[Opensim-users] ubODE vs. Bullet

[tringate at gmail.com]

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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