The animated .GIF of the Weekender hull was created using an Excel spreadsheet (Righting_Moment.xls), the Print Screen button, MicroSoft Paint, and the GIMP, (Gnu Image Manipulation Program).
Each frame of the animation is in fact a Print Sreened copy of the Tilted
worksheet of the Excel spreadsheet
Righting_Moment.xls.
The widths and the heights of all of the cells of the Tilted worksheet were set
to twelve pixels to produce a screen of cells with square proportions. A
conditional format statement was pasted into each cell to flip the background
color to either white, green, gray, or blue depending on the specific density of
the material contained in each cell. The default white color was for empty
cells, green for densities greater than zero, blue for negative densities
(buoyancy), and gray for an arbitrary nearly-zero constant for the water. Then
the entire worksheet was Zoomed to 10% size to produce a view of the
worksheet where each cell was one pixel on the screen. At one pixel high by one
pixel wide, Excel has no fonts small enough to attempt to display the contents
of the cells, so all that shows is the background color. Viola, a picture is
displayed on the screen.
A set of 31 images was produced where each image depicted the hull at different stages of heel from 0 to 30 degrees. Each image was successively pasted into Paint and save as "Tilted_nn.gif" where nn indicated the degrees of heel. I suppose I could have used the GIMP instead of Paint to save the original images, but that's a little like using a sledge hammer to drive tacks.
The individual frames were knitted together to form the animation using the
open source GNU Image Manipulation Program (GIMP). The animation starts with the
Titled_00.gif frame. Then the Layers dialog box was opened and a new Empty
Layer created. Opening each image in turn, copying and anchoring
the image to a new Empty Layer builds up the animation. Thirty New Layers later
and the hull was rotating to starboard through thirty degrees. Since I have not
figured out if there is any way to control the time interval between successive
frames (the default seems to be 100 milliseconds) and I wanted the roll rate to
slow down has the hull reached its maximum roll angle before reversing, I ended
up replicating the more tilted frames from 20 to 30 degrees until the roll rate
looked realistic with the number of frames at each stage of tilt proportional
to cos ø for a constant change in ø. Making a second copy of all the Layers and
reversing their order returns the hull to upright. Making another copy of all
of the layers and reversing the images in each copied layer rotates the hull
out to thirty degrees port and back.
The final steps in the production are to make another copy of the entire animation and Optimize the images for animation, which reduces all the other Layers to just the net changes from frame to frame and thereby reduces the size of the resulting .GIF to a fraction of its former self.
It took about an hour to produce and save the original 31 images, another hour or two to figure out how the GIMP layer tools work, and another hour after that to cut and paste and replicate all of the layers. But I think the results were worth it, and again, it annoys the guys at work who think I have too much time on my hands.
