# Modified Circle Collision to Rectangles

I found the code someone posted of Circle Collision and was trying to modify it to be rectangles and it’s all working well besides the collision detection being slightly off between the two rectangles.

void checkCollision(Rect other) {

``````// Get distances between the balls components
PVector distanceVect = PVector.sub(other.position, position);

// Calculate magnitude of the vector separating the balls
float distanceVectMag = distanceVect.mag();

// Minimum distance before they are touching
float minDistance = p + other.widthr;

if (distanceVectMag < minDistance) {
float distanceCorrection = (minDistance-distanceVectMag)/2.0;
PVector d = distanceVect.copy();
PVector correctionVector = d.normalize().mult(distanceCorrection);
position.sub(correctionVector);

// get angle of distanceVect
// precalculate trig values
float sine = sin(theta);
float cosine = cos(theta);

/* bTemp will hold rotated ball positions. You
just need to worry about bTemp position*/
PVector[] bTemp = {
new PVector(), new PVector()
};

/* this ball's position is relative to the other
so you can use the vector between them (bVect) as the
reference point in the rotation expressions.
bTemp.position.x and bTemp.position.y will initialize
automatically to 0.0, which is what you want
since b will rotate around b */
bTemp.x  = cosine * distanceVect.x + sine * distanceVect.y;
bTemp.y  = cosine * distanceVect.y - sine * distanceVect.x;

// rotate Temporary velocities
PVector[] vTemp = {
new PVector(), new PVector()
};

vTemp.x  = cosine * velocity.x + sine * velocity.y;
vTemp.y  = cosine * velocity.y - sine * velocity.x;
vTemp.x  = cosine * other.velocity.x + sine * other.velocity.y;
vTemp.y  = cosine * other.velocity.y - sine * other.velocity.x;

/* Now that velocities are rotated, you can use 1D
conservation of momentum equations to calculate
the final velocity along the x-axis. */
PVector[] vFinal = {
new PVector(), new PVector()
};

// final rotated velocity for b
vFinal.x = ((m - other.m) * vTemp.x + 2 * other.m * vTemp.x) / (m + other.m);
vFinal.y = vTemp.y;

// final rotated velocity for b
vFinal.x = ((other.m - m) * vTemp.x + 2 * m * vTemp.x) / (m + other.m);
vFinal.y = vTemp.y;

// hack to avoid clumping
bTemp.x += vFinal.x;
bTemp.x += vFinal.x;

/* Rotate ball positions and velocities back
Reverse signs in trig expressions to rotate
in the opposite direction */
// rotate balls
PVector[] bFinal = {
new PVector(), new PVector()
};

bFinal.x = cosine * bTemp.x - sine * bTemp.y;
bFinal.y = cosine * bTemp.y + sine * bTemp.x;
bFinal.x = cosine * bTemp.x - sine * bTemp.y;
bFinal.y = cosine * bTemp.y + sine * bTemp.x;

// update balls to screen position
other.position.x = position.x + bFinal.x;
other.position.y = position.y + bFinal.y;

// update velocities
velocity.x = cosine * vFinal.x - sine * vFinal.y;
velocity.y = cosine * vFinal.y + sine * vFinal.x;
other.velocity.x = cosine * vFinal.x - sine * vFinal.y;
other.velocity.y = cosine * vFinal.y + sine * vFinal.x;
}
``````

}

void display() {
noStroke();
fill(204);
rect(position.x, position.y, heightr, widthr);
}
}

Not sure how to post this correctly, but would greatly appreciate any help.

Hi,

To format your code, press `Ctrl+T` in the Processing IDE code editor and use the `</>` button when you edit a message on the forum.

I think you need to check this link :