This example demonstrates a collision-detection simulation using D3.js v4, displaying 1000 circles of varying sizes that repel each other while being pulled toward the center of a 960×960 canvas. The visualization uses `d3.forceSimulation` combined with `d3.forceCollide`, `d3.forceX`, and `d3.forceY` to compute particle positions, while rendering occurs via Canvas 2D API calls like `clearRect` and `context.arc`. The force-collision algorithm prevents overlaps by iterating collision checks twice per tick, and randomized radii from 4 to 18 pixels create the visual variety. All drawing is handled directly on the Canvas element rather than through SVG, producing a smooth real-time animation.