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ubODE vs. Bullet

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tringate

ubODE vs. Bullet

I am working on a script for a submarine and am having issues with it working fine in ubode but will not dive or surface in Bullet physics.

Here are the primary items that are involved with the physics.

This is the initial settings the object is set with.

set_engine(){

llSetVehicleType(VEHICLE_TYPE_BOAT);

llSetVehicleFloatParam(VEHICLE_LINEAR_DEFLECTION_TIMESCALE, 0.5);

llSetVehicleFloatParam(VEHICLE_LINEAR_MOTOR_TIMESCALE, 0.1);

llSetVehicleFloatParam(VEHICLE_LINEAR_MOTOR_DECAY_TIMESCALE, 0.1);

llSetVehicleFloatParam(VEHICLE_LINEAR_DEFLECTION_EFFICIENCY, 0.80);

llSetVehicleVectorParam(VEHICLE_LINEAR_FRICTION_TIMESCALE, <1, 1, 1>);

llSetVehicleFloatParam(VEHICLE_ANGULAR_DEFLECTION_EFFICIENCY, 0.2);

llSetVehicleFloatParam(VEHICLE_ANGULAR_DEFLECTION_TIMESCALE, 1.0);

llSetVehicleFloatParam(VEHICLE_ANGULAR_MOTOR_TIMESCALE, 0.5);

llSetVehicleFloatParam(VEHICLE_ANGULAR_MOTOR_DECAY_TIMESCALE, 0.2);

llSetVehicleVectorParam(VEHICLE_ANGULAR_FRICTION_TIMESCALE, <0.1, 0.1, 0.1>);

llSetVehicleFloatParam(VEHICLE_VERTICAL_ATTRACTION_EFFICIENCY, 0.5);

llSetVehicleFloatParam(VEHICLE_VERTICAL_ATTRACTION_TIMESCALE, 1.0);

llSetVehicleFloatParam( VEHICLE_HOVER_HEIGHT, 0.0); // set ball at water surface

llSetVehicleFloatParam( VEHICLE_HOVER_EFFICIENCY, 0.5 );

llSetVehicleFloatParam( VEHICLE_HOVER_TIMESCALE, 1.0 );

}

These are the controls and they work fine in ubODE, but CONTROL_UP and CONTROL_DOWN do nothing in Bullet.

control(key id, integer level, integer edge)

{

float gForwardThrust; // variable for forward thrust

float gReverseThrust = -1.5; // reverse thrust backup speed

if(level & CONTROL_FWD)

{

Swimming();

gForwardThrust = 3; // normal forward speed

vTarget = llGetPos(); // get our current position

// if near region edge, slow down

if (vTarget.x > xlimit || vTarget.x < gGuard || vTarget.y > ylimit || vTarget.y < gGuard)

{

if (vTarget.x > xlimit) vTarget.x = xlimit;

if (vTarget.x < gGuard) vTarget.x = gGuard;

if (vTarget.y > xlimit) vTarget.y = ylimit;

if (vTarget.y < gGuard) vTarget.y = gGuard;

gForwardThrust = .3; // slow us down

llWhisper(0, "Approaching sim edge, drive away...");

}

if ( vTarget.z < (llGround ( ZERO_VECTOR ) + 0.35) )

{ // too shallow and going to collide with land

gForwardThrust = .05; // slow us down

llWhisper(0, "Too shallow, drive away...");

}

llSetVehicleVectorParam(VEHICLE_LINEAR_MOTOR_DIRECTION, <gForwardThrust,0,0>);

}

if(level & CONTROL_BACK)

{

llSetVehicleVectorParam(VEHICLE_LINEAR_MOTOR_DIRECTION, <gReverseThrust,0,0>); // back us up

return;

}

if(level & (CONTROL_UP))

{

HovHeightBase = HovHeightBase + 0.02;

llSetVehicleFloatParam( VEHICLE_HOVER_HEIGHT, HovHeightBase);

}

if(level & (CONTROL_DOWN))

{

HovHeightBase = HovHeightBase - 0.02;

llSetVehicleFloatParam( VEHICLE_HOVER_HEIGHT, HovHeightBase);

}

if(level & (CONTROL_RIGHT|CONTROL_ROT_RIGHT)) llSetVehicleVectorParam(VEHICLE_ANGULAR_MOTOR_DIRECTION, <0, 0,-5.0>);

if(level & (CONTROL_LEFT|CONTROL_ROT_LEFT)) llSetVehicleVectorParam(VEHICLE_ANGULAR_MOTOR_DIRECTION, <0, 0, 5.0>);

if(edge & ~level & (CONTROL_FWD|CONTROL_BACK)) Treading();

}

I might add this is actually from my swim ball script which also works just fine in ubODE but fails in Bullet on the dive and surface actions.

In bullet nothing at all happens.

Is this a bug in opensim? I know it is expected a script that works in one physics engine is suppose to work in the other physics engines as well.

Not being an expert at script writing, it is possible I stumbled into doing something wrong that ubODE can deal with and Bullet can’t.

Tom

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AJLDuarte

Re: ubODE vs. Bullet

Hi,

ubOde and bullet where created in parallel so naturally had different interpretations of details and implementation.

Making them more identical is a slow and hard going on process.

To check if ubode or bullet are more corret on a feature, one needs to compare to original reference.

This does not mean we will not add Opensim extensions, but those will be flagged as such

Old ODE has its very own idea of vehicles (should no longer be used on new regions)

On this case ubOde seems correct… but then im biased on that ;)

Ubit

From: [hidden email] [mailto:[hidden email]] On Behalf Of [hidden email]
Sent: Monday, May 01, 2017 04:28
To: OS-Opensim Users
Subject: [Opensim-users] ubODE vs. Bullet