# Tagged Questions

Collision detection is the determination of whether or not two or more entities make contact with each other during gameplay.

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### multiple contacts for SAT collision detection

I have implemented SAT algorithm for obb-obb intersection and I am able to generate a contact for this collision type. My problem is that SAT only generate ONE contact and in many situation I need ...
116 views

### Separating Axis Theorem - Calculate Normals from Points in 3D

So while researching for a method to detect collisions in a 3D space between (arbitrary rotated) boxes, I stumbled upon this excellent question with great resources for my further research and great ...
146 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 ...
160 views

### How to make your own 2D AABB collision system in unity?

I can't use the built in unity 2d physics engine for my game, so I tried to make my own using the unity bounds.Intersects, that is working perfectly but my problem is that I don't know how to make the ...
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### Libgdx: Check collisions in Stage among actors

My goal is to check collisions among the actors that are in the Stage. My question is: is it necessary to maintain a list for each type of actor I have? Doing that I get 3 problems, 2 bad design ...
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### Jumping onto higher ground Collider issues

What's the general solution to the following character animation problem (I'm using Unity)? You have a character with a capsule collider and a jump animation that allows you to jump onto higher ...
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### Two dimensional elastic collision of balls

I am trying to create a simple elastic collision simulation in java. (I am using some helper libs like StdRandom) Here is my Ball class : class Ball { double cx, cy; Vector velocity; ...
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### Collision between complex polyominoes travelling at different velocities

My first post here if there's anything wrong please do highlight it :) First and foremost the problem I'm facing is practically identical to this earlier post here : Falling Blocks and complex shapes ...
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### Character Movement and Collision with Ragdoll Rigidbodies/Colliders?

I have a player character that I'm moving with a character controller script and it is moved by applying velocity to a Ridigbody. This works when I have a rigidbody component on the player but my ...
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### Wall checking not working correctly

Basically I am working on side scrolling 2d game. For that I want to check whether player is collided with wall. I have written some code for it but can't able to decide where I have done stupid ...
347 views

### OnTriggerEnter / OnTriggerStay triggers multiple times and is not been call a second time

I am working on a feature that when the Player pass thru a door, a message will popup on the screen. I'm having few problems: Debug.Log gives me from 2 to 6 logs when I pass thru the collider plane ...
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### My collision detection is not working when I rotate my mesh in three.js

I am trying to move a ball mesh through a maze. The maze belongs to a parent object3d. My issue is that when I move the ball I can't detect collision right well because in the rotation, the axis ...
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### My player sprite get stuck to walls while moving along

Hello, My player sprite is moving along the wall (not even diagonal, just straight down) and get randomly blocked in the corner of some walls. By blocked, I mean that the Y movement is stopped. If I ...
144 views

### Efficient datastructure to store a galaxy map

I'm working on a project for an intro level Ai class, and the project I've closen is to create a simulated universe in which Ai actors play against each other economically and militarily. I have the ...
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### Mouse Interaction in 3D space (ray)

I use this code public static Ray CalculateRay(Vector2 mouseLocation, Matrix view, Matrix projection, Viewport viewport) { Vector3 nearPoint = viewport.Unproject(new Vector3(...
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### Finding collision point of moving projectile/bullet with a cube

I am programming a game in the spirit of Wolfenstein 3D (2D grid map, 1 cell = 1 cube) and I wanted to implement shootings. I didn't want the shootings to happen in one frame so, I wanted to see the ...
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### 2D Collision at corners using C# - without xna or unity

I'm trying to make collision for a 2D game, the player (car) has to collide with the walls of the track when it hits them. I looked into pixel color detection, and X,Y -based collision (But since its ...
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### GJK algorithm in case of circle and polygon?

I wonder if it's possible to modify GJK so I can use it to detect collision between circle and n points polygon. I implemented for polygon and polygon before, and I tried modifying the support ...
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### Matching collider to character mesh size in different postures

What's the optimal method in Unity to match the size of a Capsule Collider to the actual size of the game object it is part of? To understand what I'm trying to do let me give an example: I have a ...
153 views

### Detect walking on floor - works partially

I have a set of Gameobject blocks that form a floor with Box Collider and a GameObject with a Box Collider in it. My first hunch detecting hitting the floor was: void OnCollisionEnter2D(Collision2D ...
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### How do I efficiently check if a point is inside a rotated rectangle?

Part for the sake of optimization, part for learning purposes, I will dare to ask: How can I most efficiently check whether a 2D point P is inside a 2D rotated rectangle XYZW, using C# or C++? ...
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### Collision detection with moving objects

I searched a lot about this problem. I found many answers here in Stack Exchange but none of them really answers when positions for objects get updated. For a game with fixed size map and that has ...
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### XNA Collision In An Entity Part System

I've hit a loss in creating a "game engine" in XNA, I'm extremely confused over how to approach collision in an Entity-Part System ( following this as a reference ). I can make all the entities with a ...
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### 2D Collision Box Clipping

There is this strange issue with the collision in a game I am making. When the player is slightly lower than a block it is colliding with from the side, the player ends up clipping to the top of the ...
156 views

### Detecting collision with walls (is this a good solution?)

I'm trying to make the collision smooth (it must open the animation, but not move the character). I've implemented 'fake positions': int step = 20; fake_left_x = x-step; fake_right_x = x+step; ...
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### What is the most efficient way to determine collision path

I am trying to create a game in which I need to know if two objects will collide in the future, and when. I have both object's position, radius (they are circles) and velocity. A specific example of ...
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### Platformer collision problems

I am working on a platformer 2D, and i am currently focusing on collision. I have the actual rectangle(class: Rect) and i can detect if the player-model is intersepting it. However, when it comes from ...
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### Most efficient way to get the world position of the 8 vertexes of a Box Collider (C#)

What I am looking for is the most efficient way to get the world position of the 8 vertexes of the Box Collider of a freely rotated Gameobject. I cannot use collider.bounds since object is rotated, ...
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### Detecting the two Vector3 that determine the bottom-edge of the side of a box-collider that had collision (with C#)

So, I understand that plenty of questions have been posted on how to detect which side of a Box Collider had collision. However, what I am trying to achieve is a little different. I want to find out, ...
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### Combining Many Small Colliders into Larger Ones

I am creating a game using a tile-map made of many thousands of grid squares. At the moment, each square has a square collider on it for checking collisions. However, with many thousands of tiny ...
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### How can I exploit multithreading in collision resolution?

I'm trying to speed up my collision resolution by using multiple threads. I'v read through Box2D's source code and while it was challenging and educating, it didn't really point me to how I could use ...
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### Ray & Segment Intersection

I'm writing some code to check intersection between all of a rectangles segments and a ray. It will sometimes use the Left and Right side of the rectangle as the closest face hit (face DA & BC) ...
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### JBox2D Collision Detection

how can i detect a collision between two fillOval with the physics engin?? i read the manual but i can't understand where i may write my code. i want to simulate the fall of 2 balls and catch the ...
741 views

### Colliding without physics in Unity: is it possible to put OnTriggerEnter in the moving character?

My main question is: is it possible to put OnTriggerEnter in a script that goes attached to the moving character instead of to trigger area/object? Let me explain my exact need. I want to detect the ...
217 views

### How do I check for collision between an ellipse and a rectangle?

I am working on LibGdx framework for developing a 2D isometric tower defense game.All my sprites are drawn in 2D isometric view. I have used an array list to store 8 points at boundary in the ...
259 views

### How do I create a draggable object which snaps to obstacles in the way?

I bring yet-another-drag-with-mouse question (I am using Unity with C#), but with a less common particular detail: the existence of obstacles in the middle of the way trough which dragging occurs (3D ...
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### My Sprite is disappearing when it collides with my floor (libGDX)

I am just starting to build the game "engine" and I am using a sprite drawn in the same position as a rectangle and the two always move together. I have another rectangle which is the floor when the ...
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### Spawning Object 1 Within Object 2's Collision Box [Gamemaker]

I was wondering if any of you could help me with a specific Gamemaker question. Am using Gamemaker Studio. I have an object (oSpecialSolid) which rotates and moves across my level. At random ...
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### Player Flying after colliding - Unity

I have a Player with a capsule collider on him and i have various objects in the scene. Most of the objects have either mesh collider or box collider enabled. When i move my player and the player ...
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### Circle inside ellipse collision/intersection (preventing circle from leaving the ellipse)

I am working on a 2D RPG with a turned based battle system. Characters move inside the confines of an ellipse movement area and when they leave the boundaries will be pushed back inside. (i.e they ...
370 views

### Soft Body Collision with Box2d (libGDX)

I've made a few classes to create soft body objects in libGDX using Box2D (specifically a circle and rectangle similar to these links). The objects are constructed of a number of circle shaped Box2D ...
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### Bounding Volumes for Empty Space

I'm creating an Android game that relies heavily on collision detection for a couple of players (at least up to 4). I researched hierarchical structures that could speed up the process. Because I have ...
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### Fastest 3D bounding box algorithm

I am at the point in my game where I need to add a collision system. I tried jBullet, and while it did work, it wasn't what I was looking for. I just want a simple way to test if two oriented bounding ...
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### Move collider along with model with Mecanim jump animation

I've been creating an infinite runner game in Unity3D for a while and I got stuck in this point that whenever my character jumps using Mecanim system his model (mesh) goes to air but his attached ...
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### Continuous Collision Detection

So I'm playing around with the separating axis theorem and collision. Obviously the problem of what face it collided with arose. I need the unit normal which is tangent to that face it collided with ...
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### simple solution for 3d collision detection and response

I'm having great difficulty trying to implement collision detection and response in a 3d game What are some simple solutions someone can use to implement smooth collision and response similar to ...
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### Unity - Raycast not hitting to BoxCollider2D objects

I'm working on 2D and I have a Quad as background. And some wall sprites over this quad : I'm instantiating wall prefab sprites over quad when user click to somewhere. But I don't want to ...
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### Field of vision - Objective-c

Here's where I'm at. Here's where I want to be Here's how it's drawn SKShapeNode *fov = [SKShapeNode node]; UIBezierPath *fovPath = [[UIBezierPath alloc] init]; [fovPath moveToPoint:CGPointMake(...