94 lines
3.9 KiB
TeX
94 lines
3.9 KiB
TeX
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\subsection{Animation}
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The objective of this part is to animate the mesh we previously generated
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around the skeleton. We have as an input segments of the skeleton, and its
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mesh. The idea is to deform the segments of the skeleton, and to
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automatically have the impact of this deformation on the vertices of the
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mesh.
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\subsubsection{Trees}
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When we will animate our mesh, we want to keep it as one piece. For
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example, when you move your arm, your elbow and your forearm follows
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the movement of your arm. This means that the transformation that we
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will apply after the shoulders must be kept on the arms and forearms.
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To manage to do this, we structured everything in trees. The tree for a
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person will be the following for example (to simplify, we will take the
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hypothesis that this human has no knees).
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\begin{figure}[H]
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\centering
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\begin{tikzpicture}
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% Head
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\draw (0,0) circle [radius=1];
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\draw (0,0) node{Head};
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% Left son of head
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\draw (0,-1) -- (-3,-2);
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\draw (-3,-3) circle [radius=1];
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\draw (-3,-3) node{Left arm};
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% Left son of left arm
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\draw (-3,-4) -- (-6,-5);
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\draw (-6,-6) circle [radius=1];
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\draw (-6,-6) node{Left forearm};
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% Middle son
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\draw ( 0,-1) -- ( 0,-2);
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\draw ( 0,-3) circle [radius=1];
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\draw ( 0,-3) node{Body};
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% Left leg
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\draw (0, -4) -- (-2, -5);
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\draw ( -2,-6) circle [radius=1];
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\draw ( -2,-6) node{Left leg};
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% Right leg
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\draw (0, -4) -- (2, -5);
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\draw ( 2,-6) circle [radius=1];
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\draw ( 2,-6) node{Right leg};
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% Right son
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\draw (0,-1) -- (3,-2);
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\draw (3,-3) circle [radius=1];
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\draw (3,-3) node{Right arm};
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% Left son of left arm
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\draw (3,-4) -- (6,-5);
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\draw (6,-6) circle [radius=1];
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\draw (6,-6) node{Right forearm};
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\end{tikzpicture}
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\caption{Tree for a human being skeleton}
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\end{figure}
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\paragraph{}
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At each node of this, there will be a rotation (with a center, and
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angles), and we will draw the animated mesh by traversing the tree.
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At each node, we will apply the transformation of the current node, and
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then draw the subtree.
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Of course, we also need to know what faces are in each nodes, so we
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will have a tree of rotations, and a tree of faces.
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\subsubsection{Junctions processing}
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All we said before is valid only if the three vertices of a face are
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mapped to the same segment. But some faces have vertices that are
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mapped to different segments. For these faces, we need to apply a
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different transformation for each vertex.
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For this purpose, we created a hashtable between vertex numbers and
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paths in trees so that we are able to find the transformation for these
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vertices.
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\subsubsection{Graphical User Interface}
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In order to be able to manipulate the animated mesh easily, two graphical interfaces were made :
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\begin{enumerate}
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\item the first one allows the user to add rotation points to the
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skeleton (by default, only the junction points are considered
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as rotation points, and there are no knees and elbows for
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example).
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\item the second one has the OpenGL rendering and a menu controlled
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with the keyboard, allowing the user to select rotation points
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and to change the value of the angles.
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\end{enumerate}
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