Move a many-jointed tentacle, neck or crane arm to a target without stretching

When a creature has more than two joints, the limb formula no longer applies, and moving each joint by hand makes the chain stretch, shrink or tie in knots. Here is a way that keeps every piece the same length, keeps the base in place and handles targets that are too far.

Why this works

Pulling each joint back onto the exact distance from its neighbour keeps every piece the same length by construction, so errors cannot add up. Sweeping from the tip to the base and back lets the end reach the goal while the base stays where it is.

When not to use it

Wrong when the body must bend in a fixed way, like a spine with strict joint limits, or when it is only two parts, where the direct formula is exact and cheaper. Use that, or keyed clips, when the shape matters more than reaching.

In the full entry

• What to build, step by step
• Starting values and the reason for each
• 3 common mistakes and the fix
• 36 lines of example code with 4 checks that pass
• How your AI shows you that it works

Say this to your AI

Use the Spielerando entry "Move a many-jointed tentacle, neck or crane arm to a target without stretching" (read_entry tentacle-or-neck-chain-that-reaches-and-keeps-its-length) in my game. Build it step by step, and show me how you checked that it works.

Or skip this and connect the MCP: your AI then finds all of this by itself.Connect the MCP