2a:null 2b:["$","title",null,{"children":"Convex Polygon Incircle | Mike Bostock | Observable"}] 31:Te89,{ let circle = [NaN, NaN, 0]; const context = DOM.context2d(width, height); yield context.canvas; for (let i = 0, n = polygon.length - 1; i < n; ++i) { const pi0 = polygon[i], pi1 = polygon[i + 1]; for (let j = i + 1; j < n; ++j) { const pj0 = polygon[j], pj1 = polygon[j + 1]; for (let k = j + 1; k < n; ++k) { const pk0 = polygon[k], pk1 = polygon[k + 1]; context.clearRect(0, 0, width, height); const l0 = lineExtend(pi0, pi1); const l1 = lineExtend(pj0, pj1); const l2 = lineExtend(pk0, pk1); context.save(); context.beginPath(); context.moveTo(...l0[0]); context.lineTo(...l0[1]); context.moveTo(...l1[0]); context.lineTo(...l1[1]); context.moveTo(...l2[0]); context.lineTo(...l2[1]); context.setLineDash([3, 3]); context.strokeStyle = "#ccc"; context.stroke(); context.restore(); context.save(); context.beginPath(); context.moveTo(...polygon[0]); for (let l = 1; l < n; ++l) context.lineTo(...polygon[l]); context.closePath(); context.strokeStyle = "#ccc"; context.stroke(); context.restore(); const s0 = lineLineBisect(pi0, pi1, pj1, pj0); const s1 = lineLineBisect(pj0, pj1, pk1, pk0); if (!s0 || !s1) continue; // Parallel! const b0 = lineExtend(...s0); const b1 = lineExtend(...s1); context.save(); context.beginPath(); context.moveTo(...b0[0]); context.lineTo(...b0[1]); context.moveTo(...b1[0]); context.lineTo(...b1[1]); context.strokeStyle = "blue"; context.stroke(); context.restore(); if (circle[2] > 0) { const [cx, cy, cr] = circle; context.save(); context.beginPath(); context.moveTo(cx + cr, cy); context.arc(cx, cy, cr, 0, 2 * Math.PI); context.globalAlpha = 0.2; context.fill(); context.restore(); } const [x, y, r] = circleTangent(pi0, pi1, pj0, pj1, pk0, pk1); let contained = true; for (let l = 0; l < n; ++l) { if (l === i || l === j || l === k) continue; const d = pointLineDistance([x, y], polygon[l], polygon[l + 1]); if (d + 1e-6 < r) { contained = false; break; } } if (contained && r > circle[2]) circle = [x, y, r]; context.save(); context.beginPath(); context.moveTo(x + r, y); context.arc(x, y, r, 0, 2 * Math.PI); context.lineWidth = 1.5; context.strokeStyle = contained ? "black" : "red"; context.stroke(); context.restore(); context.save(); context.beginPath(); context.moveTo(...pi0); context.lineTo(...pi1); context.moveTo(...pj0); context.lineTo(...pj1); context.moveTo(...pk0); context.lineTo(...pk1); context.lineWidth = 1.5; context.stroke(); context.restore(); yield Promises.delay(1000, context.canvas); } } } context.clearRect(0, 0, width, height); context.save(); context.beginPath(); context.moveTo(...polygon[0]); for (let l = 1, n = polygon.length - 1; l < n; ++l) context.lineTo(...polygon[l]); context.closePath(); context.strokeStyle = "#ccc"; context.stroke(); context.restore(); const [cx, cy, cr] = circle; context.save(); context.beginPath(); context.moveTo(cx + cr, cy); context.arc(cx, cy, cr, 0, 2 * Math.PI); context.lineWidth = 1.5; context.strokeStyle = "#000"; context.stroke(); context.restore(); yield context.canvas; }32:[] 2e:{"id":"c91abc6d29206a66","slug":"convex-polygon-incircle","title":"Convex Polygon Incircle","thumbnail":"a744de390dfc649ce29e3c20f12a735c01bb7040488aa828f030b6ceb481fe6a","access_level":"public","create_time":"$D2018-05-26T21:53:39.878Z","update_time":"$D2018-10-28T18:24:13.716Z","view_time":null,"first_public_time":"$D2018-05-27T03:05:49.745Z","fork":{"id":"461de0e0ae9642fa","slug":"circle-tangent-to-three-lines","title":"Circle Tangent to Three Lines","owner":{"id":"8c2e47252fd4995c","login":"mbostock","name":"Mike Bostock"}},"stars":6,"starred":false,"owner":{"type":"team","id":"8c2e47252fd4995c","login":"mbostock","name":"Mike Bostock","avatar_url":"https://avatars-next.observableusercontent.com/7dbba99ced40bd5ab8013c99b1a11da61231bce321ba1148a9d16ad0f121550a","tier":"starter_2024"},"version":623,"publish_version":623,"role":null,"authored":false,"authors":[{"type":"individual","id":"074c414ad1d825f5","login":"mbostock","name":"Mike Bostock","avatar_url":"https://avatars-next.observableusercontent.com/7dbba99ced40bd5ab8013c99b1a11da61231bce321ba1148a9d16ad0f121550a","tier":null}],"members":[{"type":"individual","id":"074c414ad1d825f5","login":"mbostock","name":"Mike Bostock","avatar_url":"https://avatars-next.observableusercontent.com/7dbba99ced40bd5ab8013c99b1a11da61231bce321ba1148a9d16ad0f121550a","tier":null,"role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"subscribed":null,"forks":3,"collection":{"id":"6d94bdd16890def0","slug":"geometry","title":"Geometry","owner":{"id":"8c2e47252fd4995c","login":"mbostock","name":"Mike Bostock"}},"type":"notebook","body":{"title":"Convex Polygon Incircle","cells":[{"id":0,"value":"md`# Convex Polygon Incircle\n\nFor each set of three sides of a convex polygon, compute the [circle tangent to three lines](/@mbostock/circle-tangent-to-three-lines) and test whether this circle is contained by the polygon; the largest of the contained tangent circles is the largest inscribed circle.`","pinned":false,"hidden":false,"mode":"ojs"},{"id":529,"value":"viewof replay = html`