🪡 Needle in a Haystack

About this simulation

"Finding a needle in a haystack" is the classic shorthand for an unstructured search problem: one target hidden among a huge number of near-identical distractors, with no shortcut but to check candidates. This simulation renders that literally — thousands of hay strands piled into a mound, one or more metallic needles hidden among them — and turns the search itself into the interaction.

How it works

• Every click raycasts into the pile and returns a 3D point on its surface, dropping a coloured search pin there.
• The proximity bar and the pin colour report how close that point is to the nearest unfound needle — hotter (red) means closer, colder (blue) means farther. Sound on: pitch rises as you get warmer.
• Clicking within a needle's hit radius finds it; with more than one needle, find them all to finish the search.
• With no proximity feedback, an unstructured search like this needs on average N/2 checks for N candidates — the same reason linear search is O(n). The proximity bar turns it into an informed search instead, closer to how a real search algorithm prunes the space.

Controls

• Haystack size — Small / Medium / Large; a bigger pile means a smaller relative hit radius per needle.
• Straw density — how many hay strands render, purely visual/performance (does not change difficulty).
• Needles — search for 1 to 3 hidden needles at once.
• Reveal needle(s) — highlights every needle's location for demonstration (does not count as a find).
• Search pins — toggles the coloured markers left at each click.
• Sound — a hot/cold beep on each search, and a chime when you find a needle.
• Auto-rotate — slowly spins the camera around the haystack.
• ↺ New Haystack — regenerates the pile and hides new needles. Drag to rotate, scroll to zoom.