Andres de Mingo give some insights into the making of this nice video, specially he explain how the castle was destroyed using Pulldownit plugin in 3d Max.
Modeling the Environment
For modeling the terrain I started with a high tessellated plane, in order to create hills and valleys I used the soft selection tool to raise different areas, finally applying a noise modifier to get a rough look on the surface. The Lake is done with another large plane with an animated displacement, and of course a water-like blend material for rendering it translucent. I populated the terrain with some trees, I used a little MCG scheme to place the trees in groups and changing ramdomly its size and number of branches so they didn’t look the same, MCG is a great tool for scattering objects ramdomly over a terrain.
Modeling the Dragon
Strictly speaking I modeled a Wyvern, this is a kind of Dragon without arms, it was modeled in several stages. First I did was a raw low poly version of it using just edit poly and turbo smooth in 3D Max, once I was happy with the result, unwrapped it and sent it to ZBrush for modeling the HiRes shape, I did it in two separate layers, one for the dragon body and another for the independent parts: claws, horns, teeth and thorns. I added also surface details to the body like wrinkles and scales, finally I applied a projection mapping to texture the model. I reduced the poly count of the model by passing some of the detail to a displacement map and send it back to 3d Max where I added a SSS shader to get a translucent look on the wings, finally I built a basic rig with bones so I could animate it later.
Animating the Dragon
First I had to drive the overall trajectory of the dragon towards the castle, for this I used a dummy and linking the Dragon skeleton as child of it, then I did the dummy to approach the castle in a smooth way, from side to side, like the flight of a seagull. In order to refine the motion, I edited the dummy trajectory in Motion>Trajectories>Sub-Object>Keys, in this way I was able to handle it as a spline, displacing the keys in a smooth way. For beating the wings and leaning its body I did a classic “Pose to pose” animation while it was approaching the castle, finally to get a cloth-like feeling of the wings I added a Flex modifier in the rear part of them.
Impact with the Stone
The stones thrown from the catapult are modeled as simple spheres with turbosmooth and a noise modifier to add roughness. The stones were animated so two of them almost collide with the dragon body, and the last one impact its head.
Making the third stone breaking when colliding with the dragon was very easy using Pulldownit, Esteban Cuesta shows it in this great video tutorial,
When playing the simulation the stone got broken perfectly when colliding with the dragon, finally I just added some jagginess to the fragments to improve the look of the flying fragments.
Destroying the Castle
The castle model was purchased on Internet, it looked very nice but when shattering the tower with Pulldownit, I got strange artifacts on the arcs, checking the model I found that it had several open edges, adding a cap holes modifier fixed the issues but made it completely solid and I wanted the tower to be holed inside, so I had to edit the mesh and adding a cylindrical wall on the inside, then applying a cap holes I got the holed solid shape that I wanted. I created a fracture body for the tower and set the dragon as kinematic with animated mesh to collide with it, in place of including the rest of the castle as static in dynamics I made some boxes and cylinders around it to act as barriers in dynamics to save computation time.
I destroyed also the roof of the tower below and the front porch, I did it in second step after baking keys for the fragments of the tower, I hadn’t any trouble to shatter those parts. For the few fragments falling into the pit in front of the Castle, I added a simple ripple effect to create some waves on the water when the fragments touched the water plane.
This project was pretty complex for just one person, lots of modeling and animating the dragon took time aswell, but I enjoyed doing it, and Pulldownit plugin made the destruction work easy and funny.