RE: [Plib-users] 'World' to 'Local' body velocity transform

[McEvoy, N. <nic...@ds...>]

"Steve" wrote:
>So (in a nutshell) you want to transform the world-coordinate velocity into
>'body' coordinates.

Thanks for that (nice summary too) !!!

Yes, I have read 'Matrices can be your Friends' too.  Good stuff !  :-)

So ... your_words-to-code seems to be something like this (just the velocity
conversion part from world-to-body) ...

{...

	sgVec3 HPR, Velocity;
	sgMat4 R1, VM;

	// world velocity
	sgSetVec3(Velocity, 0, 100, 0);

	// testing heading changes
	for (int i = 0; i >= -180; i-=45)
	{
		sgSetVec3(HPR, (float)i, 0, (float)i);

		sgMakeRotMat4(R1, HPR);
		sgInvertMat4(R1);
		sgMakeTransMat4(VM, Velocity);
		sgPreMultMat4(R1, VM);

		// body velocity
		sgCoord vel;
		sgSetCoord(&vel, R1);

		printf("HPR <%0.2f> <%0.2f> <%0.2f>\n", HPR[0], HPR[1],
HPR[2]);
		printf("BodyVel <%0.2f> <%0.2f> <%0.2f>\n", vel.xyz[0],
vel.xyz[1], vel.xyz[2]);
	}

...}

Thanks for your suggestion ... I will add it to my game tonight and see if
it fixes my problem ...

Nick
_________________________________________

Nick McEvoy
WorkMail: mailto:nic...@as...
HomeMail: mailto:ndm...@oz...
HomePage: http://members.ozemail.com.au/~ndmcevoy/
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