# 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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### 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 ...
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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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### 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 ...
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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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### 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 ...
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### How do I compute the angle between a pixel on an irregular curve and a circle colliding with it?

I'm building a custom physics engine to accompany a level-editor. This image shows how the level-editor outputs levels: Now, some explanation is in order. The curve is defined by the red points. ...
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### beginContact triggered more than once on some objects

Short version: It looks like beginContact is detecting continuous collisions. I'd like to avoid that. Long version : I use Box2Dweb to write a 2D platformer. It's my first game using this lib, and, ...
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### Why does my RigidBody collision fail depending on which entity is moving?

I am working on a UDK project and have a collision problem. I have a Crate which is a kActor with RigidBody physics and my player who is a Pawn. When my player moves and collides with the crate, the ...
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### What is the most effective way to create a set of collision points for an aribitrary mesh?

In my project I am working on automatically deforming an arbitrary mesh with respect to another arbitrary mesh, within the context of user generated content, similar to this deformer being developed ...
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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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### 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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### 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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### 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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### 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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### 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 ...
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### 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 ...
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### How is curved 2d ground is implemented in real games?

I'm developing a 2d platformer (inspired by N game) and I already successfully implemented circle-convex, convex-convex and circle-circle collision. But now I want to be able to make platform that ...
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### XNA4\ Monogame 3d Collision detection Help please

i have been trying to get 3d collision working for a while and i think(hope) you people can help me so for my project i have created a 'sprite3d' kinda class which is called ModelEntity and there ...
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### Efficient Collision detection for polygons (fleet) in an RTS

I'm trying to make an RTS for android using libgdx. I would like to have collision detection to be able to detect ships inside the range of weapons and collision between my bullets and the ships. So ...
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### Implementing Separating Axis Theorem to Detect and Handle Sliding Collisions

I am having a bit of difficulty detecting collisions properly with separating axis theorem. My code seems to be giving a lot of false alarms. Also, I've looked into implementing sliding collisions ...
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### Collision detection with PyGame

I have been making a 2d platformer using Python with PyGame. It has all be going good, but I have stumbled accross many problems with collision detection. Here they are: You can't go through objects ...
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### How do I find the intersection point from the Expanding Polytope Algorithm?

I've successfully implemented a 2D version of the GJK and EPA algorithms which gives me correct collision information, including collision normal and penetration depth. What it doesn't give me ...
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### Using Box2D in LibGDX, is there a reason a fixture set to be a sensor would only -sometimes- detect a collision?

I am working on a 2D game in LibGDX. Currently, I am testing interactions between a player's weapon and enemies - in particular, a sword and an enemy monster. The player has a hurtbox and the sword ...
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### Collision Detection Between 3 or More Objects

Say I have a 2D grid of particles, and I wanted to find out if any of them were colliding. In my head I have come up with a system where you check every possible location for each particle in that ...
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### Is there a way to rotate an Ellipse in libGDX for collision detection purposes?

I'm trying to avoid having multiple overlapping Circles for a UFO-shaped sprite. Two Ellipse objects will perfectly cover the shape of my UFO, but I want to tilt/rotate the UFO when flying left and ...
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### Manual response when 2 shapes made of rectangular volumes collide

I have 2 compound objects made of rectangular blocks. One of them (the one that is moving) has a script that listens to OnTrigger callbacks. What I need is to position the moving compound object on ...
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### 2D Distance Field as collision handler method

Pixeljunk Shooter has really cool fluid simulation. I found the dev's video explaining what they did. Here I understand that it is particle based simulation Smoothed Particle Hydrodynamic I can ...
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### How do I detect collisions between a particle-based net and a ball?

I've implemented a net using Verlet integration and many points connected with constrains; like this demo, but in 3D. I want to implement collision detection between this net and a ball (like in a ...
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### Collision detection implementation suggestions

I'm working on a simple 2D game involving a rotating octagonal ring where a sphere sprite moves up/down avoiding objects as the ring rotates faster and faster. I'm having a difficult time with the ...
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### LibGdx Triangle Collision

I'm back with another question. I'm trying to get a collision between an actor and a sprite. With the actor, which only moves upwards and downwards, I've got no problem since it's shape is a ...
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### How to Calculate K-Dops Faster

Ok so I have my general understanding of K-Dops for collision detection. I understand how to calculate them. I also understand the super slow way of recalculating them. Example: I have a simple ...
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### Bullet Physics ConvexDecomposition?

I've looked at Bullet Physics ConvexComposition Demo and would like to implement that in my game but the code is so undescriptive and it's hard to understand what is going on. Would any of you people ...
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### Collision detection 3d rectangles using SAT

This question builds on a previous post asked by griffinHeart nov 2012. See link below. How many and which axes to use for 3D OBB collision with SAT Refering to the explanation/answer by Ken. What ...
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### Setting up 3d Collision for Primitive shapes

Im having some trouble understanding how to set up collision detection between my first person camera and my primitive shapes which are made using the vertex buffer. Do i give my camera a boundingBox ...
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### Storing rigid body collision shapes in local or world coordinates

I'm writing the beginnings of a lightweight 2d rigid body engine (in javascript, as a hobby project), and i'm debating whether to store collision shapes in local or in (updated as needed) world ...
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### Collision Avoidance/Steering around moving obstacles

I've done a decent amount of research and I've read up on pathfinding algorithms and such, but I can't seem to find anything to do with the mentioned behaviors when moving around obstacles that also ...
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### Speeding up point-in-polygon for Python

In researching collision detection methods for non-Rect-like objects I came across point-in-polygon -- specifically, the even-odd rule. The one presently on Wikipedia claims it is written in Python, ...
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### How to identify whether the boundingvolume intersects with walls or floor when it doesnt return normals?

My game in jMonkey is the kind that use will have to place objects in a scene (which consist of walls and slabs and floor). All my models are centered at origin. When the user click a point I use ray ...
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### Aiming with a crosshair with a lot of polygons/triangles

I'm working on a 3d kindof game where I'll eventually be able to modify the shapes present in the environment by pulling their faces with a crosshair. The thing is that I don't know how to achieve ...
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### scale rotating boundingbox

I want to use basic rectangular collision detection. I have a rotating sprite and a method that calculates the bounding box every time in the Update() method. I simply check for intersection between ...
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### How can I implement collision for a “pseudo-3D” game?

I'm looking for high level implementation details, not specifics. I've worked with bounding boxes before in some 2D games, but I'm currently tackling a "2D + depth" (2.5D?) style game along the lines ...
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### Sketchy results from ray-plane intersection code

I've set up a demo with simple first-person controls using C++ and OpenGL, and it seems to work reasonably well. My goal is this: when the player looks at a plane and clicks the left mouse button, ...
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### iOS cocos2d - sprite gets stuck in collision detection

I'm developing a top down game in cocos2d and I have collision code that checks collisions between enemies and the player so that they don't go through each other. The code seems to work but the ...
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### Why do restitution values less than one still cause infinite bouncing in Box2D?

I'm currently trying to implement basketball bouncing into my game using Box2d (jBox2d technically), but I'm a bit confused about restitution. While trying to create the ball in the testbed first, ...
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### Detect Sprites, they are in Shape or Not which random draw in Cocos2d

I have searched a lot on web and found some of help ful links as exact my question. Link 1 Link 2 But still i am not success to achieve this, i have done some of code lines, as like draw line by ...
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### Getting collisions with equal values in Sweep and Prune

When sorting an (incremental and persistent) SAP, you generally move extremas left until you run into a smaller/equal extrema, gathering collisions along the way. However, that results in the ...
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### What is the best way to implement collision detection using Bullet physics engine and a track generated from a curve?

I am developing a small racing gam, the track is generated from a curve. As said above, the track is generated, but not infinite. The track of one level could fit with no problem in memory and will ...
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### Updating physics for animated models

For a new game we have do set up a scene with a minimum of 30 bone animated models.(shooter) The problem is that the update process for the animated models takes too long. Thats what I do: Each ...