I’m making a 2d game, and I’ve been struggling a lot with 2d collision. I have code that seems to work fine except for corners. When an entity collides exactly with a corner it just end up going straight though.
I’ve been trying to fix for literally 3 weeks. Ive tried AI, I’ve tried documentation, yt tutorials (which is where i got the code i have now) but nothing seems to work for corners as well.
Here is my current code:
for (let i = 0; i < entityHitboxLength; i += 8) {
let entityX = entityHitboxes[i];
let entityY = entityHitboxes[i + 1];
let entityXW = entityHitboxes[i + 2];
let entityYH = entityHitboxes[i + 3];
let prevEntityX = entityHitboxes[i + 4];
let prevEntityY = entityHitboxes[i + 5];
let prevEntityXW = entityHitboxes[i + 6];
let prevEntityYH = entityHitboxes[i + 7];
if (
selfYH > entityY &&
selfY < entityYH &&
selfX < entityXW &&
selfXW > entityX
) {
if (selfYH >= entityY && prevSelfYH < prevEntityY) {
selfYH = entityY - 1;
selfY = entityY - 1 - height;
} else if (selfY <= entityYH && prevSelfY > prevEntityYH) {
selfY = entityYH + 1;
selfYH = entityYH + 1 + height;
}
else if (selfXW >= entityX && prevSelfXW < prevEntityX) {
selfXW = entityX - 1;
selfX = entityX - 1 - width;
} else if (selfX <= entityXW && prevSelfX > prevEntityXW) {
selfX = entityXW + 1;
selfXW = entityXW + 1 + width;
}
}
}
Here is the code documentation i used for this.
Pretty simple and it works fine for edges.
Ive also tried an AI generated approach like
if (
selfYH > entityY &&
selfY < entityYH &&
selfX < entityXW &&
selfXW > entityX
) {
// Calculate overlaps on both axes
const overlapY = Math.min(selfYH - entityY, entityYH - selfY);
const overlapX = Math.min(selfXW - entityX, entityXW - selfX);
// Resolve the smaller overlap first
if (overlapX < overlapY) {
// Resolve X-axis collision
if (selfXW >= entityX && prevSelfXW < prevEntityX) {
selfXW = entityX - 1;
selfX = entityX - 1 - width;
} else if (selfX <= entityXW && prevSelfX > prevEntityXW) {
selfX = entityXW + 1;
selfXW = entityXW + 1 + width;
}
} else {
// Resolve Y-axis collision
if (selfYH >= entityY && prevSelfYH < prevEntityY) {
selfYH = entityY - 1;
selfY = entityY - 1 - height;
} else if (selfY <= entityYH && prevSelfY > prevEntityYH) {
selfY = entityYH + 1;
selfYH = entityYH + 1 + height;
}
}
}
But this passes through even more than the one im using, even at corners still. Is there something wrong with this code? how can i make it work?
2
Answers
Whitouth seen understanding you code very very (some relevant parts are missing) I would think the first
if
statement seems to be the culpritbecause here you are checking for
>
/<
and not>=
/<=
, but in the innerif
statements you are checking for>=
/<=
. So I assume, this could be the source of the problem especially in the corner area.I hope this function will be useful…
This is a small representation of our rectangle:
We will take the “x” of point A with obj.getX(), the “y”, with *obj.*getY()**, the “x” of point B with obj.getX() + obj.getwidth() and the Y of point C with obj.getY() + obj.getHeigth().
Then we have the width of the rectangle, obj.getWidth() and the height obj.getHeigth().
Then the expression to know if there is a collision is: