Collision & Physical Response

[jazz_e_bob]

I can't seem to get this to work properly. Here is my test file.

http://www.maybanana.com/pantzboi/images/collision.zip

What am I doing wrong here?

[makslane]

Has a small bug in collisions calculations.
I don't know when this happens

[jazz_e_bob]

Oh well!

No matter then.

I'll go back to my circle collision script. It has much improved since you implemented local variables. The only downside is that it only works with circular objects.

All the best.

/* actor collides with another actor (collide) */
collisionDistance = radius + collide.radius;
actualDistance = distance (x, y, collide.x, collide.y);
collNormalAngle = atan2(collide.y - y, collide.x - x);
/* position exactly touching - no intersection */
moveDist1 = (collisionDistance - actualDistance) * (collide.mass/(mass + collide.mass));
moveDist2 = (collisionDistance - actualDistance) * (mass/(mass + collide.mass));
x = x + moveDist1 * cos(collNormalAngle + 180);
y = y + moveDist1 * sin(collNormalAngle + 180);
/* collision response */
nX = cos(collNormalAngle);
nY = sin(collNormalAngle);
a1 = xvelocity * nX + yvelocity * nY;
a2 = collide.xvelocity * nX + collide.yvelocity * nY;
optimisedP = ( 2 * (a1 - a2)) / ( mass + collide.mass);
/* now find out the resultant vectors */
xvelocity = xvelocity - (optimisedP * collide.mass * nX);
yvelocity = yvelocity - (optimisedP * collide.mass * nY);
collide.xvelocity = collide.xvelocity + (optimisedP * mass * nX);
collide.yvelocity = collide.yvelocity + (optimisedP + mass * nY);

[jazz_e_bob]

Whoops. Found a bug in my code. Here is the new one.


/* actor collides with another actor (collide) */
collisionDistance = radius + collide.radius;
actualDistance = distance (x, y, collide.x, collide.y);
collNormalAngle = atan2(collide.y - y, collide.x - x);
/* position exactly touching - no intersection */
moveDist1 = (collisionDistance - actualDistance) * (collide.mass/(mass + collide.mass));
moveDist2 = (collisionDistance - actualDistance) * (mass/(mass + collide.mass));
x = x + moveDist1 * cos(collNormalAngle + 180);
y = y + moveDist1 * sin(collNormalAngle + 180);
/* collision response */
nX = cos(collNormalAngle);
nY = sin(collNormalAngle);
a1 = xvelocity * nX + yvelocity * nY;
a2 = collide.xvelocity * nX + collide.yvelocity * nY;
optimisedP = ( 2 * (a1 - a2)) / ( mass + collide.mass);
/* now find out the resultant vectors */
xvelocity = xvelocity - (optimisedP * collide.mass * nX);
yvelocity = yvelocity - (optimisedP * collide.mass * nY);
collide.xvelocity = collide.xvelocity + (optimisedP * mass * nX);
collide.yvelocity = collide.yvelocity + (optimisedP * mass * nY);

[jazz_e_bob]

Latest Version:

double massCollider = 10;
double massCollidee = 10;
double nX;
double nY;
double a1;
double a2;
double optimisedP;
/* player has collided */
double collisionDistance = (width/2) + (collide.width/2);
double actualDistance = distance (x, y, collide.x, collide.y);
double collNormalAngle = atan2(collide.y - y, collide.x - x);
/* position exactly touching - no intersection */
double moveDist1 = (collisionDistance - actualDistance) * (massCollidee/(massCollider + massCollidee));
double moveDist2 = (collisionDistance - actualDistance) * (massCollider/(massCollider + massCollidee));
x = x + moveDist1 * cos(collNormalAngle + 180);
y = y + moveDist1 * sin(collNormalAngle + 180);
collide.x = collide.x + moveDist2 * cos(collNormalAngle + 180);
collide.y = collide.y + moveDist2 * sin(collNormalAngle + 180);
/* collision response */
nX = cos(collNormalAngle);
nY = sin(collNormalAngle);
a1 = xvelocity * nX + yvelocity * nY;
a2 = collide.xvelocity * nX + collide.yvelocity * nY;
optimisedP = ( 2 * (a1 - a2)) / ( massCollider + massCollidee);
/* now find out the resultant vectors */
xvelocity = xvelocity - (optimisedP * massCollidee * nX);
yvelocity = yvelocity - (optimisedP * massCollidee * nY);
collide.xvelocity = collide.xvelocity + (optimisedP * massCollider * nX);
collide.yvelocity = collide.yvelocity + (optimisedP * massCollider * nY);