Computer Graphics & Visualization @ufrj.br
Published
Edited
Aug 4, 2022
Importers
18 stars
Canvas primerCanvas primer IISVG IntroMinimal WebGL ProgramWebGL primer with reglShadertoy style drawingTransformation demoModelview DemoModel, View and Projection DemoWebGL CubeCatmull Clark SubdivisionThree.js basicsPhong Illumination modelHalf-edge data structureIterated Function SystemsRaytracingTextured sphereEnvironment mappingPhysical animation with shape matchingShape matching2D GJK and EPA algorithmsOmohundro balltree construction algorithmsPlatonic Solids PlaygroundElliptic billiards 3-periodics in space-time3D LabyrinthBrush drawingBump mappingFractal TerrainModel viewerKeyframe animationTextured planeSimple Adaptive Mosaic EffectsWallpaper GroupsRay marchingVolume rendering with slice compositingDisplaying 3D RBFs with ray marchingFunções 2D úteisGPU-IO3D Apollonian Sphere PackingsCircle inversion fractalsApollonian gasket construction by inversionSmooth PolygonDocument image segmentationB-SplinesStencil bufferNoise LoopsSimplex noise exerciserDeformation with RBFsRandom shapes in a gridHobby curvesLane-Riesenfeld subdivision
Random space-filling curves
drawPath(ham, 10, 0.75)
function gridSpanningTree(ncols, nrows) {
const grid = new Array(ncols * nrows);
const col = (i) => i % ncols;
const row = (i) => ~~(i / ncols);
const index = (col, row) => row * ncols + col;
const edges = [];
const visit = (k) => {
grid[k] = true;
const [i, j] = [col(k), row(k)];
const neighbors = [];
if (i > 0) neighbors.push(k - 1);
if (j > 0) neighbors.push(k - ncols);
if (i + 1 < ncols) neighbors.push(k + 1);
if (j + 1 < nrows) neighbors.push(k + ncols);
d3.shuffle(neighbors);
for (let n of neighbors) {
if (!grid[n]) {
edges.push([k, n]);
visit(n);
}
}
};
visit(~~(Math.random() * ncols * nrows));
const connect = d3
.range(nrows * ncols)
.map((i) => ({ left: false, right: false, up: false, down: false }));
for (let [i, j] of edges) {
if (i > j) [i, j] = [j, i];
if (row(i) == row(j)) {
connect[i].right = connect[j].left = true;
} else {
connect[i].down = connect[j].up = true;
}
}
return { nrows, ncols, row, col, edges, connect };
}
st = {
randomize;
return gridSpanningTree(30, 20);
}
drawGraph = (st, cellSize = 10) => {
const { nrows, ncols, row, col, edges } = st;
const x = (i) => (col(i) + 0.5) * cellSize + 0.5;
const y = (i) => (row(i) + 0.5) * cellSize + 0.5;
const canvas = DOM.canvas(cellSize * ncols, cellSize * nrows);
const ctx = canvas.getContext("2d");
ctx.fillStyle = "#eee";
ctx.fillRect(0, 0, cellSize * ncols, cellSize * nrows);
ctx.strokeStyle = "black";
ctx.beginPath();
for (let [i, j] of edges) {
ctx.moveTo(x(i), y(i));
ctx.lineTo(x(j), y(j));
}
ctx.stroke();
return canvas;
}
drawGraph(st)
hamiltonianFromSpanningTree = (st) => {
const { nrows, ncols, row, col, edges, connect } = st;
const nrows2 = 2 * nrows;
const ncols2 = 2 * ncols;
const edges2 = [];
const grid2 = new Array(nrows2 * ncols2);
const index2 = (i, dcol, drow) =>
(row(i) * 2 + drow) * ncols2 + col(i) * 2 + dcol;
const col2 = (i) => i % ncols2;
const row2 = (i) => ~~(i / ncols2);
connect.forEach((cell, i) => {
let { left, right, up, down } = cell;
if (right) {
edges2.push([index2(i, 1, 0), index2(i, 2, 0)]);
edges2.push([index2(i, 1, 1), index2(i, 2, 1)]);
} else {
edges2.push([index2(i, 1, 0), index2(i, 1, 1)]);
}
if (!left) {
edges2.push([index2(i, 0, 0), index2(i, 0, 1)]);
}
if (down) {
edges2.push([index2(i, 0, 1), index2(i, 0, 2)]);
edges2.push([index2(i, 1, 1), index2(i, 1, 2)]);
} else {
edges2.push([index2(i, 0, 1), index2(i, 1, 1)]);
}
if (!up) {
edges2.push([index2(i, 0, 0), index2(i, 1, 0)]);
}
});
const link = d3.range(ncols2 * nrows2).map((x) => []);
for (let [i, j] of edges2) {
link[i].push(j);
link[j].push(i);
}
let j = 0;
const path = [];
const visited = [];
for (let k = edges2.length; k > 0; k--) {
path.push(j);
visited[j] = true;
j = visited[link[j][0]] ? link[j][1] : link[j][0];
}
return {
nrows: nrows2,
ncols: ncols2,
col: col2,
row: row2,
edges: edges2,
path
};
}
ham = hamiltonianFromSpanningTree(st)
drawGraph(ham)
drawPath = (ham, cellSize = 10, thick = 0.5) => {
const { nrows, ncols, row, col, path } = ham;
const x = (i) => (col(i) + 0.5) * cellSize + 0.5;
const y = (i) => (row(i) + 0.5) * cellSize + 0.5;
const canvas = DOM.canvas(cellSize * ncols, cellSize * nrows);
const ctx = canvas.getContext("2d");
ctx.strokeStyle = "black";
ctx.lineJoin = "round";
ctx.lineWidth = cellSize * thick;
ctx.beginPath();
for (let i of path) {
ctx.lineTo(x(i), y(i));
}
ctx.closePath();
ctx.stroke();
return canvas;
}
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