In order to create the bird creatures for my project I needed to combine the techniques I explored in my previous post. In order to do this I started with the creature sketch I created before. Here the creature is a Mover object (as seen in previous posts) and is attracted to the circle (which can also be moved by the mouse).
The Creature Sketch. You can move the circle by dragging it.
Next I added some “wings” to the creature by adding some functionality I learned from my oscillation experiments. First I gave the Mover object some more PVectors which are needed to create the oscillation functionality, angle, amplitude and oscillationVelocity. I then created a oscillate function which adds the oscillation velocity to the angle. The position of the oscillation is then calculated like before by multiplying the sine of the angle by the amplitude. I then passed the resulting x and y values to an ellipse with a center of (0,0). The resulting sketch is below:
Obviously this is a poor approximation of the movement of wings, so I looked into the biomechanics of pigeon flight to gain a greater understanding of the way the birds in my Processing sketch should move. Looking at the traces that real-life pigeons wings follow in real life would me envision what an approximate would look like.
Wing kinematics differ depending upon a bird’s wing design and flight speed. (A) Birds with pointed, high-aspect ratio wings such as the pigeon Columba livia transition from tip-reversal upstrokes during slow flight to feathered upstrokes at intermediate speeds and a swept-wing upstroke during fast flight. (B) Birds with rounded, low-aspect ratio wings such as the black-billed magpie Pica hudsonica use a flexed upstroke at all flight speeds. Shown are wingtip (filled circles) and wrist (open circles) paths in dorsal and lateral view (from Tobalske and Dial, 1996).
Reading up on the biomechanics of bird flight I learned that pigeons create a wide arc using their wings and they do not flap them very fast. The tip of the wing at the height of the flap is angled high up from the body and angles slightly away from the head. As the wing flaps down, it goes straight down but on return the wing is slightly tucked into the body. Think of a “windmilling” action that children sometime do during play, the pigeon’s bird flap is somewhat similar.
Here’s my first attempt at creating an approximation of wings. I added two instances of the wing ellipses, one with positive and one with negative velocities. Obviously this wing animation needs some more work. In this sketch I also added a tail to the birds, to see how adding more shapes to the object would effect the outcome. I also used an array to create more instance of the birds so I could see how the added movement and intereaction affected the overall outcome.Next I will do some more visual testing to improve the aesthetic quality of the birds and the piece in general.
Shiffman, D., 2012. The Nature of Code [online] Mountain View: Creative Commons
Tobalske, B., 2007. Biomechanics of Bird Flight. Journal of Experimental Biology [online] 210 (3135-3147).