i use more than 20 physics car and some physics
objects ? /I own 6.31.4 PRO edition/

Olzii

that would be 100 physic-objects, from my testings that wont work good (if its not a very fast pc)
i once tried to built a house out of physic-objects (single stones), but specially at startup it was slower then a slideshow. so i think you should test it and see what happens.

you could try to let the ai-cars only have physics enabled when near to the camera, wouldnt that work?

Where can I find the tutorial?

Wildcard

I currently have 8 A.I vehicles using the physics engine. In total that's 4 wheels x 8 and 1 chassis x 8, which equals 40 active physics objects. This runs at 80 - 90 FPS with just one vehicle and the environment in view(remember all the other karts are racing). My computer has 2GB of ram with 3.0ghz and a Radeon 9800 graphics card. Of course there is thousands of lines of code running on top of this so I cannot give you an estimate of what it would be like with just the barebone vehicles racing(quite a bit better I'd imagine).
Anyways, all i'm saying is its possible to have at least 8 racers. If your going commercial then give the option for 4, 6, or 8 racers in your grand-prix mode and all should be good. Personally, I like racing against 6 vehicles. Also, the framerate increases to 120-130FPS.
Ello has a good idea, but if your using pretty closed circuts(and the vehicles you see vary quickly) theres a possibility for huge slowdown with all the enabling/disabling code. Also, it wouldn't help the playing experience if you seen the A.I kart land a jump like it's floating on air(considering your timing is off for enabling them back in the physics engine).

Watch these variables:

PH_FPS_MAX_LOCK = 70;
PH_CHECK_DISTANCE = 20;
ph_setautodisable(100,100,100,100); // turn off
time_smooth=0;//dont set at "1", bug with physics engine

They make a huge difference on your performance. PH_FPS_MAX_LOCK when set higher can slow things down alot with multiple vehicles. When PH_CHECK_DISTANCE is lower it will slow down the performance. Do some testing, see what works for you in the balance of performance/stability. I'd reccomend giving the user an option to change the simulation of the physics in the end as well(for higher end users).

P.S - Incase anyone wants to know for the future. I've found a great way to do spinouts(like in Mario Kart) and whatever else you'd like. Just make your real physics vehicle invisible, reduce it's speed accordingly, then create another model and have it do what you want(while following your invisble vehicle). I know this seems like common sense, but I spent an uneeded amount of time wrestling with the physics engine trying to do spinouts and flip effects. It's quite hard to make something in the physics engine do the same thing each time(if not impossible) for an arcade racers spinouts.

About the flipping - Heres some code I made up:

Code:

---

//Put this on the top of your function
var stop_vanish2;

/*Put this in a while loop, be sure to change the pointer from "kart1" to whatever your main chassis's pointer is, the same goes for the wheels of that chassis/*
.
  if(!key_x && !joy_4 || !joy_4 && !key_x) && (kart1 == me){stop_vanish2 = 0;}
  if(key_x && !joy_4 || joy_4 && !key_x) && (kart1 == me) && (stop_vanish2 == 0)
  {
   stop_vanish2 = 1; my.lightrange = 0; 
   vec_set(temp.x, my.x); temp.z += 30;
   phent_enable (kart1_FL,0); phent_enable (kart1_FR,0); phent_enable (kart1_RL,0); phent_enable (kart1_RR,0); phent_enable (my,0);
   vec_set(my.x, temp.x); vec_set(kart1_FL.x, temp.x); vec_set(kart1_FR.x, temp.x); vec_set(kart1_RL.x, temp.x); vec_set(kart1_RR.x, temp.x);
   my.tilt += 180; kart1_FL.tilt += 180; kart1_FR.tilt += 180; kart1_RL.tilt += 180; kart1_RR.tilt += 180;
   my.pan += 180; kart1_FL.pan += 180; kart1_FR.pan += 180; kart1_RL.pan += 180; kart1_RR.pan += 180;
   phent_enable (kart1_FL,1); phent_enable (kart1_FR,1); phent_enable (kart1_RL,1); phent_enable (kart1_RR,1); phent_enable (my,1);
  }  

---

What it does is temporarly un-enables your vehicle from the physics engine, then flips it using basic pan/tilt/roll and then re-enables it.

BTW - sorry about the double post, I missed this question in the first one...

Thanks, William

I'll try your flip code.

Olzii

Hi Marco,

I have two question.

1. I said you before my level has scaled /1quant=20cm/.
I couldnot find any information about your car tutorial level's scale.
In Update_speed() function there is one line :
linSpeed= vec_length(vecLin) * 0.091; // convert from quant/sec to kmh
How many meters or centimeters are equal to your level's one quant ?
2. I want to make manual gear transmission for my car. Please give me some
advise how to do it ? Is there any tutorial about gear shifting ?

Olzii

The usual assumption is that 1 quant= 1 inch= 2.54 cm

In the car demo there's a linear relationship between how much gas you apply and the velocity that you get. I also added a maximum velocity that can not be exceeded. For a manual transmission you would have to implement a maximum velocity for each gear. E.g. the second gear only allows velocities up to 30 kmh. Of course it also affects the amount of wheel torque available for accelerating. In the demo this wheel torque is a constant and you would have to adjust the script to take into account what gear you are in (low gear= high torque, high gear=low torque).