SFML 2.4 For Beginners - 12: Collision Detection (AABB). 

the same: IM SUBBING

I got the same error, did you fix yours?

Same here, not sure what I'm doing wrong.

So I quess we will never get an answer what's wrong :(

Hey, I was just having this same problem and I fixed it by removing the & in the CheckCollision parameters. So instead of CheckCollision(Collider &other, float push), it is CheckCollision(Collider other, float push). (make sure to modifyt the header as well)

It needs you to store the players collider before passing it by reference, so Collider col = player.GetCollider(); , then pass col in. Since the getcollider returns a Collider, not a Collider* or & so as soon as that finishes it goes out of scope, meaning the pass by reference will be referencing bad memory. It's usually more efficient to pass by const reference for somewhat complicated data structures (aka anything thats not a standard int or float etc) but if within the function that is taking it, wants to modify that type - it cannot be const.

did you fix it? I got the same thing

@@aayushkarki108 nope, I've done the collider method in the class to resolve, but it isn't very correct

@@_simobr is it possible for you to share the resolved code?

@@aayushkarki108 meme its not properly solved

I got this error too, I don't know how he didn't get this. The problem is that in the getCollider function you are returning a temporary Collider object and you have a reference to Collider in CheckCollision function, you are trying to bind a non-const reference to a temporary object which is not allowed. What I did was create an empty default constructor for Collider class, create private default Collider objects in the platform class and player classes, then in the getCollider function I set these objects to Collider(body) and return that value. Lastly, I have the type of getCollider be Collider& (reference to collider object) instead of Collider. Now when you use pass in player.getCollider() in the CheckCollision method you are actually passing a reference to a non-temporary Collider object. There might be a shorter way to bypass this issue but this is what worked for me.

samee! ;(

+EricZeBaws The collider does not have to be a perfect square.

okay

Please tell me you sorted it out, and can share how, because I'm having the same problem, but it's either moving downwards or upwards. :D

I believe that issue is because you aren't multiplying by deltaTime.

This has something to do with the vs2017 and vs2019 compiler. With the vs2015 compiler you were able to directly use a returned copy as a constant reference, but you are not allowed to do this anymore with the vs2017 and vs2019 compilers. To fix this you simply have to store the collider in a local variable first and then pass that collider into the function, or change the function so it takes a collider instead of a constant reference to a collider.

@@HilzeVonck actually i am compiling this project using latest version of gcc compiler.

@@HilzeVonck I haven't quite figured out how to store the Collider inside of a variable, could you explain what you mean please?

me too, i don't now how fix ;(

see the comentary of Brian, fixed here

@@teamfortress2ful Who is Brian?

YOU HAVE TO TAKE & OUT OF collision & other, float push IN COLLISION.CPP AND COLLISON.H

@@camerontelford7667 Thank you so much!!!!

same

Hey did you fix this problem?

Hey.. For all who have the same problem, Here is the simply solution: ..... case sf::Event::Resize: ResizeView(window, view); break; } } Collider playerCollRect = player.GetCollider(); // (or) auto playerCollRect = player.GetCollider(); player.Update(deltaTime); platform1.GetCollider().checkCollision(playerCollRect, 0.5f); platform2.GetCollider().checkCollision(playerCollRect, 0.5f) ----------------------------------------------------- I hope i could help.. Nice Tutorials Hilze Vonck

@Mr.Lowpoly Hey thanks a lot man! Really needed this for my project. I also have a correction though: you spelt "CollRect" wrong on the platform1 and platform2 lines

@Chez Boyz Oh yes sorry .. I changed it, thanks

Maybe you should check if you are passing the body in the Collider class by a reference.

Hey. I got the same error. Did you manage to resolve it?

I've got this one too... If I find a solution I'll post it

Okay the solution I found was to put this line before we check collisions between (platform1 and player) and (platform2 and player in main.cpp: 'Collision (name of your Collider member) = player.getCollider(); After that, just replace player.getCollider with (name of your Collider member) in both checkCollision calls that follow

As far as I can tell, the compiler just didn't want us to use a member function for this variable. If anyone has a better explanation, I would love to hear it.

Not a solution, but I did this tutorial a while back on VS community 2015, and the code worked exactly as is, I am redoing it now to get back into SFML with VS community 2017, and I get this exact same error. So, perhaps it is something weird in the newest iteration of the compiler. And your solution did work for me.

there's a bunch of tuts on YT

Why isn't it a bool if it's always going to be either 1 or 0?

@@mort0303 it is not always going to be 1 or 0.. The case can happen that it is for example a heavy box and you want the push to be around 0.8 or so..

Edgar ah, ok. thank you

+EricZeBaws do you mean the border of the screen?

Yes

Here you go, this function will check if a collider touches the border of a view. bool TouchesViewBorder(Collider collider, sf::View view) { sf::Vector2f colliderHalfSize = collider.GetHalfSize(); sf::Vector2f colliderPosition = collider.GetPosition(); sf::Vector2f viewHalfSize = view.getSize() / 2.0f; sf::Vector2f viewPosition = view.getCenter(); float rdx = colliderPosition.x - viewPosition.x; float rdy = colliderPosition.y - viewPosition.y; float dx = abs(rdx) - (viewHalfSize.x - colliderHalfSize.x); float dy = abs(rdy) - (viewHalfSize.y - colliderHalfSize.y); if ((dx < colliderHalfSize.x * 2.0f && dx > 0.0f) || (dy < colliderHalfSize.y * 2.0f && dy > 0.0f)) { return true; } return false; } As you can see it looks almost exactly the same as the collision code for checking if two colliders are colliding. That is because a view also has a center position and a size. The only thing that really changed is the if statement at the end. This if statement consists out of two parts: (dx < colliderHalfSize.x * 2.0f && dx > 0.0f) and (dy < colliderHalfSize.y * 2.0f && dy > 0.0f). both of these parts basically do the same thing but one of them checks the collision on the x axis and the other one on the y axis. let's take one of these parts and see what it does. The first part (dx < colliderHalfSize.x * 2.0f) basically checks if the collider is within a certain range from the border (inwards), we need to multiply the halfSize by two because we need the full size for this calculation. The second part (dx > 0.0f) basically checks if the rectangle is within a certain range from the border (outwards). So the first part checks the collision for the left and top side of the collider and the second part checks the collision for the right and bottom part of the collider. The reason that they are separated by an or ( || ) is because we want this statement to be true whenever the collider is colliding with one of the sides of the view, and not just the corners.

Thanks so much!!

+Elijah Andrushenko Yeah, that is going to be the topic of the next video. :)

When we should expect it? :D

+SmykuPyka As soon as possible. I don't have any time to make an episode right now, but I'll probably have some time next week.

Please really help me i wanna make the game but i cant

Hey, the problem is that it is trying to get a reference to an object that isn't defined anywhere. The solution is to simply store the result of the getcollider function and use that variable as an input for the checkcollision function. This is an lvalue vs rvalue issue. vs2015 didn't see this as an issue, but since vs2017 the compiler started to treat this as an error. I hope this helps

@@HilzeVonck i love u Man. Thanks for fast response. You made mine Day better 😀

@@HilzeVonck anyway i am new and i work at sfml like 1 hours can u tell me how can i use code to do it and where should i put it please. Still thanks a lot dude

@@HilzeVonck i am 14years So i am bad xD

What this means is that the private variable body, will be initialized by the parameter body which is given by the constructor.

You can use the same code as is in the final check collision method. Just also pass in the position for the first aabb as a reference the size of the first aabb, the position of the second aabb as a reference and the size of the second aabb. It shouldn't be hard to convert this to a simple, c like function.

@@HilzeVonck converting it is the problem I just wanna *(see)* an example so that I know how it works. Everything being in objects makes it way to hard to pick apart. Also I'm asking in every RU-vid video about aabb resolution.

@ It could look something like this. (keep in mind that I just wrote the code and did not test it, so there might be some small syntax errors) The functionality of the function stays the same, the only thing that I changed is that we now are passing the positions and half sizes in directly, and we are also modifying these positions directly. Just make sure that the position that you pass in is the center of the AABB, and the size is half of the total size of the AABB. bool CheckCollision(sf::Vector2f& thisPosition, sf::Vector2f thisHalfSize, sf::Vector2f& otherPosition, sf::Vector2f otherHalfSize, float push) { float deltaX = otherPosition.x - thisPosition.x; float deltaY = otherPosition.y - thisPosition.y; float intersectX = abs(deltaX) - (otherHalfSize.x + thisHalfSize.x); float intersectY = abs(deltaY) - (otherHalfSize.y + thisHalfSize.y); if (intersectX < 0.0f && intersectY < 0.0f) { push = std::min(std::max(push, 0.0f), 1.0f); if (intersectX > intersectY) { if (deltaX > 0.0f) { thisPosition.x += intersectX * (1.0f - push); otherPosition.x -= intersectX * push; } else { thisPosition.x -= intersectX * (1.0f - push); otherPosition.x += intersectX * push; } } else { if (deltaY > 0.0f) { thisPosition.x += intersectY * (1.0f - push); otherPosition.x -= intersectY * push; } else { thisPosition.x -= intersectY * (1.0f - push); otherPosition.x += intersectY * push; } } } return false; }

@@Herovy070 wow to be honest this is way more than I could have asked for thank you I'll check it out when I get home. I appreciate it. I'm gonna go ahead and give you a like and a sub

Frixoe i

bruh he is detecting aabb to do the tile collsion

Nevermind, I can see that it works.

I have actually been working on rewriting all the code to upload to the site that I am building all day. All of the source code for this video should be up there. Here is the link: lucrifi.com/index.php/24-sfml-2-4-for-beginners-12-collision-detection-aabb?start=1. As a note though. The site is not yet finished at all, so if something is wrong or if something does not work, It'll be fixed as soon as possible. I think that the problem is either in the player's GetCollider() function or in the variables that you are passing into the CheckCollision() function. Make sure that the player's GetCollider() is NOT returning a reference to a collider. And make sure that the CheckCollision() DOES have references to the collider (both in the .h and the .cpp).

+Herovy070 whoops, I replied with my secondary YT account. Herovy070s reply is mine.

Thanks for the quick respons, I checked your link and checked your code with this page www.qualidator.com/WQM/de/Tools/TextDiff.aspx, I could not see any significant difference to my code, This is the play's GetCollider() Collider GetCollider() { return Collider(body);} and this is CheckCollision() in .h bool CheckCollision(Collider& other, float push); in .cpp bool Collider::CheckCollision(Collider & other, float push){

Hi,Thx for this great tutorial! I'm using code::block and got the same error even after copying all files from lucrifi.com/index.php/24-sfml-2-4-for-beginners-12-collision-detection-aabb?start=1. I've solved it by using bool CheckCollision(Collider , float).

Please help! I have the same issue, or if there is anyone else who has a fix for that matter.

I figured it out.

how @@christiancarter255

@@christiancarter255 what was wrong plz tell us

@@woff5 I wish I remembered 😔😭

@@christiancarter255 no worries someone had the same problem and had the awnser

Hey Ricardo, I got an error. Can you give me a hand?

yeah that's what I thought too

yeah same did you figure it out