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MS3D - Problem displaying the Bones


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#1 novousmihi   Members   -  Reputation: 108

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Posted 02 July 2009 - 01:17 AM

Hi, I have a pretty decent 3D engine. I can draw models, sprites, load textures without a problem, and I can fly around with my cam, use lights and all the basic stuff. I have been putting this off for way too long - but I've finally taken the step to actually make the models do something. The problem is, I can't display my bones correctly. If I draw them like points, they appear like they should, assuming that bones[...].position[...] in the ms3d spec file is the joints absolute x-,y-,z- coordinates and not anything relative to a given position - like its parent-joint. I try to connect the joints positions with a line for every joint that has a parent, that is I push two vertices at a time into a vertexbuffer in the order: parent, child, parent, child, parent, child,... and then render the buffer like a list of separate lines with D3DPT_LINELIST. My problem is that I get these failed bones: The Failed Bones Compared to how they should be: The bones in Milkshape 3D Below is the linkage between all the joints in psuedo-code. (A correct text-dump of the actual MS3D-file) Each valid joint is linked with the indexes of the parent- and child- joints. Much the same as how the triangles are linked through the indexes of the vertexbuffer. So the syntax in the bone-list below is: bone( index ) = ( parent-joint, child-joint ) I can't see where the problem is... Everything seems fine in the dump file. Tey seem correctly linked. And I have loaded the file correctly, that much I know for sure. I've double-checked with an MS3D text-dump of the same file. Any help would be appreciated, and if you can't see a problem in my logic or how I've linked the bones or how I've rendered them, then that would also be appreciated so I atleast know that much. Is the problem with the rendering of the bones or the linking of them?
Model(...)
{
	Vertices( 839 )
	Triangles( 1007 )

	Mesh Groups( 2 )
	Materials( 5 )

	Textures( 5 )
	Joints( 28 )
	Bones( 27 )

	Frames( 300 )
	FPS( 25.00 )

	Bonelist
	{
		Bone(0) = { 0, 1 }
		Bone(1) = { 1, 2 }
		Bone(2) = { 1, 18 }
		Bone(3) = { 1, 23 }
		Bone(4) = { 2, 3 }
		Bone(5) = { 3, 4 }
		Bone(6) = { 4, 5 }
		Bone(7) = { 5, 6 }
		Bone(8) = { 5, 8 }
		Bone(9) = { 5, 14 }
		Bone(10) = { 6, 7 }
		Bone(11) = { 8, 9 }
		Bone(12) = { 9, 10 }
		Bone(13) = { 10, 11 }
		Bone(14) = { 11, 12 }
		Bone(15) = { 12, 13 }
		Bone(16) = { 14, 15 }
		Bone(17) = { 15, 16 }
		Bone(18) = { 16, 17 }
		Bone(19) = { 18, 19 }
		Bone(20) = { 19, 20 }
		Bone(21) = { 20, 21 }
		Bone(22) = { 21, 22 }
		Bone(23) = { 23, 24 }
		Bone(24) = { 24, 25 }
		Bone(25) = { 25, 26 }
		Bone(26) = { 26, 27 }
	}
	Jointlist
	{
		Joint(Joint1).Index: 0
		{
			ParentName: 
			ParentIndex: -1
		}
		Joint(Joint2).Index: 1
		{
			ParentName: Joint1
			ParentIndex: 0
		}
		Joint(Joint3).Index: 2
		{
			ParentName: Joint2
			ParentIndex: 1
		}
		Joint(Joint4).Index: 3
		{
			ParentName: Joint3
			ParentIndex: 2
		}
		Joint(Joint5).Index: 4
		{
			ParentName: Joint4
			ParentIndex: 3
		}
		Joint(Joint6).Index: 5
		{
			ParentName: Joint5
			ParentIndex: 4
		}
		Joint(Joint7).Index: 6
		{
			ParentName: Joint6
			ParentIndex: 5
		}
		Joint(Joint8).Index: 7
		{
			ParentName: Joint7
			ParentIndex: 6
		}
		Joint(Joint9).Index: 8
		{
			ParentName: Joint6
			ParentIndex: 5
		}
		Joint(Joint10).Index: 9
		{
			ParentName: Joint9
			ParentIndex: 8
		}
		Joint(Joint11).Index: 10
		{
			ParentName: Joint10
			ParentIndex: 9
		}
		Joint(Joint12).Index: 11
		{
			ParentName: Joint11
			ParentIndex: 10
		}
		Joint(Joint13).Index: 12
		{
			ParentName: Joint12
			ParentIndex: 11
		}
		Joint(Joint29).Index: 13
		{
			ParentName: Joint13
			ParentIndex: 12
		}
		Joint(Joint14).Index: 14
		{
			ParentName: Joint6
			ParentIndex: 5
		}
		Joint(Joint15).Index: 15
		{
			ParentName: Joint14
			ParentIndex: 14
		}
		Joint(Joint16).Index: 16
		{
			ParentName: Joint15
			ParentIndex: 15
		}
		Joint(Joint17).Index: 17
		{
			ParentName: Joint16
			ParentIndex: 16
		}
		Joint(Joint18).Index: 18
		{
			ParentName: Joint2
			ParentIndex: 1
		}
		Joint(Joint19).Index: 19
		{
			ParentName: Joint18
			ParentIndex: 18
		}
		Joint(Joint20).Index: 20
		{
			ParentName: Joint19
			ParentIndex: 19
		}
		Joint(Joint21).Index: 21
		{
			ParentName: Joint20
			ParentIndex: 20
		}
		Joint(Joint22).Index: 22
		{
			ParentName: Joint21
			ParentIndex: 21
		}
		Joint(Joint23).Index: 23
		{
			ParentName: Joint2
			ParentIndex: 1
		}
		Joint(Joint24).Index: 24
		{
			ParentName: Joint23
			ParentIndex: 23
		}
		Joint(Joint25).Index: 25
		{
			ParentName: Joint24
			ParentIndex: 24
		}
		Joint(Joint26).Index: 26
		{
			ParentName: Joint25
			ParentIndex: 25
		}
		Joint(Joint27).Index: 27
		{
			ParentName: Joint26
			ParentIndex: 26
		}
}

struct Bone{
    unsigned short parentIndex;
    unsigned short childIndex;
}

[Edited by - novousmihi on July 3, 2009 8:28:17 AM]

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#2 Caste   Moderators   -  Reputation: 969

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Posted 03 July 2009 - 06:06 AM

I didn't look into MS3D recently, but from what you get it seems as if the child bone positions are relative to the parent's position (and probably orientation). Thus you might want to apply the transformation matrix of the parent node to it's children too.

Just my thoughts :)

#3 novousmihi   Members   -  Reputation: 108

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Posted 03 July 2009 - 06:48 AM

I found the problem, after 2 days excessibe programming.

The problem was I used the pos[..] information from the ms3D spec.
I should have used the floats 41 to 43 in the mFinal matrix for each joint as the coordinate information.

#4 novousmihi   Members   -  Reputation: 108

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Posted 03 July 2009 - 06:52 AM

Quote:
Original post by Caste
I didn't look into MS3D recently, but from what you get it seems as if the child bone positions are relative to the parent's position (and probably orientation). Thus you might want to apply the transformation matrix of the parent node to it's children too.

Just my thoughts :)


Thanks man, I just found the problem.
I might as well type it here if more people have this kind of problem.

I had to use the pos and rotation information from the joint and
create a rotational matrix and a translational matrix and then
multiply them into one to get mFinal:

CreateRotationXYZ(&rots, pitch,yaw,roll);
CreateTranslation(&trans, x,y,z);

mFinal = rots * trans;



Though my programming book did not state this as well as it should have...





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