This demo is a fairly simple explanation of the principles behind the process, which involves the addition of a Collide Constraint to all the parts involved in the collision. To create the collision in this case, we are going to use an invisible HyperMatter panel as a collision object, and also use fixed object deformation for added comic effect.

Load the scene Dog and Pan.max (115K)

The scene shows a dog’s head, with HyperMatter already applied, and a keyframed frying pan, which will swing round and hit the dog full in the face. The frying pan has a HyperMatter block attached to it via a Follow Constraint. The block has also been ‘Set’ to maintain its shape during the collision. The block has been assigned a transparent material, so that it will not render.

The first thing we are going to do is apply a Collide Constraint to both the block and the front of the dog’s face. This will begin just before they impact, and last until the frying pan swings back out of the way. As collisions are very processor-intensive, we must make sure that the Constraint only lasts for the duration of the collision, as the extra calculations are wasted outside this range.

So we bring up a pre-set part named ‘Bump’, and apply the Collide Constraint to it, running from Frames 52 to 68.

Now we select the block object, and select the part ‘Exterior’. Now deselect all the points except the front faces, the side that will hit the dog. We name this part ‘Bump’ also, although you would probably need to give the parts more meaningful names in complicated scenes.

We apply a Collide Constraint to this part, and make sure it occupies the same collision domain and frame range as the dog’s collide part. The default procedure for HyperMatter will be to assign the next object a new collision domain, so set the domain for both objects to 1.

Now when we play the animation, we see that when the pan should collide with the dog, it actually passes through it, only slightly snagging the mesh. The reason for this is because the frying pan swings in so quickly, that the distance moved per frame is too great for the HyperMatter engine to evaluate the collision correctly. To fix this we must modify the Sampling Rate.

First, open the Sampling rollout in the Substance editor, and reset the Sampling option from Automatic to Manual. Now we open the Track View, and bring down the sampling track for the two objects. We enter two keys for each object, at Frames 48 and 52. We set the second key value to 15, so that the sampling rate increases dramatically as the collision approaches

Now when we hit Play, the collision is calculated correctly, and the head is knocked backwards with the impact. That’s fairly amusing, although it would be even funnier, if the head stayed where it was, and the face flattened out like Tom and Jerry’s do.

We select the part named ‘Back’ and apply a Fix Constraint, beginning at Frame 56. This will hold the head in position, forcing the face to compress against it under the force if the collision.

At this point, we can also apply the Set Constraint to the part ‘Front’, which contains all the points not included in the part ‘Back’. This effectively gives us two halves to the object, which are free to do separate things, but still behave as a whole. The Set Constraint will force the part to accept the deformed state it currently holds as permanent, at least whilst the Constraint is active, but still allow it some freedom of movement relative to the back of the head.

We do want the face to pop back out again, so we will set the Constraint to end at about Frame 125.

Now when we play the animation, we can see that the collision splats the face flat, and then the face pops out, performing realistic secondary wobbling, which would be virtually impossible to achieve using any other animation system.