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$20 to anyone who can figure out whats wrong with this code.

General and Gameplay Programming Programming

Started by CodaKiller January 20, 2009 11:16 AM

26 comments, last by phresnel 15 years, 3 months ago

CodaKiller

108

Author

January 20, 2009 06:52 PM

Quote:Original post by M2tM
This may help, it's basically exactly what I do in opengl for rotating around a specified origin:
*** Source Snippet Removed ***

NOTE: atOrigin() is a function that basically checks to see if the vector is 0, 0, 0

See the rotate part? That's where you can specify to rotate around a specified origin.

However you do that in directx would be it.

Not sure if this is helpful. I store objects with a local translation and scale value and then also a rotation value and a rotation origin. That is what all these points relate to... It sounds like you're already doing this though and the problem lies with your shader (which I am not familiar with), so this is more an explanation to the people asking you why you're doing what you are.

Thats what I'm already doing, I translate it to the origin I want then I multiply it by the rotation and then move it back to it's original position.

Thats at "// I thought the code below would give the matrix the correct center of rotation but it's still at the origin." which is actually working but it's not moving it to the right origin or something else is wrong thats making it the wrong origin, idk...

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M2tM

948

January 20, 2009 07:25 PM

Ah, I see, that picture is a "desired effect" so my opengl version transcribed into direct x would probably solve you. I mis-read and thought that second picture with the two bones rotated on the second bone's pivot was what you had working.

Have you made sure your rotation origin is what you think it is? Try stepping through the bugger with a debugger.

and go through my example and make sure each step is actually being done.

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Cornstalks

7,033

January 20, 2009 08:05 PM

CodaKiller, did see janta's post about the type of matrix D3D functions expect? I just want to point it out again to make sure that you see it. D3D expects row major matrices. However, you're getting a column major matrix.

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MortusMaximus

159

January 20, 2009 08:35 PM

I'm not too experienced with directx, but I am familiar with this process that you are trying to do. It looks like you only set inv_world once, instead of for each bone. If you use the same inv_world translate matrix for each bone, they will use the same point of rotation.

Here is an image to hopefully explain better:

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CodaKiller

108

Author

January 21, 2009 02:10 AM

Quote:Original post by MikeTacular
CodaKiller, did see janta's post about the type of matrix D3D functions expect? I just want to point it out again to make sure that you see it. D3D expects row major matrices. However, you're getting a column major matrix.

Quote: NOTE: While Direct3D matrices are technically row major, they have an additional semantic difference to OpenGL matrices which cancels this out; therefore, use this same code for Direct3D.

This is from the PhysX documentation, it's talking about the getColumnMajor44 command and of course I would have made sure I had a working matrix before I would have posted here.

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CodaKiller

108

Author

January 21, 2009 10:15 AM

Quote:Original post by MortusMaximus
I'm not too experienced with directx, but I am familiar with this process that you are trying to do. It looks like you only set inv_world once, instead of for each bone. If you use the same inv_world translate matrix for each bone, they will use the same point of rotation.

Here is an image to hopefully explain better:

inv_world is just to bring the object back out of model space, it's not possible to compute it for each bone since then it would be the same thing as using identity on all of the matrices.

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CodaKiller

108

Author

January 21, 2009 10:47 AM

Aha! This explains exactly what I need to do! Finally found something! Whats sad is I was doing something similar but then I thought it was wrong and just delete it.

[Edited by - CodaKiller on January 21, 2009 11:47:06 AM]

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RabblePants

548

January 21, 2009 01:07 PM

So, out of curiosity, what your mistake?

CodaKiller

108

Author

January 21, 2009 02:25 PM

Quote:Original post by Grafalgar
So, out of curiosity, what your mistake?

Pretty much all of that code was wrong, it needed to be done in a completely different way.

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VerMan

116

January 21, 2009 02:45 PM

Who gets the $20?

$20 to anyone who can figure out whats wrong with this code.

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$20 to anyone who can figure out whats wrong with this code.

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