You gave it a string for each frame
The tree is rebuilt every frame. For scenes of this scale, quadtree construction is fast enough to rebuild from scratch each frame, though larger simulations may benefit from incremental updates. Each particle queries its neighborhood for potential collisions, typically checking only 5 to 15 candidates instead of all 40. Red highlights indicate colliding pairs.
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圖像來源，BBC Chinese / Lok Lee
与此同时，另一款重要数码产品，手机也开始了更新换代。
Agar was first introduced into the laboratory in 1881. Since then, microbiologists have depended on agar to create strong jellies. When microorganisms are streaked or plated onto this jellied surface and incubated, individual cells multiply into distinct colonies that scientists can easily observe, select, and propagate for further experiments. Many of the most important findings in biological research of the last 150 years or so — including the discovery of the CRISPR/Cas9 gene-editing tool — have been enabled by agar.4 Agarose, a derivative of agar, is also essential in molecular biology techniques like gel electrophoresis, where its porous gel matrix separates DNA fragments by size, enabling researchers to analyze and isolate specific genetic sequences.