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Arbitrary Axis?
January 09, 2003 03:42 PM
Hi, Im currently rotating a 3d object i''ve loaded, but I have a problem. It always rotates about the origin! It''s a jeep, so instead of spinning left, it is swing in a wide arc to the left, as if it were still attached to the origin point. This of course only happens when I move the object away from the origin, it behaves correctly when it hasn''t been moved. Help?
122
January 09, 2003 04:25 PM
the order you do your transformation in is important here since it''s all based on matrix-multiplication which isn''t kommutative..so to solve your problem: first rotate (while the object is centered at the origin), then translate.
Runicsoft -- home of my open source Function Parser and more
Runicsoft -- home of my open source Function Parser and more
January 09, 2003 06:40 PM
thanks! well, now it rotates according to itself no matter what, but I can't move it correctly. When I rotate the object, it moves in different directions. I think it has to do in my matrix multiplications: here's my code:
These two calls are made at different points in the program, such that while checking for keystrokes I call the move (and the rotatex, y, and z functions) then I call an update of the object before rendering. Any help?
[edited by - Funkymunky on January 9, 2003 7:43:59 PM]
[edited by - Funkymunky on January 11, 2003 2:53:27 AM]
[edited by - Funkymunky on January 11, 2003 2:54:00 AM]
// Move, by amount vector vD3DXMATRIX R, Rx, Ry, Rz;D3DXVECTOR3 Dir;D3DXMatrixRotationZ(&Rz, roll);D3DXMatrixRotationX(&Rx, pitch);D3DXMatrixRotationY(&Ry, yaw);R = Rz * Rx * Ry;Dir.x = (v.x*R._11)+(v.y*R._21)+(v.z*R._31);Dir.y = (v.x*R._12)+(v.y*R._22)+(v.z*R._32);Dir.z = (v.x*R._13)+(v.y*R._23)+(v.z*R._33);Pos+=Dir;// Update, perform all rotations and movementsD3DXMATRIX R, T, Rx, Ry, Rz;float x, y, z;D3DXMatrixTranslation(&T, Pos.x, Pos.y, Pos.z);D3DXMatrixRotationX(&Rx, -pitch);D3DXMatrixRotationY(&Ry, -yaw);D3DXMatrixRotationZ(&Rz, -roll);R = Rz * Rx * Ry * T;// for all vertices, this is how i compute the new positionx = vertices[i].position.x * R(0, 0) + vertices[i].position.y * R(1, 0) + vertices[i].position.z * R(2, 0) + R(3, 0);y = vertices[i].position.x * R(0, 1) + vertices[i].position.y * R(1, 1) + vertices[i].position.z * R(2, 1) + R(3, 1);z = vertices[i].position.x * R(0, 2) + vertices[i].position.y * R(1, 2) + vertices[i].position.z * R(2, 2) + R(3, 2); These two calls are made at different points in the program, such that while checking for keystrokes I call the move (and the rotatex, y, and z functions) then I call an update of the object before rendering. Any help?
[edited by - Funkymunky on January 9, 2003 7:43:59 PM]
[edited by - Funkymunky on January 11, 2003 2:53:27 AM]
[edited by - Funkymunky on January 11, 2003 2:54:00 AM]
January 11, 2003 09:57 PM
Ok, I fixed up the obvious errors in the code, and it worked. I call a move in the y direction, and the car moves toward the Z. Now, if I have a camera defined in the same manner (Position and a roll, pitch, yaw) how could I attach it to the object?
241
January 12, 2003 04:06 AM
as we are already talking about transformations
i have a question about keyframe animations
i have the bones with their rotation info
how do i render such a model
because you have faces whose vertices are attached to multiple bones
should i precalculate the geometry or should i only precalculate the polygons which have been assigned to multiple bones and then render the rest with modelview transformations?
i have a question about keyframe animations
i have the bones with their rotation info
how do i render such a model
because you have faces whose vertices are attached to multiple bones
should i precalculate the geometry or should i only precalculate the polygons which have been assigned to multiple bones and then render the rest with modelview transformations?
http://www.8ung.at/basiror/theironcross.html
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