Tagged Questions

A process of adjusting game objects position after collision.

3k views

Hexagon collision detection for fast moving objects?

A object has a position and a speed vector. Usually only the position is used to check if two objects collide, this is problematic for very fast moving objects as it can happen that the object moves ...
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How to deal with corner collisions in 2D?

I'm writing a top down 2d XNA game. Since its my first I'm trying to write the physics and collision stuff myself to learn it. Whenever my player sprite character attempts to move into a position ...
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How do I calculate rotation caused by bounce friction?

Following on from my previous question: I have the ball quite realistically bouncing from surfaces it hits. Now I'd like to make it spin from the friction of the hit. Showing this is simple enough: I ...
4k views

Resolving a collision with forces

In my 2D physics engine, I can detect AABB vs AABB collisions, and resolve them by finding the shortest penetration vector and adding it to the AABB's position. Doing this "pushes" the first AABB ...
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Storing coordinates of every object in server side in MMOs

In an MMORPG: Is it typical or feasible to store the coordinates of every tree, bush rock.. etc in the server side for collision detection? If so, what would be a feasible way to store such a huge ...
7k views

Collision resolution in case of collision with multiple objects

I have static objects and movable objects. The collisions are detected using the separating-axis-theorem. For example, in this situation I have two static objects (in red): and a movable object ...
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Make the player run onto stairs smoothly

I have a 2D Platform game, where the player Always runs to the right, but the terrain isn't Always horizontal. Example: I implemented a bounding-box collision system that just checks for ...
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Microsoft XNA Platformer Example, is the Collsion Detection implemented accurately?

The example provided by Microsoft seems as if the collision detection (from what I can see) will have a small error. When the user collides with an Unpassable tile, the depth of the intersection is ...
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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 ...
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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 ...
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Strategies for dealing with crowds at choke-points

I've recently switched my game engine over from steering behaviours to impulse based movement with proper time based collision resolution. This has solved so many problems (no more tunnelling, yay) ...
1k views

Reusable top-down collision class

I've recently picked up monogame and am working on a simple top down game to get me started and learn the basics. I've got the movement and the rotation to follow the mouse sorted out but I'm stuck ...
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How to resolve penetration of two colliding bodies

I've implemented simple 3D game physics engine. I already have decent collision detection in place, now I'm trying to figure out the collision response part. I'm using impulse based method to ...
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Need efficient way to keep enemy from getting hit multiple times by same source

My game's a simple 2D one, but this probably applies to many types of scenarios. Suppose my player has a sword, or a gun that shoots a projectile that can pass through and hit multiple enemies. ...
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Collision Detection Game Design and Architecture

I've reading some articles about collision detection. My question here is about ideas on the design for it. Baically I have a C++ game that has a main loop with entities with an update method. Based ...
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How to implement friction in a physics engine based on “Advanced Character Physics”

I have implemented a physics engine based on the concepts in the classic text Advanced Character Physics by Thomas Jakobsen. Friction is only discussed very briefly in the article and Jakobsen himself ...
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Collisions between players in multiplayer racing game

I'm creating a simple racing game (spaceships, no gravity) using p2.js, phaser and node.js. What I have done: Client receives world state from server: extrapolate other players based on latest ...
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How do I restrict the movement of a point to within a radius of another?

I have a situation where a sprite's center point needs to be constrained within a certain boundary in 2D space. The boundary is circular, so the sprite is constrained within a radius. This radius is ...
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Calculating impulse propagation through a rigid body after a collision

I'm working on a game. I need to work out what the impulse is at different points on a body as a result of a collision. For example, in the following diagram, if there is a collision that results in ...
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Implementing Separating Axis Theorem (SAT) and Minimum Translation Vector (MTV)

I was following codezealot's tutorial on SAT and MTV and trying to implement it myself but I've come a cropper when it comes to getting the correct MTV. Here is my example: (Cue pretty pictures...) ...
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Collision Detection problems for vertically moving platforms

Background My game is a static screen (ie, no scrolling) 2d platformer and my CD routine is split into 2 - after vertical movements, (ie, gravity etc) I check for collisions, and if they are detected,...
379 views

Circle Collision Resolution and Angular Momentum

I have a 2D engine working pretty well that involves rectangles and circles. I just reworked parts of the collision detection/response system for better handling of angular speed/momentum. The ...
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Need some advice regarding collision detection with the sprite changing its width and height

So I'm messing around with collision detection in my tile-based game and everything works fine and dandy using this method. However, now I am trying to implement sprite sheets so my character can have ...
2k views

How do I resolve a collision of a rectangle with two rectangular tiles at once?

I am having some problems with collision detection between a player and the environment in a tile-based game. I have a player objects, Tiles and what I call MapObjects. The tiles are all 16×16. The ...
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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 ...
264 views

Creating an unbiased deterministic collision resolution order

I'm working on a game with a replay system, so I need the game logic to be deterministic. A part of this is collision detection and I'm having a bit of a conceptual problem here. (I'm programming in ...
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Move penetrating OBB out of another OBB to resolve collision

I'm working on collision resolution for my game. I just need a good way to get an object out of another object if it gets stuck. In this case a car. Here is a typical scenario. The red car is in ...
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Handling collisions with ground

How do you usually solve collisions between entities and the ground? Sending collision events hardly seems appropriate since almost everything touches the ground at almost all points in time. Calling ...
1k views

When two moving objects collide, which one sends the message, and which one recieves it?

I am writing a platform game using an entity-component system. Entity-World collisions are robust and work very well, and I'm now working on collisions between entities. Just to be clear, in my code ...
147 views

Finding new position after collision with multiple colliders

What is the most accurate way to find the correct position to where a moving character should be re-positioned as a collision-resolution, after it has collided with multiple colliders? The figure ...
516 views

Help me please to choose proper path-finding algorithm

I am new to game development and just want to ask for advice. I need to know which path-finding algoritm will be suitable for my scenario: Units - any shape. But in most cases rectangles of ...
831 views

How do I resolve a sphere-triangle collision in a given direction?

I am trying my hand at game physics. I understand that the basic way to pull back a sphere when it collided is to negate the penetration distance: // If collided... // `distance`: distance form ...
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How do I make a collision between AABBs slide?

I have a room with objects inside. Each object has it's own AABB. I know how to check for collisions between the objects with an AABB-AABB intersection. How do I calculate an appropriate collision ...
678 views

Allowing a player to walk up and down slopes without resistance

I am trying to implement a platformer where both the player and the level are made up of arbitary polygons. One requirement is that the player can stand still on slopes, and walk up and down them ...
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Collision with tile corners/seams in 2D platformer

There seems to be a lot of somewhat related questions answered already, but none I read answered my exact problem. I have a 2D platformer whose world is made entirely out of tiles that are in a ...
716 views

Calculating impulse with multiple collision points

In my amateur 2D rigid body physics engine for a game I react on collisions between two bodies with an impulse j (formula 11) as explained here. To calculate this impulse I need one contact point P ...
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2D AABBs and resolving multiple collisions

Okay, so this is a problem I've been trying to figure out for quite some time. Mine is a 2D platformer game with a world made up of (usually) immobile tiles and mobile sprites, both of which use AABBs ...
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How to handle the top of a slope in a 2D tile-based platformer?

I'm working on a 2D tile-based platformer that supports 45-degree slope tiles. There are several questions on the topic, but none seem to cover this precise problem that I have. This excellent ...
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XNA Collision is quircky/wobbly, how to improve?

I am sorry if this was already answered but I couldn't find the answer. So I am doing a tile based platformer and when I was making collision I had quiet a struggle I looked here and googled for ...
195 views

Why is my collision resolution failing on the corners?

I'm tearing my hair out trying to work out how to handle my collision resolution at the corners of the rectangles that I'm colliding with. The code that I'm working with is: class Player(object): ...
463 views

2D Collision response - rotating, moving polygon hitting a wall

I'm trying to bounce a polygon that has both velocity and angular velocity off a (immovable) wall when one of the vertices collides with it. I can detect the collision, and I've worked out how to ...
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XNA 4.0 / C# Collision Response

Okay, this is really starting to annoy me. First of all, detecting collisions is nice and easy. I have a list of tiles, and a player. The player and each tile have their own rectangles. (The tiles ...
519 views

How to handle collision resolution in a top-down car game?

I have a top-down car game which takes place in an arena. The game is very very light on physics, so I'm not actually using a physics engine. The cars' movement is mostly managed by a struct I called ...
142 views

Collision Response: game character vs. density function

Introduction I am working on my own "novelty" game-engine project, where the world is represented by a continuous density function. It has only one interface, a function that returns the density at a ...
315 views

Lerping character moving up and down slope tiles

So, when interpolating position against a standard 'horizontal' platform, everything works great. What happens is something like this..... (Question continues after graphic) Now, the question I ...
844 views

Meaning of offset in pygame Mask.overlap methods

I have a situation in which two rectangles collide, and I have to detect how much did they collide so so I can redraw the objects in a way that they are only touching each others edges. It's a ...
742 views

Character jittering with this tile based collision code

I have been trying to get my collision code working for hours now but with every resource I have tried my character still jitters. First I tried using the platformer sample but my character still ...
624 views

How do I avoid pathfinding characters getting stuck in corners?

I used A* pathfinding to return a list of Tiles to get from an enemy to the player. After that, I wasn't sure how to actually move the enemy. What I ended up doing was get the first Tile in the path. ...