Looking into Object Relationships
It’s easy to take for granted how the things in our universe relate to one another. Our Earth relates to the Sun, orbiting it in perpetuity, drawn inward by gravity. The Earth’s own gravity pulls you toward its center while the solid ground pushes you, keeping your movements constrained to the planet’s surface as it spins through the cosmos. Magnets relate by attracting and repelling each other. Your pants stay on your legs when you walk around.
In the world of 3D animation, we can’t take such relationships for granted. If we don’t do the work of nature ourselves, bodies in space will not interact, things will fall apart and pass through solid matter, and characters’ pants will remain at a fixed point in space after their legs have walked away (this happens way more often than you’d think).
For this chapter, we will set aside most of what we’ve learned so far about animating objects directly...
