Object that slides downhill

I'm trying to make a bobsled object that slides down a hill with almost no friction, but trial-and-error is very frustrating.

I have exprimented with the vehicle paramaters and cannot seem to get what I want.

I've tried giving it a push, it just seems like there is too much friction no matter what settings I use (unless the hill is EXTREMELY steep.) I am trying to make something that will slide down even a gentle slope.

Also, is there a way to make the vertical attractor work in relative to the grade of the ground instead of absolute rotations?

Any hints greatly appreciated!

Buster

default
{

    state_entry()
    {
        llSitTarget(<0, 0.03, 1>, ZERO_ROTATION);
        llSetCameraEyeOffset(<-5.0, 0.00, 2.0>);
        llSetCameraAtOffset(<3.0, 0.0, 2.0>);
        llSetVehicleType(VEHICLE_TYPE_SLED);
    }

    changed(integer change)
    {
        if (change & CHANGED_LINK)
        {
            key agent = llAvatarOnSitTarget();
            if( agent) 
            {
                if (agent != llGetOwner())
                {
                    llUnSit(agent);
                }
                else
                {
                    llSetStatus(STATUS_PHYSICS, TRUE);
                }
            } 
            else
            {
                llSetStatus(STATUS_PHYSICS, FALSE);
            }
        }
    }
}

There are several things you can do, ranging from tampering with llSetForce to creating an absolute movement and rotation using llGroundSlope, llLookAt, and if necessary, llMoveToTarget.

For example, to get a system of rotation going, try:

llLookAt(llGetPos() + llGroundSlope(ZERO_VECTOR),0.3,0.3);

Any idea how I can get it to slide?

Here's something to get you started, untested:

vector slope = llGroundSlope(ZERO_VECTOR); // Our Slope
vector position = <0,0,0>: // So we don't need to redeclare it each time
float SPEED_CONSTANT = 20; // Our Speed Modifier
float HOVER_HEIGHT = 0.5; // Height above the ground you want object to be

while(slope.z > 0.1) 
{
    llLookAt(llGetPos() + llGroundSlope(ZERO_VECTOR),0.1,0.1);
    llSleep(0.12);
    slope = llGroundSlope(ZERO_VECTOR);
    position = llGetPos() + (SPEED_CONSTANT * slope.z * llGroundSlope(ZERO_VECTOR));
    position.z = llGround(position - llGetPos()) + HOVER_HEIGHT;
    llMoveToTarget(position,0.3);
}

After some quick testing, here's a revision of the (simple) code that still runs a little fast:

default
{
    state_entry()
    {
    }

    touch_start(integer total_number)
    {
        vector slope = llGroundSlope(ZERO_VECTOR); // Our Slope
        vector position = <0,0,0>; // So we don't need to redeclare it each time
        float SPEED_CONSTANT = 200; // Our Speed Modifier
        float HOVER_HEIGHT = 0.7; // Height above the ground you want object to be
         
        while(llAbs((integer)(slope.z * 100)) > 0.1) 
        {
            llLookAt(llGetPos() + llGroundSlope(ZERO_VECTOR),0.1,0.1);
            llSleep(0.12);
            slope = llGroundSlope(ZERO_VECTOR);
            position = llGetPos() + (SPEED_CONSTANT * slope.z * llGroundSlope(ZERO_VECTOR));
            position.z = llGround(position - llGetPos()) + HOVER_HEIGHT;
            llMoveToTarget(position,0.3);
        }
    }
}

This may well have no relevance at all, but what material is the object made of? If memory serves I read that glass has the least friction.

I did switch to glass and that didn't make a difference

Hmmm -- that's sort of cheating. I was hoping to come up with a way for a physical object to slide. I've been having fun rolling balls down my hill, but I really want to make a sled that slides down. I didn't try this script yet, but I will shortly.


THANKS a million for you help!

Jeffrey,

I tried it and it did orient the thing exactly right, but it doesn't move. After I got out of world I looked at the script a bit more carefully, and I suspect it has to be physical? I will try that next time.

Its always a good day when I learn something new!

Buster

Yep! I was too lazy to add llSetStatus(STATUS_PHYSICS,TRUE);