  Drawing a direct analogy with the well-studied vibration or elastic modes, we
introduce an object's fracture modes, which constitute its preferred or most
natural ways of breaking. We formulate a sparsified eigenvalue problem, which
we solve iteratively to obtain the n lowest-energy modes. These can be
precomputed for a given shape to obtain a prefracture pattern that can
substitute the state of the art for realtime applications at no runtime cost
but significantly greater realism. Furthermore, any realtime impact can be
projected onto our modes to obtain impact-dependent fracture patterns without
the need for any online crack propagation simulation. We not only introduce
this theoretically novel concept, but also show its fundamental and practical
superiority in a diverse set of examples and contexts.
