The determination of whether or not two or more entities make contact with each other during gameplay.

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8
votes
4answers
4k views

Cocos2D collision detection against a random shape

I would like to brainstorm a few ways of handling how to detect a collision between a sprite and a user generated shape of some sort. For example. There are 3 objects on the screen. The user takes ...
7
votes
2answers
2k views

How do I find the point of impact with 2D per-pixel collision detection?

I'm creating a platformer and have implemented per-pixel collision detection. However, this has caused 2 obstacles that I've yet to figure out. The first obstacle, which this question is about, is ...
6
votes
1answer
184 views

Finding roots/zeros for collision detection?

For the most simple of 2D games, I have implemented a posteriori collision detection (overlapping rectangles) on the x/y Cartesian plane, but am now interested in understanding the basics of a priori ...
6
votes
1answer
776 views

AABB - AABB Collision, which face do I hit?

To allow my objects to slide when they collide, I need to : Know which face of the AABB they collide with. Calculate the normal to that face. Return the normal and calculate the impulse that to ...
6
votes
3answers
494 views

How to separate colliding objects without creating more collisions

Suppose I use a simple discrete collision detection system where I move all objects then check for collisions. I want any colliding objects to be separated (of course) and assigned appropriate ...
6
votes
4answers
2k views

2D Platformer Collision Handling

I am trying to create a 2D platformer (Mario-type) game and I am some having some issues with handling collisions properly. I am writing this game in C++, using SDL for input, image loading, font ...
2
votes
1answer
697 views

How can I test if my rotated rectangle intersects a corner?

I have a square, tile-based collision map. To check if one of my (square) entities is colliding, I get the vertices of the 4 corners, and test those 4 points against my collision map. If none of those ...
1
vote
2answers
760 views

How to calculate the direction a ball must bounce

I have a tile engine I have made. I can detect collision between the ball(the player) and the tiles. When a collision is detected all the colliding tiles are stored inside a list. My question now is, ...
8
votes
3answers
619 views

Ball vs 45-degree slope collision detection

I have a simple game in which the player moves a ball around. The ball bounces off of walls. Right now I have square walls(■) implemented: I use simple bounding-box collisions to check if the player ...
7
votes
3answers
2k views

Finding the contact point with SAT

The Separating Axis Theorem (SAT) makes it simple to determine the Minimum Translation Vector, i.e., the shortest vector that can separate two colliding objects. However, what I need is the vector ...
7
votes
1answer
2k views

Given a plane and a point, how can I determine which side of the plane the point is on?

Given the point Vector pos = new Vector(0.0, 0.20156815648078918, -78.30000305175781, 1.0); and the plane (triangle) Vector a = new Vector(-6.599999904632568, 0.0, -78.5, 1.0); Vector b = new ...
5
votes
1answer
495 views

box2d with lines

I have a very simple platform game builder and I've specified the ceilings, walls and floor as line segments. A line has a winding, or normal; you can determine the direction that a line should be ...
5
votes
1answer
1k views

Circle-Rectangle collision in a tile map game

I am making a 2D tile map based putt-putt game. I have collision detection working between the ball and the walls of the map, although when the ball collides at the meeting point between 2 tiles I ...
4
votes
3answers
1k views

Collision Detection in Java for a game

Im making a game in Java with a few other people but we are stuck on one part of it, making the collision detection. The game is an RPG and I know how to do the collision detection with the characters ...
4
votes
1answer
1k views

New Vector Calculation for Elastic Collision of Circle and Fixed Rectangle

I am writing a fairly simple breakout-style game for Android phones. I have successfully detected the collisions between the ball(s) and bricks. The problem that I am having is in calculating the new ...
3
votes
1answer
243 views

Collision Detection Efficiency

I've just written my first successful collision detection code, and it works great for a small scene of actors (player + 4-5 obstacles). However, I realize that since it checks every possible ...
1
vote
2answers
574 views

SAT, How Do I Find The Penetration Vector?

I've just successfully implemented Separating Axis Theorem (SAT) in my game but I was wondering how do I find the penetration vector? I heard it can be useful for collision response. e.g. The harder ...
1
vote
2answers
638 views

Which axis-aligned line does an AABB collide with first?

I am making the collision resolution system for my 2d top-down game, and I managed to find a solution where I query which surfaces of other AABBs the current entity can collide with in the next frame. ...
0
votes
2answers
2k views

Breakout collision using 2D Rectangles?

Here is my code: using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework; namespace BreakOut { class Field { public static ...
-5
votes
2answers
400 views

two balls stick together in a pool game? [closed]

when multiple collisions occur between balls..sometimes they stick together..mostly in cases of either of the balls having high velocity..can somebody explain pls
18
votes
6answers
2k views

How to optimize the distance function?

While developing a reasonably simple RTS-like game, I noticed my distance calculations were causing an impact in performance. At all times, there are distance checks to know if a unit is in range to ...
10
votes
1answer
3k views

How can I define a complex collision area on top of a tile map?

As many people recommended, I am using Tiled map editor to create a map for my game and it's great particularly because libgdx framework also provides with API for maps from Tiled. I understand I can ...
15
votes
2answers
1k views

Where should collision detection logic be placed?

I am developing a small 2D game engine. The characters have a paint method which currently does the following: Calculate the new position of the character as per its speed, etc. Update the collision ...
10
votes
2answers
1k views

Continuous Physics Engine's Collision Detection Techniques

I'm working on a purely continuous physics engine, and I need to choose algorithms for broad and narrow phase collision detection. "Purely continuous" means I never do intersection tests, but instead ...
14
votes
5answers
5k views

Collision Resolution

I know quite well how to check for collisions, but I don't know how to handle the collision in a good way. Simplified, if two objects collide I use some calculations to change the velocity direction. ...
13
votes
4answers
1k views

Optimizing collision engine bottleneck

If this is your first time on this question, I suggest reading the pre-update part below first, then this part. Here's a synthesis of the problem, though: Basically, I have a collision detection ...
6
votes
1answer
658 views

Creating custom collision map for 2D

I have a 2D level that I have built in my map editor, and I was wondering the best way to create a collision map for it. I have a collision map layer in my map editor, which saves each node (for ...
9
votes
2answers
482 views

Boat passing under a bridge in a 2D tile based RTS

I'm writing a 2D tile based RTS. And I want to add a 'pseudo 3D' feature to it - bridges over the rivers. I havent't start any coding yet, just trying to think how it fits the collision detection ...
6
votes
3answers
6k views

2D Side Scrolling game and “walk over ground” collision detection

The question is not hard, I'm writing a game engine for 2D side scrolling games, however I'm thinking to my 2D side scrolling game and I always come up with the problem of "how should I do collision ...
4
votes
2answers
1k views

Correct order of operations in a platformer game loop

I've run into an issue with my Mega Man engine, and the structure of my game loop is making it very difficult to fix. With Rush Jet, or any falling platform, Mega Man needs to stay attached to the ...
2
votes
3answers
855 views

Coarse Collision Detection in highly dynamic environment

I'm currently working a 3D space game with A LOT of dynamic objects that are all moving (there is pretty much no static environment). I have the collision detection and resolution working just fine, ...
0
votes
5answers
865 views

Collision detection logic

Edit 2 In the following picture sprite1 (the red square) is hitting the platform from the left, so: sprite1_rightEdge>platformSprite leftEdge would be true, so I can simply reposition ...
7
votes
3answers
2k views

Collision detection with curves

I'm working on a 2D game in which I would like to do collision detection between a moving circle and some kind of static curves (maybe Bezier curves). Currently my game features only straight lines ...
2
votes
2answers
958 views

Projectiles in tile mapped turn-based tactics game?

I am planning to make a Laser Squad clone and I think I have most of the aspects covered. But the major headache is the projectiles shot/thrown. The easy way would be to figure out the probability of ...
8
votes
1answer
630 views

Are there well-known algorithms for fitting a polygon to an arbitrary shape?

I'm using the Chipmunk physics engine to make the levels for a 2D C game. I'd like to be able to fit a polygon to an arbitrary shape to serve as the collision mask. Given a black and white collision ...
7
votes
5answers
764 views

How do I calculate distance from a point to a rectangle?

I have a 2D rectangle with x, y position, height and width, and a randomly positioned point nearby. Is there a way to check if this point might collide with the rectangle if it is closer than a ...
5
votes
2answers
2k views

Collision Detection, player correction

I am having some problems with collision detection, I have 2 types of objects excluding the player. Tiles and what I call MapObjects. The tiles are all 16x16, where the MapObjects can be any size, but ...
4
votes
5answers
541 views

Collision detection performance problem

Using python and pygame I've built a collision detection system according to the instructions in this YouTube tutorial. This is updated 40 times per second and controls movement and collision ...
4
votes
2answers
1k views

Sliding collision response

I have been reading plenty of tutorials about sliding collision responses yet I am not able to implement it properly in my project. What I want to do is make a puck slide along the rounded corner ...
4
votes
1answer
1k views

How can I convert a 2D bitmap (Used for terrain) to a 2D polygon mesh for collision?

So I'm making an artillery type game, sort of similar to Worms with all the usual stuff like destructible terrain etc... and while I could use per-pixel collision that doesn't give me collision ...
3
votes
1answer
260 views

Moving the jBullet collision body to with the player object

I am trying to update the location of the rigid body for a player class, as my player moves around I would like the collision body to also move with the player object (currently represented as a ...
3
votes
3answers
244 views

Physics System ignores collision in some rare cases

I've been developing a simple physics engine for my game. since the game physics is very simple I've decided to increase accuracy a little bit. Instead of formal integration methods like fourier or ...
3
votes
2answers
1k views

3D Ball Physics Theory: collision response on ground and against walls?

I'm really struggling to get a strong grasp on how I should be handling collision response in a game engine I'm building around a 3D ball physics concept. Think Monkey Ball as an example of the type ...
2
votes
1answer
1k views

Would someone please explain Octree Collisions to me?

I've been reading everything I can find on the subject and I feel like the pieces are just about to fall into place, but I just can't quite get it. I'm making a space game, where collisions will ...
2
votes
1answer
2k views

How do you implement 2D collision detection?

I would like to know the best or most efficient way to test for 2D collision. I am currently using AABBs. But the problem with this, is that your objects will be hitting things when they shouldn't. ...
10
votes
2answers
499 views

How do I make good guy attacks only hit bad guys and vice versa?

My game has many different type of good guys and many different type of bad guys. They will all be firing projectiles at each other but I don't want any accidental collateral damage to occur for ...
9
votes
4answers
1k views

Collision rectangle response

I'm having difficulties getting a moveable rectangle to collide with more than one rectangle. I'm using SFML and it has a handy function called intersects which takes 2 rectangles and returns the ...
7
votes
5answers
1k views

How to determine which cells in a grid intersect with a given triangle?

I'm currently writing a 2D AI simulation, but I'm not completely certain how to check whether the position of an agent is within the field of view of another. Currently, my world partitioning is ...
7
votes
3answers
679 views

Your recommendation for path construction from a single background image?

So I currently have my background as a single PNG and some obstacles (like blocks as part of that PNG). In order to create a path, I currently store pixels above a unique green color (my hill) and use ...
6
votes
2answers
2k views

How do I handle collision detection so fast objects are not allowed to pass through walls?

I'm creating a 2d sidescrolling shooter, and I'm having a little trouble with collision detection for the bullets. Everything including the bullets are objects with their own polygons / update ...