Weird_Bird -- A Motion Hierarchy Animation By Marcus Brooks The Weird_Bird animation was created to provide an example of motion hierarchies. In flight, the bird has a an overall motion, an up-and-down rythm caused by the beat of its wings. The wings themselves have a motion as well, the swinging arc of their beat, and the flapping of their flight feathers. In addition, the tail pulses up-and-down in countercadence to the bird's body. All of these motions are combined so that one part's motion is likely to be described by several factors. The complexity of this rather simple motion can be almost mind-boggling, if you imagine trying to accurately describe it in mathematical terms, and then translate it by hand into positional data for a computer. Part of the beauty of this motion, then, is that it can be described with surprising ease in Sculpt Animate 3D. The Weird_Bird object itself was created with three primary goals in mind: visual realism, realistic movement, and a minimal number of vertices for faster editing and rendering. The object was in some ways harder to create than the motion. It was done almost entirely by hand-placing vertices in the tri-view and building edges between them. This sort of object creation generally leads to a cleaner, more easily animated object with fewer vertices, since it must be based on an understanding of the genuine article's structure. This places some demands on the designer, but also on the software. Sculpt Animate 3D's interactive editing environment is absolutely essential for this sort of object creation. The object was created in just a few hours, by a non-artist. This file is interested not so much in the object itself, but in how it came to be animated. Most of the details of how this works are in the manual, so this is simply a step-by step list of what tools were used, and when. 1) The bird object was created. I can't help you much here, I just picked a bird that I had studied some, and used it as a basis (see if you can guess what it is). There were some considerations, however, that I had in mind. -- A bird's wing flaps from the shoulder, and is thickest at the shoulder. The bird object's shoulder is a half-ring of vertices that provides the desired effect -- A bird's wing structure fans out from a place near the center of the leading edge (ignoring some structure for simplicity). Thus the entire wing (beyond the body) is five vertices, four that fan out from a fifth at the leading edge. The shoulder is connected so that the wing appears solid along the inner leading edge, but the outer panel is a single thickness. -- A bird's tail fans out similarly, pivoted at the base. 2) One of the wing path curves was created. It started out as a 20 subdivision circle, but three vertices on the "upswing" side were selected and subdivided once, making 22 vertices. This slows down the upswing of the wing, making the downbeat seem faster. The circle was shrunk to a tight vertical ellipse, tilted forward some, and then curved toward the bird's body to make the path arc. The curving is done by selecting progressively smaller portions of the ellipse, and "bending" it with the rotate gadgets. MAKE PATH was used to make the curve a path. 3) The second wing path was created by selecting the path, centering the cursor on the bird's body and doing a REFLECT. Then the resulting new curve was made a path with MAKE PATH. Make sure both paths start at the same vertex. 4) MODIFY INDICATED TUMBLE was used to walk around each wing path, adjusting the tumble axes so that the five vertices that make up the wing would tilt and flap to match the wing's motion. 5) The left wing's path was indicated and NAME INDICATED PATH was called. The following hierarchy names were entered. +--bird | birdpath--+--lwingpath----lwing | +--rwingpath----rwing | +--tailpath-----tail These names can all be entered now, they don't need to be attached to anything right away, in the meantime they are tagged "empty". After the names were entered, "lwingpath" was made the current name and OK was clicked, naming the path. Then the other path was indicated and ESC was hit to recall the NAME INDICATED PATH command again. This time "rwingpath" was clicked into the current slot and OK clicked. Be careful not too click OK unless you mean to!! It's a good habit to get used to clicking CANCEL, this way you can't accidentally rename something when you are just browsing. 6) A similar 22-vertex loop path was made for the tail, with the tumble axes set to wag the tail up and down more-or-less in rythm with the wings. Since all we care about here is the tumble axes, the path was made very small. The path was given the name "birdpath+tailpath" (tailpath, offspring of birdpath). 7) Another 22-vertex loop path was made, this one shrunk to a small vertical ellipse in the center of the bird. The starting point on this ellipse was placed opposite the starting point on the wing paths, as was the extra two-vertex subdivision. This gives the whole bird an "equal and opposite" motion to balance the wing motion. This path was given the name "birdpath" on the top level. 8) Once everything was set, the local origins were set for each object. The tail's local origin is in its base, each wing's local origin is near its leading edge vertex, and the bird's local origin is in its center. One more thing. There are three paths attached to "birdpath". Remember that anything that's attached to a path will probably need a local origin setting, including other paths! The local origins for all three "sub-paths" are set to their centers. It can be confusing when you have paths attached to paths, and you want to know the effect of the local origin. Remember that the local origin of an object (or path) is the part OF THAT OBJECT that follows along the path higher up. 9) The animation is essentially finished. Load take is called and a name given to it. Modify Take is called, the Number of frames set to 22, and the global scene saved with SAVE GLOBAL SCENE. Now PREVIEW or RENDER ALL can be called. A few PREVIEWs would be in order, as well as RENDER FRAME in the FRAME mode requester. This prevents "surprises". Once the animation is rendered, enjoy!