I'm creating a program in which a circle bounces around the inside of a larger circle. I have figured out how to calculate when and where the circles collide but not how to calculate the resulting vector on the bouncing circle that should be applied. ANY help would be greatly appreciated.
code below or in the web editor.
let pos, vel, acc;
function setup() {
createCanvas(400, 400);
pos = createVector(width / 2 + 20, height / 2 - 10); //inital position of ball
vel = createVector(0, 0.5); //inital velocity
acc = createVector(0.1, 0.1); //inital acc
}
function draw() {
background(220);
fill(255)
//vel.add(acc); //acceleration disabled due to testing
pos.add(vel); //adds velocity to the position
ellipse(pos.x, pos.y, 20); //draws the ball
noFill();
circle(width / 2, height / 2, 100); //draws the main ball (border)
if (dist(pos.x, pos.y, width / 2, height / 2) >= 50 - 10) { //if the ball hits the circle
theta = atan2(pos.y - height / 2, pos.x - width / 2);
pX = 50 * cos(theta) + width / 2;
pY = height / 2 + 50 * sin(theta);
POI = createVector(pX, pY); //point of intersection vector
fill(255, 0, 0);
circle(pX, pY, 2);
//a vector that when applied, *should* bounce the circle back
oppositeForceVector = p5.Vector.sub(POI, (width / 2, height / 2));
vel.add(oppositeForceVector);
vel.limit(1);
}
}<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.4.0/p5.js"></script>let pos, vel, acc;
function setup() {
createCanvas(400, 400);
pos = createVector(width / 2 + 20, height / 2 - 10); //inital position of ball
vel = createVector(0, 0.5); //inital velocity
acc = createVector(0, 0.1); //inital acc
}
function draw() {
background(220);
fill(255)
vel.add(acc); //acceleration disabled due to testing
pos.add(vel); //adds velocity to the position
ellipse(pos.x, pos.y, 20); //draws the ball
noFill();
circle(width / 2, height / 2, 100); //draws the main ball (border)
if (dist(pos.x, pos.y, width / 2, height / 2) >= 50 - 10) { //if the ball hits the circle
theta = atan2(pos.y - height / 2, pos.x - width / 2);
// Make our POI coordinates relative to the center of the circle
let pX = 50 * cos(theta);
let pY = 50 * sin(theta);
let POI = createVector(pX, pY); //point of intersection vector
// Find the tangent of the circle at the point of intersection
let tangent = POI.copy().rotate(PI / 2);
// Check the angle between or velocity, and the vector towards the POI
let angle = vel.angleBetween(POI);
// Don't "collide" if the circle is already moving back towards the center
if (abs(angle) <= PI / 2) {
// When we collide, or velocity vector should be mirrored, if we were pointing
// outwards at a 45 degree angle, we should now be pointed inward at a 45
// degree angle
vel.rotate(vel.angleBetween(tangent) * 2);
}
fill(255, 0, 0);
// when we draw the point of collision, offset from the center of the circle
circle(pX + width / 2, pY + height / 2, 2);
}
}<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.4.0/p5.js"></script>