3D World’s question of the month

Rendering convincing water is a tricky job, but throw in animation or interaction with other objects and the task becomes exponentially more complex. While simulation tools such as Blender’s built-in fluid simulator can help, the bigger a simulation becomes, the more time and processing power it takes to complete. If you try to simulate on a really large scale, like an ocean, you are likely to run into long cycles of tweaking and testing.

Luckily, 3D is all about knowing how to fake effects, and Blender provides us with many tools to do this – even the fluid system does its own share of faking by using particle systems to create small water droplets. Instead of using a real simulation, we can use a Wave modifier to fake the motion of large waves; animated materials for the smaller waves; and careful lighting and material set-ups to improve the appearance of the water. By using a lattice for the large waves, we can tie the motion to both the surface of the water and any objects that float on it: in this case, a raft. To do this we’ll use Blender’s modifier stack and a bit of parenting magic.

Even faking presents trade-off decisions: displacement maps look better and more realistic than bump maps, but require more geometry and longer render times. Since we’re using a large surface, we’ll use bump maps only. If we were only rendering a still, displacement would have been the better choice. We can also debate the use of raytracing, but for this scene, the speed hit was moderate, and the improvement to the render substantial. If you’re following on a slower computer, you could experiment with raytracing turned off and a tweaked light set-up.

Finally, more effects can be added to enhance the animation: a particle system parented to the raft and animated at the right point in time gives a quick, cheap splash effect, and a soft body simulation on the flag gives the appearance of wind on the cloth. These effects are set up in the final .blend file in the support files, but space constraints prevent us from discussing them in detail.

The support files include scene files for various stages of the walkthrough, starting with initial.blend. If you get stuck at any point, just load them in. The file final.blend contains everything needed to render both the animation and the image above.

Click here to download the support files (54MB)