Angular Velocity

string db[15];



action rotate {

	var prev[3];

	var total = 0;

	vec_set(prev,my.pan);

	

	while(1) {

		vec_diff( temp, my.pan, prev );

		vec_set(prev,my.pan);

		vec_scale( temp, 1/time );

		total = vec_length(temp);

		

		str_for_num( db, total );

		draw_text( db, 50, 170, vector(100,100,255));

				

		str_for_num( db, temp[0] );

		draw_text( db, 50, 50, vector(255,100,100));

		str_for_num( db, temp[1] );

		draw_text( db, 50, 90, vector(255,100,100));

		str_for_num( db, temp[2] );

		draw_text( db, 50, 130, vector(255,100,100));



		my.pan += 3*time;

		my.tilt += 3*time;

		my.roll += 3*time;

		wait(1);

	} //while



} //

action physics_rotate {

	ph_setgravity( nullvector );

	phent_settype( my, PH_RIGID, PH_BOX );

	phent_setmass( my, 1, PH_SPHERE );

	phent_setdamping( my, 0, 0 );



	var prev[3];

	var total = 0;

	

	vec_set(prev,my.pan);



	phent_addtorqueglobal( my, vector( 30, 30, 30 ) );

	

	//for this to work make sure object is not on the floor

	while(1) {

		vec_diff( temp, my.pan, prev );

		vec_set(prev,my.pan);

		vec_scale( temp, 1/time );

		total = vec_length(temp);

		

		str_for_num( db, total );

		draw_text( db, 50, 170, vector(100,100,255));

				

		str_for_num( db, temp[0] );

		draw_text( db, 50, 50, vector(255,100,100));

		str_for_num( db, temp[1] );

		draw_text( db, 50, 90, vector(255,100,100));

		str_for_num( db, temp[2] );

		draw_text( db, 50, 130, vector(255,100,100));	

		

		wait(1);

	} //while



} //

Quote:

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Is this useful behavior ? If not what kind of information would you like to have returned ?

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Quote:

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The idea behind phent_getvelocity() was to find out how fast a certain point is moving. When you bump into another object you can call getvelocity in the event function to determine if it was a high-speed crash or just a minor dent.

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Which is perfect for Linear collisions, but, and this is just my opinion, it doesn't seem to be so hot for rotational collisions.

Question: How is rotational collsions handled?

For eg, I have two thik disks rotating about their z-axis (vinyl record like). As I bring their edges, together slowly, adiabatically (so as to minmize the linear collision dynamics), at some point the edges come into contact and the collision is purely rotational. By my current understanding of the PE a tangential velocity will be calculated for each of the points of contact and then some kind of momentum conservation is done? By your words then, this is done on global coordinates...how is this then translated to local motion???

Im thinking that perhaps, alot of the jitters and other myriad of collision bugs could in fact be due to inconsistencies in the rotational collision or in the handling of rotations?

Quote:

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I could easily return the angular velocity vector - would that help ?

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I would much rather display three ang vel vectors (omega(about z), omega(about y), and omega(about x)) and if I'm constantly rotating about z, for eg, omega(z) would remain constant and the others zero. This is motivated in part by the fact that when I torque an entity, I do so about a local axis. Thus, one can see a positive corrolation between ang vel change (ang acc or alpha) and applied torque. In the above record example, if I had two columns, one for torque(about axis) and another for alpah(about axis), I could for example see a "10" in the z-torque column and then see that my ang_vel(about z) is steadily increasing.

When it comes to car physics, if these omegas are local, then you align the x axis with the front of the car. If omega(x) gets too out of hand, you can either pause the physics engine and my.roll it back into place or keep the PE on and torque it back into place.


BUT THATS JUST ME.....OTHERS NEED TO SPEAK ON THIS ISSUE TO REALLY GAUGE WHETHER THIS IS THE BEST WAY TO GO AND IF ANYTHING i SAID MAKES SENSE .