Animating
the pages of a book
The assignment is actually quite simple. Making the pages of a book turn over by the wind, as in this animation. Despite that giving, it took me quite a while to find a method which makes the whole thing as uncomplicated as possible. The biggest problem being that not just one page of the book should be turned over, but multitude of them. And if possible not all with the same texture, every page in a book looks different after all.
Let's start with a single page. Draw a spline in the front viewport which resembles half of an open book (more or less like the one in the image to the left). What's important is that there are only 2 vertices in the upper segment (as displayed in the image). This is a prerequisite in being able to animate the pages easily. In addition, You should make sure that the vertex that makes up the middle of the book lays on the world center axis (the black line). That way it is easier to mirror the other half of the book. The best way to make sure it is, is by enabling snaps
(in the menu list to the bottom, the magnet with the 3 besides it). Your cursor will then snap to the grid in Your viewport, and allows You to draw the spline precisely.
Next, extrude the spline You have just drawn, by selecting the modifier panel
, and selecting the "Extrude modifier. Enter a value which gives Your half of the book its right proportions. My half of the book is almost 200 units wide, so I extruded it by 250 units, giving me nice portrait-sized pages. Your half of the book should look somewhat like the one in the image to the left.
Now mirror this half book by choosing the World coordinate system
and selecting "Use Transform Coordinate Center"
. You should see the transformation center of the book moving to the position of the 'middle' vertex. Now click the "Mirror" tool
, and choose the X-Axis as the Mirror Axis, choosing "Copy" under the "Clone Selection" options. And Your book is done... well, at least the beginning of it. I will leave the book-jacket be, this is really only about the pages. It is included in the downloadable example file though..
Now all we need is a page to turn over. To make one, start by activating "Select & Move"-tool
, press and hold the shift key, and click on the left half of the book (but don't move it!). After You let go of the mouse button, a dialog with cloning options will appear. Choose "Copy" and confirm by clicking "OK". Doing this will get You an exact copy of the left half of the book on the exact same spot as the original.
Now go back into the Modify panel
.
Now on to animating a single page. Select the left vertex of the page. Move to frame 30
and activate the"Animate button (no image this time around ;-)). Now we'll see one of the nice things R3 has made possible: animating single vertices in a spline was still quite a task in R2.5.
Move the vertex to the opposite spot on the opposite half of the book. The small animated GIF up above illustrates that process. It also shows You that this process alone doesn't create a correct turning over effect. To do this, go to frame 15, and move the vertex over the center of the book in such a way, that it moves in a nicely curved fashion. If You take a look at the animation at this point, You will conclude that the middle of the page is still a bit wrong. The spline doesn't take the right form at the end of the animation, as the "middle" vertex hasn't been animated yet.
With that in Your mind; select the middle vertex and have a look at the handle to the upper-left, which is responsible for this aberration. It's pushing the spline off course. To correct the spline, it should be following the blue arrow.
And now on to something which is really new to R3: even handles can be animated. You could try to move the handle to the opposite side manually. But using that method, You would never get to the exact position needed to make the page (that is, the spline) fit to the mirrored counterpart of the book. You can't use transform type-ins, rotating the vertex is also imprecise... But You can scale it. Make sure that the vertex in the middle of the book is selected (that You're on frame 30, and that the Animate button is activated!), and then activate the Scale tool "select and non-uniform scale". When You right-click on the tool
Look at the animation in the front viewport. The spline now looks like a page turning over. You might need to set additional key frames for the other vertex between frames 0-15 and 15-30, to make the animation of the page turning over even smoother. The animation should then look somewhat like this one.
If You now go back to the Extrude modifier in the modifier stack, your spline will be made into a real page of a book, which at the moment, though, only has one side (the back is transparent). Correcting this is the next step, texturing:Open the Material Editor
and pick a material sphere. Click on Type (currently "Standard") and choose "Double Sided". The query that pops up when You can simply be affirmed. You now have a double sided material, which is made up out of two separate materials. This way, You can apply different materials to the front and back sides of the page. Apply this material to the page, by selecting the page, and clicking the "Apply to selection" button
. Now You will see the whole page (front and back) in the perspective view.
Look at the animation again: the page is turning over a little too rigidly. To change that, I have created a sphere in the middle of the book, as depicted in the image to the left. The number of segments in the sphere is set to 8, as it doesn't really need to be perfectly round.
Right-click on the sphere and choose "Properties" from the menu. De-activate the "Renderable" checkbox in the "Rendering Control" group. There sphere is still visible in the viewports, but won't be shown in the final render(and doesn't cast any shadows either).
Select the page again, and go to the modify panel
Now add a "Mesh Smooth" modifier, which subdivides your entire page even further (in case You think that the number of segments in Your page suffices, You can leave the Mesh Smooth out).
Now for another modifier: Under "More", locate and choose the "Volume Select"modifier, and choose in the "parameter" rollout, under "Stack Selection Level" for the "Vertex" option. Activate the "Select By: Mesh Object" option somewhat further down. Right below it is a button with the title "None". Click it, and pick the sphere we made earlier. You should now see in the viewport, how the vertices of the pages that are inside the sphere are being selected.
Remaining in the "Volume Select"modifier, scroll further down to the rollout entitled "Soft Selection". Change the falloff value of the soft selection to such an extent that the last 2 or 4 vertices in the middle of the book remain unchanged (i.e. blue), as shown in the image to the side. These "Soft Selections" are a new feature in R3, which isn't only available in the Volume Select modifier, but also in other modifier (e.g. Edit Mesh). Flags waving in the wind on one side and being attached to a pole on one side, are no problem anymore using these...Next, add a "Push" modifier. A value of -20 was sufficient to make a believable effect of wind resistance on the page in my scene. Play around a little with this value, until You're satisfied with the results.
And lastly, add a noise modifier. It will bring a little randomness to the whole. Here I used values of around 40 for the X, Y and Z axes. You might want to play around a bit with the scale of the noise, to get the desired effect.
The settings for the last 3 modifiers are pretty specific and can be changes as You please. The higher the "Push"-value, the wider the page will bulge as it is turned over. This makes it seem a little more soft, cloth-like even. Eventually it will be pushed out so strong, that part of the page will end up inside one of the two halves of the book. Should this be the case, You should change the falloff of the Volume Select, or move/scale down the sphere. There are so many factors playing in this effect, that I can't discuss them all in this tutorial. So just try various settings until You a result somewhat like this one.
If You now copy this single page two times, move the key frames for each 10 frames behind the other, and loop the animation (further explained in this tutorial); You will have a wonderful book with turning pages. Add a little materials, a few lights and whatever else is supposed to go with a book, done....
I have textured the book in the example file a little. It might be a little unpretty (just slapped on a quick diffuse map), but it is only meant to teach You how to use the Double Sided material. For each of the three animated pages there's a double sided material, each with two separate sides. The two halves of the book, from which the pages will turn over from/on to, have an animated texture assigned to them. For example, on the left half of the book, page X can be seen up to the moment that page X actually turns over. The texture then quickly changes to page Y, which will remain visible until page Y actually turns over. Got it ?! Simply have a look at the example scene to see it. So-called *.IFL files are responsible for the animated textures. You can open and view them with a normal text editor. If You do, it should become clear to You how these IFL-files work.
One last thing: looking at the final result, I am still fairly unsatisfied with it. The pages are turning over a little too slowly for my liking. The book halves could have been modeled and textured better, etc. etc...
So if any one of You creates something better than this, please write me an e-mail. I'd be interested in any avi or mpeg, no matter how small.