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Issue Details (XML | Word | Printable)

Key: SVC-1975
Type: Bug Bug
Status: Resolved Resolved
Resolution: Fixed
Priority: Major Major
Assignee: Andrew Linden
Reporter: WarKirby Magojiro
Votes: 41
Watchers: 8
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2. Second Life Service - SVC

Havok 4: Avatar jump height is greatly lessened

Created: 02/Apr/08 01:31 AM   Updated: 19/May/08 09:21 AM
Component/s: Physics
Affects Version/s: Havok4 Beta, 1.20.0 Server
Fix Version/s: 1.21.0 Server

Issue Links:
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Linden Lab Issue ID: DEV-13613


 Description  « Hide
Under havok 4, the height the avatar can jump to is massively decreased. For reference, by jump, I mean tapping the e or PGUP key without holding it down.

This is a problem, as it breaks a lot of content. The Jump animation in my AO, fdor instance, is designed arounmd the avatar jump height, so that I spin gracefully in the air and land on my feet. Under H4, I hit the ground mid-spn.

This also causes problems for any area which uses jumping. Obstacle courses, and such. Which are based around the avatar's capabilities and adjusted to match.

Please fix this soon.

Edit: statistics.

I used the script detailed below to obtain these results.

Havok 4:
[8:16] Object: Jump height was: 2.803389
[8:16] Object: Jump height was: 2.813299
[8:17] Object: Jump height was: 2.804680

approximately 2.8 metres.

havok 1:

[8:20] Object: Jump height was: 3.964437
[8:20] Object: Jump height was: 3.969215
[8:20] Object: Jump height was: 3.969231

approximately 3.96

A loss of over 1 metre in jump height.



//-------------------------------------------------------------------
vector x;
float starting_height;
float highest_height;
float current_height;
integer started;

default
{
    state_entry()
    {
        llRequestPermissions(llGetOwner(), PERMISSION_TAKE_CONTROLS);
        llTakeControls(CONTROL_UP, 1, 1);
    }

    control(key id, integer level, integer edge)
    {
        if (started == 0)
        {
            x = llGetPos();
            starting_height = x.z;
            llSetTimerEvent(0.05);
            llResetTime();
            highest_height = 0.0;
            started = 1;
        }
    }
    
    timer()
    {
        x = llGetPos();
        current_height = x.z;
        if (current_height > highest_height)
        {
            highest_height = current_height;
        }
        
        if (llGetTime() > 5.0)
        {
            llSetTimerEvent(0.0);
            started = 0;
            llSay(0, "Jump height was: "+(string)(highest_height - starting_height));
        }
    }
}


 All   Comments   Change History      Sort Order: Ascending order - Click to sort in descending order
WarKirby Magojiro - 02/Apr/08 01:33 AM
Jira had some problems white I was making this, and there may be more than one copy of it as a result. If so, consider this the master one, and close others.

Alexa Linden - 07/Apr/08 02:42 PM
Can you provide us with Comparative metrics for this? are you noticing this difference without your AO on?

RobbyRacoon Olmstead - 07/Apr/08 03:24 PM
Ummm... I don't have any numbers from before, and no longer have access to a Havok 1 sim to generate them, but I can tell you that strong anecdotal evidence from hundreds of users will back this up.

Aimee Congrejo - 07/Apr/08 06:15 PM
Yah, you definitely can't jump as high in Havok4 as you could previously. A perfect example is the structure on my land. It's a concrete bunker that's about 4.6m tall. I *used* to be able to jump on top of it. Now I can't. I just made a 3.25m tall prim next to the 4.6m tall bunker and I *can* jump 3.25m. Any higher and I can't jump on top of it.

Chilli Cao - 08/Apr/08 08:06 AM - edited
yes i can double that Aimee - jump is near 1.5meters shorter than it was.
i can confirm numbers later if needed
also the AO is irrelevant to how high we jump as it only animates, so same effect with or without AO.

it used to be possible to jump exactly ontop of someone else's head and stay there (if you were good/lucky enough).
On havok4, not only its more difficult to jump that high/long (avg height human avatar), as you need to be closer,
but you slide off their head as well

not fun! :o)
showstopper! :o)


WarKirby Magojiro - 08/Apr/08 08:21 AM - edited
Added numbers to the description. we've lost over 1 metre in jump height.

The difference is definitely noticeable without, and has nothing to do with; my AO.

The script works by repeatedly checking the avatar's zpos in a tight timer loop, and recording the highest obtained value as the jump height.

Havok 1 sims are on the beta grid in case anyone's wondering.

Eyana Yohkoh - 08/Apr/08 08:43 AM
There is definitely a noticeable and drastic difference. We were testing a jumping training course and it was nearly impossible now because of the change.

RobbyRacoon Olmstead - 08/Apr/08 08:49 AM
Ah, nice point, WarKirby, I hadn't thought of that.

But.... How can it possibly be the case that LL wasn't aware of this and needs comparative metrics from residents?

travisd kanto - 08/Apr/08 09:21 AM
Aye, I've definitely noticed this difference, really wish it was fixed to what it was previously.

Zero Gee - 08/Apr/08 10:02 AM
Don't have any numbers myself as I don't go on the beta grid much, but I know they're available. I know there is a difference, anyone with two cents who has used the csi system before and after can see it..

Deejay Kamachi - 08/Apr/08 10:23 AM
I am in agreement that this change has a major impact on AO developers and entire systems within Second Life such as the Combat Samurai Island system. I will look at the beta grid later to try and record some sort of metrics.

Solace Obviate - 09/Apr/08 05:54 PM
I too agree that the jump height has been significantly affected by H4. In fact this was one of the main reasons did no frquent the H4 tester sims for a long time in hopes of LL addressing such issues before the official roll-out.

Jenrose Meredith - 10/Apr/08 03:46 AM
I use the kifuraito hud to do multiple jumps at once, and I swear it is going to give me carpal tunnel because I have to hit the key more often to get to the height I want (and the kif is more controllable than flight in a lot of ways). My whole movement style is based on jumping, this is driving me crazy. I may have to resort to multiple jump assists to get the effect I want now.

Eyana Yohkoh - 16/Apr/08 02:19 PM
Applying a non-local push with the force somewhere between <0, 0, 5.5> and <0, 0, 6.0> during a jump (from standing still) multiplied by the person's mass achieves approximately the old jump height. This is difficult to judge because the only way to measure that I know of is by using a fast timer.

This is inconsistent at best and if the agent is running then the same push might send them up to over five meters per jump, or might only give them a half a meter boost, or anywhere in between.

Andrew Linden - 17/Apr/08 08:39 AM
The simple formula for peak height of a projectile in uniform gravity is:

h = (Vo)^2 / (2 * gravity)

Where Vo = initial velocity

Solving for Vo we get:

Vo = sqrt( 2 * gravity * h)

The ratio of Vo1 by Vo4 is:

Vo1 / Vo4 = sqrt( h1 / h4 )

Solving for Vo1 we get:

Vo1 = Vo4 * sqrt( h1 / h4)

Puting in the numbers:

Vo1 = Vo4 * sqrt( 3.967 / 2.80 ) = Vo4 * 1.19

So, the impulse velocity of jump needs to be increased by a factor of about 1.19.

Zero Gee - 17/Apr/08 04:51 PM
Oh, hes good... hes real good. How come he didn't get assigned to our kick/push issue as well?

Malachi Rothschild - 17/Apr/08 04:58 PM
You mean this kick/push issue?

http://jira.secondlife.com/browse/SVC-1648


Zero Gee - 17/Apr/08 05:00 PM
Why ues, that kickpush issue. ^_~

RobbyRacoon Olmstead - 17/Apr/08 05:58 PM - edited
I am extremely pleased to see that work is being done on the avatar jump issue, as it affects so many people, but I agree that I'd be even more ecstatic to see work being done on the kick/push issue as well :)

In the meantime, thank you Andrew Linden for that analysis, it might help me with coming up with a short-term workaround for some Combat: Samurai Island issues that were created by Havok 4

.


Andrew Linden - 17/Apr/08 06:18 PM
I scaled the avatar jump impulse by the value above and it worked perfectly. However, the fix won't be deployed until next week at the earliest.

RobbyRacoon Olmstead - 17/Apr/08 06:39 PM - edited
That's awesome, thank you!

Andrew Linden - 19/May/08 09:21 AM
The fix was deployed a few weeks ago.