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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

` ````
<div id="canvasContainer" style="width:100vw;height:100vh"><canvas id="canvas" width="320" height="320"></canvas></div>
```

` ````
class App {
constructor(div) {
this.div = div;
this.canvas = document.getElementById("canvas");
this.ctx = canvas.getContext('2d');
this.dirty = true;
this.prev = +new Date();
this.prevPos = [0, 0];
this.resize();
window.addEventListener('resize', () => this.resize(), false);
this.canvas.addEventListener("mousedown", (event) => {
this.prevPos = App.getmousePos(event)
this.touchdown(...this.prevPos);
event.preventDefault();
});
this.canvas.addEventListener("mousemove", (event) => {
let curPos = App.getmousePos(event);
this.touchmove(...curPos, curPos[0]-this.prevPos[0], curPos[1]-this.prevPos[1]);
this.prevPos = curPos;
event.preventDefault();
});
this.canvas.addEventListener("mouseup", (event) => {
this.touchup(...App.getmousePos(event));
event.preventDefault();
});
this.canvas.addEventListener("touchstart", (event) => {
this.prevPos = App.getmousePos(event)
this.touchdown(...this.prevPos);
event.preventDefault();
});
this.canvas.addEventListener("touchmove", (event) => {
let curPos = App.getmousePos(event);
this.touchmove(...curPos, curPos[0]-this.prevPos[0], curPos[1]-this.prevPos[1]);
this.prevPos = curPos;
event.preventDefault();
});
this.canvas.addEventListener("touchend", (event) => {
this.touchup(...App.getmousePos(event));
event.preventDefault();
});
}
resize() {
this.canvas.width = this.div.clientWidth;
this.canvas.height = this.div.clientHeight;
this.dirty = true;
}
loop() {
let now = +new Date();
let dt = now - this.prev;
this.prev = now;
this.update(dt/1000)
if (this.dirty)
this.draw(this.ctx);
window.requestAnimationFrame(() => this.loop());
}
update(dt) {}
draw(ctx) {
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.rect(0, 0, 100, 100);
ctx.fill();
}
touchdown(x, y) { console.log("down", x, y); }
touchmove(x, y) {}
touchup(x, y) {}
static getmousePos(event) {
if (event.changedTouches) {
return [event.changedTouches[0].pageX, event.changedTouches[0].pageY];
}
else {
var rect = event.target.getBoundingClientRect();
return [event.clientX- rect.left, event.clientY - rect.top];
}
}
}
function pointInCircle(x, y, cx, cy, r) {
let [vx, vy] = [x - cx, y - cy];
return vx*vx+vy*vy < r*r;
}
function pointOnLine(x, y, p1x, p1y, p2x, p2y) {
let [v1x, v1y] = [x - p1x, y - p1y];
let [v2x, v2y] = [p2x - p1x, p2y - p1y];
// Get scalar projection
let t = (v1x * v2x + v1y * v2y) / (v2x * v2x + v2y * v2y);
// Check if within boundaries
if (t < 0 || t > 1)
return false;
// Calculate the projected point
let [px, py] = [p1x + t * v2x, p1y + t * v2y];
// Calculate position and check if close enough
return pointInCircle(x, y, px, py, 5) ? [px, py] : false;
}
function pointInPolygon(x, y, points) {
let [x1, y1] = [points[points.length-2], points[points.length-1]];
let [x2, y2] = [points[0], points[1]];
let inside = false;
// For every edge, check for an intersection
for (let i = 0; i < points.length; i+=2) {
if (((y1 >= y) != (y2 >= y)) && (x < (x2 - x1) * (y - y1) / (y2 - y1) + x1)) {
inside = !inside;
}
[x1, y1] = [x2, y2];
[x2, y2] = [points[i+2], points[i+3]];
}
return inside;
}
function projectPolygon(points, x, y, nx, ny) {
let min = (points[0]-x)*nx+(points[1]-y)*ny;
let max = min;
let s;
for (let i = 2; i < points.length; i+=2) {
s = (points[i]-x)*nx+(points[i+1]-y)*ny;
if (s < min) min = s;
if (s > max) max = s;
}
return [min, max];
}
function polygonCollidesWith(points1, points2) {
// We project both polygons on all normals of polygon 1
let [x1, y1] = [points1[points1.length-2], points1[points1.length-1]];
let [x2, y2] = [points1[0], points1[1]];
let nx, ny, min1, max1, min2, max2;
// For every edge of points1
for (let i = 0; i < points1.length; i+=2) {
// Get edge normal by rotating the vector [x2-x1, y2-y1] by 90 degrees
[nx, ny] = [y2-y1, x1-x2];
// Project both polygons onto the normal
[min1, max1] = projectPolygon(points1, x2, y1, nx, ny);
[min2, max2] = projectPolygon(points2, x2, y1, nx, ny);
// If there is no overlap between the ranges, there is no collision
if (max1 <= min2 || min1 >= max2)
return false;
[x1, y1] = [x2, y2];
[x2, y2] = [points1[i+2], points1[i+3]];
}
return true;
}
function polygonsCollide(points1, points2) {
return polygonCollidesWith(points1, points2) && polygonCollidesWith(points2, points1);
}
function polygonCollidesWithV(points1, points2) {
// We project both polygons on all normals of polygon 1
let [x1, y1] = [points1[points1.length-2], points1[points1.length-1]];
let [x2, y2] = [points1[0], points1[1]];
let nx, ny, min1, max1, min2, max2;
let overlap, smallestOverlap, length, overlapX, overlapY;
// For every edge of points1
for (let i = 0; i < points1.length; i+=2) {
// Get edge normal by rotating the vector [x2-x1, y2-y1] by 90 degrees
[nx, ny] = [y2-y1, x1-x2];
// Project both polygons onto the normal
[min1, max1] = projectPolygon(points1, x2, y1, nx, ny);
[min2, max2] = projectPolygon(points2, x2, y1, nx, ny);
// If there is no overlap between the ranges, there is no collision
if (max1 <= min2 || min1 >= max2)
return false;
overlap = Math.min(max1, max2) - Math.max(min1, min2);
// Our scalar projection wasn't scaled yet
length = nx*nx+ny*ny;
overlap /= length;
// And we need to take the length of the vector into account for the overlap length
length = Math.sqrt(length);
// Record smallest overlap
if (!smallestOverlap || overlap * length < smallestOverlap) {
smallestOverlap = overlap * length;
overlapX = nx*overlap;
overlapY = ny*overlap;
}
[x1, y1] = [x2, y2];
[x2, y2] = [points1[i+2], points1[i+3]];
}
return [smallestOverlap, overlapX, overlapY];
}
function polygonsCollideV(points1, points2) {
let overlap1 = polygonCollidesWithV(points1, points2);
let overlap2 = polygonCollidesWithV(points2, points1);
if (overlap1 && overlap2) {
let overlap = overlap1[0] < overlap2[0] ? overlap1 : overlap2;
return overlap;
}
else
return false;
}
function polygonCenter(points) {
let [centerX, centerY] = [points[0], points[1]];
for (let i=2; i < points.length; i+=2) {
centerX += points[i];
centerY += points[i+1];
}
centerX /= points.length / 2;
centerY /= points.length / 2;
return [centerX, centerY];
}
class GameApp extends App {
constructor(div) {
super(div);
let [cx, cy] = [canvas.width*0.5, canvas.height*0.5];
this.polygons = [[cx, cy-120, cx+120, cy, cx, cy+120, cx-120, cy],
[cx-120, cy-120, cx+120, cy-120, cx+120, cy+120, cx-120, cy+120]];
this.grab = false;
this.loop();
}
update(dt) {
}
draw(ctx) {
ctx.clearRect(0, 0, canvas.width, canvas.height);
// Polygons
ctx.strokeStyle = "blue";
for (let points of this.polygons) {
ctx.beginPath();
ctx.moveTo(points[0], points[1]);
for (let i=2; i < points.length; i+=2)
ctx.lineTo(points[i], points[i+1]);
ctx.closePath();
ctx.stroke();
}
// Vertices
ctx.fillStyle = "blue";
for (let points of this.polygons) {
for (let i=0; i < points.length; i+=2) {
ctx.beginPath();
ctx.arc(points[i], points[i+1], 5, 0, 2 * Math.PI, false);
ctx.fill();
}
}
ctx.fillStyle = "black";
let overlap = polygonsCollideV(this.polygons[0], this.polygons[1]);
if (overlap) {
let [distance, vx, vy] = overlap;
ctx.fillText(`Colliding with ${distance}`, 10, 10);
let [center1X, center1Y] = polygonCenter(this.polygons[0]);
let [center2X, center2Y] = polygonCenter(this.polygons[1]);
let [px, py] = [center1X-center2X, center1Y-center2Y];
if (vx*px+vy*py < 0) {
vx = -vx;
vy = -vy;
}
ctx.strokeStyle = "green";
ctx.beginPath();
ctx.moveTo(center2X, center2Y);
ctx.lineTo(center2X+px, center2Y+py);
ctx.stroke();
ctx.strokeStyle = "red";
ctx.beginPath();
ctx.moveTo(center1X, center1Y);
ctx.lineTo(center1X+vx, center1Y+vy);
ctx.stroke();
}
else
ctx.fillText("Not colliding", 10, 10);
const url = "www.fromatogra.com";
ctx.fillText(url, (canvas.width-ctx.measureText(url).width)*0.5, 10);
this.dirty = false;
}
touchdown(x, y) {
this.grab = true;
for (let points of this.polygons) {
for (let i=0; i < points.length; i+=2) {
if (pointInCircle(x, y, points[i], points[i+1], 25)) {
this.grabInfo = [points, "vertex", i];
return;
}
}
}
for (let points of this.polygons) {
let segment = points.length-2;
let intersection = pointOnLine(x, y, points[segment], points[segment+1], points[0], points[1]);
for (let i=0; i < points.length; i+=2) {
if (intersection) {
let [px, py] = intersection;
console.log(`segment ${segment} hit at ${px}, ${py}`);
this.grabInfo = [points, "edge", segment];
return;
}
segment = i;
intersection = pointOnLine(x, y, points[i], points[i+1], points[i+2], points[i+3]);
}
}
for (let points of this.polygons) {
if (pointInPolygon(x, y, points)) {
console.log(`polygon hit`);
this.grabInfo = [points, "polygon"];
return;
}
}
this.grabInfo = null;
}
touchmove(x,y, dx, dy) {
if (!this.grab)
return;
if (this.grabInfo != null) {
let [points, type, index] = this.grabInfo;
if (type == "vertex") {
points[index] += dx;
points[index+1] += dy;
}
else if (type == "edge") {
points[index] += dx;
points[index+1] += dy;
if (index+2 < points.length) {
points[index+2] += dx;
points[index+3] += dy;
}
else {
points[0] += dx;
points[1] += dy;
}
}
else if (type = "polygon") {
for (let i=0; i < points.length; i+=2) {
points[i] += dx;
points[i+1] += dy;
}
}
this.dirty = true;
}
}
touchup(x, y) {
if (!this.grab)
return;
let overlap = polygonsCollideV(this.polygons[0], this.polygons[1]);
if (overlap) {
let [distance, vx, vy] = overlap;
let [center1X, center1Y] = polygonCenter(this.polygons[0]);
let [center2X, center2Y] = polygonCenter(this.polygons[1]);
let [px, py] = [center1X-center2X, center1Y-center2Y];
if (vx*px+vy*py < 0) {
vx = -vx;
vy = -vy;
}
let points = this.polygons[0];
for (let i=0; i < points.length; i+=2) {
points[i] += vx;
points[i+1] += vy;
}
this.dirty = true;
}
this.grab = false;
}
}
let app = new GameApp(document.getElementById("canvasContainer"));
```

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