Boxes against walls, against each other, and gone

2026-10-24, the pod-physics session.

The step-logged Gold race on Canyon (derived/physics/gold-canyon), whose boxes were used for these runs.

The cases no race had

In the recorded races no car hit a prop. Earlier, Canyon's boxes were moved into the cars' path, which covered a box being hit and rolling along the road. Three things were still missing: a box pushing another box, a box against a wall, and a box that falls out of the track.

All three can be set up without a car. Each prop has a flag that says it was hit and should move. Setting that flag under the emulator makes Gold move the prop on its own. Canyon's stack of four boxes was set moving, so the boxes knocked into each other. One box was set just off a wall, and another 20 units under the road.

The stacked boxes touched 78 times. When two touch, they also hand on what they rest on: the other box's ground face, or, if they meet at a slant, the contact's own normal, kept in a small record of its own. The box by the wall touched it with 12 of its points. The box under the road found no sector holding it and nothing below it, so the game took it off the list. The list closes up behind it, and the game's loop then skips the box that moved into its place, for that step only. The port does the same.

Every call matched: 143 box steps, 2,687 box pairs and 214 whole collision passes.

The damage record

The race display shows each car's damage as small icons and a car picture. That comes from a record per racer. Each part that is hit gets an entry with its icon, its level (up to two breaks), and where on the screen it goes. After a break, the levels at the front and at the rear are added up, and past three that half of the car picture changes to its damaged image. The port keeps the same record and leaves the drawing to the display. Its 25 updates under the emulator, with parts breaking, match.

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What is left in the physics has not happened in any run: the track's zones, a car put back after two and a half seconds upside down, and a point that lost its sector.