Computer Graphics & Visualization @ufrj.br
Published
Edited
Apr 23, 2022
5 forks
1 star
isoscelesDemo = {
const demo = html`<canvas width=500 height=500 style="border:1px solid gray">`;
const ctx = demo.getContext("2d");
const iso = [
[200, 300],
[300, 200]
];
const update = () => {
ctx.clearRect(0, 0, 500, 500);
ctx.fillStyle = ctx.strokeStyle = "black";
for (let p of iso) {
ctx.beginPath();
ctx.arc(...p, 5, 0, Math.PI * 2);
ctx.fill();
}
ctx.beginPath();
for (let p of isosceles(...iso)) {
ctx.lineTo(...p);
}
ctx.closePath();
ctx.stroke();
};
update();
let prevMouse = null;
const dragBase = (e) => {
let mouse = [e.offsetX, e.offsetY];
let [base, vtx] = iso;
let v = vec2.sub([], vtx, base);
let delta = vec2.sub([], mouse, prevMouse);
prevMouse = mouse;
vec2.add(base, base, delta);
vec2.add(vtx, base, v);
};
const dragVtx = (e) => {
let mouse = [e.offsetX, e.offsetY];
let [base, vtx] = iso;
let delta = vec2.sub([], mouse, prevMouse);
prevMouse = mouse;
vec2.add(vtx, vtx, delta);
};
demo.onmousedown = (e) => {
const mouse = [e.offsetX, e.offsetY];
prevMouse = mouse;
demo.onmousemove = null;
for (let i of [0, 1]) {
let p = iso[i];
let d = vec2.distance(mouse, p);
if (d <= 5) {
demo.onmousemove =
i == 0
? (e) => {
dragBase(e);
update();
}
: (e) => {
dragVtx(e);
update();
};
}
}
};
demo.onmouseup = () => {
demo.onmousemove = null;
};
return demo;
}
import { vec2 } from "@esperanc/funcoes-2d-uteis"
//
// Returns the 3 vertices of an isosceles triangle
// defined by the center point of its base and the
// opposite vertex
//
function isosceles(basePoint, oppositeVertex) {
const u = vec2.sub([], basePoint, oppositeVertex);
const v = [-u[1], u[0]];
const w = [u[1], -u[0]];
return [
oppositeVertex,
vec2.add([], basePoint, v),
vec2.add([], basePoint, w)
];
}
One platform to build and deploy the best data apps
Experiment and prototype by building visualizations in live JavaScript notebooks. Collaborate with your team and decide which concepts to build out.
Use Observable Framework to build data apps locally. Use data loaders to build in any language or library, including Python, SQL, and R.
Seamlessly deploy to Observable. Test before you ship, use automatic deploy-on-commit, and ensure your projects are always up-to-date.