# 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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### Swift - How do I detect the exact point at which two “SKPhysicsBody(edgeFromPoint:” type physics bodies intersect in sprite kit

I have two physics bodies attached to two separate sprite nodes using Sprit Kit. One is a vertical line and one is a horizontal line: //sprite with horizontal physics body ...
967 views

### How to detect collision of a wall with grid movement?

I have this little game, where my player is moving around a simple level, using a grid based movement script (See code below). My problem is that I have tried to implement a 2D raycast, which has to ...
219 views

### Collision between a sphere and a mesh(height-map)

I am trying to implement a method that detects the collision between a sphere and a mesh and reflects the vector of speed. I have a method, that detects a collision between a sphere and a triangle and ...
324 views

### Why does my character stop a little before landing on the ground?

I made a little game with side-scrolling and a box (the player) jumping across the level. The simple physics are almost done, but I have two problem with the way things behave: On landing, the box ...
151 views

### How to keep a shape inside a rectangle

So i'm making a game which is based on randomly generated rooms and i need a way to keep the player inside them and make the player glide when he collides with the room's bounds. I currently have a ...
134 views

### Ball oblique impact physic in Java?

I know Q3 + Q4 = 90 I searched internet and many physic topics, but not found how to calculate this values in Java? (I found V3 and V4 but not found Q3 and Q4) So how can i calculate V3, V4, ...
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I've been trying to implement collision for a platformer but I can't find a good way to get the collision of certain sides without it get glitchy. So i try to get the collision of the top rectangle ...
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### How can i fix my Ground detection code?

My ground detection works by checking if the player's x position is between the range of a sprite xpos+16 and xpos-16 if it is,then it uses a separate axis theorem on the y axis to see if the player ...
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### Moving a Polygon based on Camera position

I am in the process of implementing TMX Maps (made in Tiled) for my game. In Tiled, I can create polygons, which leaves a tag, containing the points. Loading in these points to a Polygon ...
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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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### Unity sprite with higher sorting layer not firing its OnMouseDown function

I have 2 objects, both have a Box collider 2D. The first object is on the Level1 Sorting Layer and has a Tile script attached to it. The second object is on the Level0 Sorting Layer and doesn't have ...
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### Bringing islands close together programmatically

I generate island/continent maps and I want to make a grand archipelago of sorts where all these islands are located. The problem is that I don't know a smart way to place the islands programmatically ...
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### Unity PHOTON/PUN Collision Detection

I am trying to create a virtual 3D chat room based on character interaction (just like in Sims2), so I have added a collider on the "user's in-game character". The problem is that when I enable the ...
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### Can't find out why aren't those collisions framerate independent

I'm making a 2D Platform game and I'm having trouble with my collision detection. It doesn't seems to be framerate independent even though I used deltatime there. The problem is that at 60fps, a ...
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### How do I find at least the closest penetrating point with SAT? [duplicate]

For more accurate simulations, I want to find the closest point of another polygon to one polygon's center when they collide. Is this possible with the SAT algorithm? Is it a good strategy at all for ...
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### Check for collision without any built-in collision functions

Is it possible to check for a collision between gameObjects without using the built-in functions OnCollisionEnter, OnCollisionStay, or OnCollisionExit? Preferably a solution without the use of ...
112 views

### How can I detect a perfect passageway for collision detection?

The problem is when I move diagonal it moves fractions of units and therefore my coordinates might be a fraction of a unit say (40,400) might be actually (40.12,400.40) but another problem is my pink ...
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### 2d Collision detection response equation doesn't work

I am currently doing some game engine programming as a hobby. I have been working on getting the collision detection working for a while now, and I'm at my wits end with it. I started with this ...
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### How and where to handle collisions? [Java] [duplicate]

Okay, so in my game I have a Level class, which hold an ArrayList of entities. In addition to this, I store the Player here (naturally enough). In my Entity class, I have a method which checks for ...
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### 2D Box Collision Trouble

Hello I am trying to handle some simple box collision (axis-aligned) in my top-down 2d game, but running into a problem. My game is running at a fixed time step, and checks for player-wall collision ...
134 views

### How should I improve my game world? [closed]

I'm in the process of teaching myself game development, and I'm trying to learn 3D, and started on a basic 3D game. The actual problem I've encountered is with level design, I'm using cubes all over ...
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### Handling collision with LWJGL rectangles

I'm testing collision with other rectangles so I can implement it into my current project. The problem is the rectangle starts at the right x and y, but I'm not sure where exactly they are. I'm pretty ...
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### In a collision detection loop, when do I apply the velocity?

I'm writing a really basic collision detection system (AABB vs AABB, AABB vs Circle, Circle vs Circle), and I've just got to the point of writing the actual loop which iterates the objects and checks ...
183 views

### (LibGDX/JAVA) How can I get a rectangle to rotate with this pendulum so I can start detecting collisions?

One of the objects in my game is a pendulum that swings in a semi-circle. This is done by having an update() method like this: public void update() { angleAcceleration = +1.81 / length * ...
78 views

### Unity material is missing after compilation

I have a piece of code that signals the player that a projectile has hit its target. Everything works fine during the playmode, however after I compile it, it acts as if there was a missing material. ...
215 views

### Game lags when my player collides with a specific object (solution known, unsure how to implement)

I'm developing a game in Android using LibGDX (although this is more of a JAVA problem than an engine problem). My aim is to have my player bounce off one spring onto another that will eventually take ...
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### Creating a custom collider shape in unity, and performance concerns

I want to create a custom chaped collider in unity to create point-defense triggers for objects. I have a spherical collider that triggers for attacking objects that enter it already. However I want ...
104 views

### Collision response callback

First at all, I'm not asking how to handle or detect collision. I already have that. My actual situation is, I have a system collision and I detect the collisions. Every collision detected is store ...
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### My “puck” model object falls right through the “table” model in jMonkeyEngine

So I am trying to learn jMonkey, I have understood everything so far, and I thought I understood how to make objects solid, so things can't go through each other. When I create my Collision shapes, I ...
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### How does one perform collision detection on objects made of many small triangles?

I understand that any shape can be created (or approximated) by smaller triangles. Any rectangle can be created by 2 smaller triangles. Any circle can be created by many thin "pizza slice" triangles. ...
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### Detect if two objects are going to crash

i am working on a car game where i am to create an AI, in the game there are other cars and a few objects moving around that i do not want to crash with, i have the speed, position and direction of ...
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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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### After collision of two objects change the sprite and move in its direction

I've searched a lot for this question but there was no answer that could solve the problem I'm having. I'm new to unity and a very naive developer.I'm making a game in unity using c# and it's like a ...
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### onCollisionEnter2D not behaving as expected

I have two game objects. They both have a Rigid Body 2D and a Box Collider 2D components. One of them also has script component. Below is the full script using UnityEngine; using System.Collections; ...
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### How can I get the “SelfActor” in OnBeginActorOverlap?

The signature it takes is void ( AActor* OtherActor ) However, The actor that is handling this event is not involved in the overlap. How can I access the actor that owns this delegate? Assuming I ...
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### Subdived objects in different shapes

Currently I'm working on an Android OpenGL 3D game and now I want to implement a collision detection. For this I want to use oriented bounding boxes but here is my problem. For a normal oriented ...
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### Fast(er(est)) fullscreen/scene collision detection technique (“selection buffer”)

My vertex format has a float4 Flags element used to pass miscellaneous data to shaders. Each mouse-collidable object that is rendered has a unique ObjectID that is written to an ObjectID-rendertarget ...
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### How can I split up a large model into an octree codewise?

For collision detection, I am attempting to split up a large model into an octree. If we take this black thing thing to be the ship (104,000 vertices): Then I would like to split up the faces I ...
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### Fast mesh collision 3D (C# XNA)

I'm trying to write a simple program where a 3D landscape can be walked about with a basic camera. However, I've found it very difficult to do even simple collisions with my terrain. I'm wondering if ...
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### Handling (spawning/removing) entities in SFML

I am unsure which method to use to handle my enemies in SFML. The idea that I am trying to recreate is to spawn enemies every so many seconds. Initially I wanted to do this using a vector such as ...
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### resolving per pixel collision issue

In space invader, I'm doing bullet to barrier intersection using rect to rect, then I'm testing the first bullet's impact pixel, if it's green I blast a circle, if it's black, it continues travelling. ...
60 views

### How to implement this collision detection function?

I would like to know how to implement this collision detection function, but I'm not even sure what it's called. The input shapes are 2D convex polygons, with an optional "rounding radius": imagine ...
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### missiles skip in collision detection

I'm trying to work on spaceinvader. I have problem that missiles or the bullets skip frames due to its fast speed. I tried to use the previous position of the bullet in the collision check, but still, ...
1k views

### Fast Ray Sphere collision code

I am looking at here and while it's well organized a lot of links are broken: http://www.realtimerendering.com/intersections.html I am trying to find fast code that will give me the hit point and the ...
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### Moving OBB vs. triangle intersection test

Requirements: to write a test function that, given a moving OBB (oriented bounding box) and a triangle, returns true whenever the OBB hits the triangle. The OBB is described by its half extents (h1, ...
461 views

### OnCollisionEnter2D incorrect contact point?

I am trying to shoot a bullet (rigidbody2d, boxcollider2d) to another enemy object (rigidbody2d, kinematic, circlecollider2d). I want the collision point between these two. When they collide, i want a ...
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### How do I make my main character move towards an object? LibGDX/Java

What I want to happen is for my player to bounce from spring to another. For example take the illustration below: Here's my code (what I've tried to do so far). This gets called in an ...
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### Unity Collision Difficulties (How do I make a ground in unity with lots of pieces that doesn't have poor collision?)

So I'm working on this game that I came up with the idea for while watching the Unity Roll-a-ball tutorials. So it's probably important to note that I'm extremely new to game design and I don't have a ...