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Questions tagged [separating-axis-theorem]

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OBB vs Frustrum collision detection

Some definitions: An oriented bounding box (OBB) is a rectangular block which can be represented in many ways, as a collection of eight vertices, a collection of six planes or others, for this ...
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How to determine a MTV's direction for a given object in Separating Axis Theorem?

I have irregular polygons A and B. They intersect and I want to move the polygon A from the polygon B to get rid of the intersection. I have a MTV. MTV is a magnitude (a minimal overlap of polygons' ...
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2answers
72 views

How to use separating axis theorem to allow for sliding along walls

I'm making a 2D platformer game and using the separating axis theorem for collision detection, but I want the player to be able to walk along the ground and slide on walls and other stuff and I can't ...
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0answers
131 views

Getting false positives with SAT

I've been trying to get proper collision detection with SAT in 3D. I started of with this post: How many and which axes to use for 3D OBB collision with SAT. I've been trying to get the right axis to ...
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What is the correct way to implement sweeping SAT?

I am trying to implement Sweeping SAT like described here http://realtimecollisiondetection.net/files/levine_swept_sat.txt and I have already seen the answer to this question Finding the contact point ...
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2answers
64 views

How do I test for collisions between two concave shapes decomposed into collections of convex polyhedra?

I am using convex decomposition with SAT (separating axis theorem) and I generate two arrays of convex pieces, How do I submit my arrays to my collision detection method which only takes two arguments....
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1answer
101 views

Calculate bounce and friction after a projection-based collision

According to the N Tutorials, after a projection-based collision (i.e, adding a minimum translation vector to an object's position in order to bring it out of collision), bounce and friction are ...
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1answer
111 views

Separating Axis Theorem and rotated objects

Quick question which hopefully won't require thralling through my code. I have a working implementation of SAT for 3D collision detection but I'm having some problems with dealing with rotated ...
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2answers
308 views

Separating Axis Theorem is inconsistent

I recently implemented the SAT algorithm into my 2D game and at first it appeared to be working fine. However, when I move around and rotate the character in and out of the wall tiles, there are some ...
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1answer
321 views

2D SAT Collision - Triangle and Square Problem

So I was just doing an example 2D SAT collision detection problem on paper when I encountered something unexpected. I ran the algorithm on a triangle and a square, and the result of the algorithm was ...
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0answers
67 views

Seperating Axis Theorom For Collision Detection issues

I have been attempting to use the SAT test to determine whether two of my convex meshes are colliding, however I've encountered are rather strange issue. The algorithm does determine whether the ...
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1answer
176 views

How to get a translation vector in a certain direction? SAT

I'm using the seperating axis thereom for discrete collision detection. I have code to find the minnimum translation vector (or distance) to seperate two shapes but how can I adjust it to get a vector ...
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0answers
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(Java2D) SAT Collision only works when shape is placed initially so it will collide

I'm working on a small 2D top down racing game and I'm trying to implement SAT collision into my game to detect collision between cars. So, I made a small little Java2D program to test the algorithm ...
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1answer
278 views

Separating axes theorem problem

I´ve been following this tutorial : http://www.dyn4j.org/2010/01/sat/ to help me understand and implement the SAT for collision detection in my games as I want to add a support for polygons. However, ...
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68 views

My collision detection code gives incorrect result

I am trying to use Separating Axis Theorem to check for collision between two shapes, but it's not working correctly. It's giving all incorrect results. The problem is in the collision-checking ...
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2answers
345 views

How to resolve collision when both of the intersecting bodies were moving?

Suppose there are two quadrilaterals A and B. A is stationary but B is moving. They collided. Now B is inside A. To check if they are intersecting I can use 2d separating axis theorem (SAT). To ...
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2answers
348 views

How to get the point of collision in Separating Axis Theorem?

I'm interested in the relatively precise point (not line) of collision for calculating angular velocity on impact for use in a impulse calculation. At first I thought, perhaps naively, that I could ...
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0answers
164 views

Game Physics: Calculating a collision response using the Separating Axis Theorem?

I am working on a project in which I have implemented the Separating Axis Theorem to detect collisions between objects. My current collision response is an object that contains whether it is ...
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2answers
197 views

Zero vector test in projection intersection test in SAT

I stumbled across this implementation for a projection intersection test to use in a SAT test: ...
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1answer
64 views

My polygons only register a collision if they are the same shape and directly over top of each other

I'm trying to learn about 2d polygon collision detection/handling and have ran into a snag. After running through lots of tutorials and sample code I've attempted to implement my own polygon class ...
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1answer
268 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 ...
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0answers
598 views

Calculating Minimum Translation Vector in Separating Axis Theorem based algorithm

In the 2D SAT collision determination algorithm, you project the convex polygons onto each potential separating axis. Supposing the polygons intersect, from what I understand, the axis for which the ...
3
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2answers
807 views

How to calculate faces involved in collision (Separating Axis Theorem)

I have a game engine created in javascript (https://jsfiddle.net/4gqsq8wf/) which uses collision detection via the Separating Axis Theorem. Currently, it does not have any means of resolving velocity ...
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0answers
687 views

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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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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0answers
139 views

2D Polygon Collision push direction with large polygons

I have a collision detection/resolution implementation that uses the Separating Axis Theorem. Detection and such works perfectly fine, as well as resolution for most objects/shapes in my game. ...
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1answer
280 views

Separation of axis theorem implementation at normals

This might be more of a math question, but it relates to the development of a simple physics engine I am trying to create. I have been stumped on this for about a week now, and have been unable to ...
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1answer
183 views

What are “supporting points” in the context of the SAT?

I am currently implementing a separating axis theorem collision response. It can be used by oriented bounding boxes and axis-aligned bounding boxes. So far I have covered face-something contacts. I ...
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2answers
349 views

Vertical Collision Detection, Falling Through Ground

After much work trying to learn collision system theory and apply it, I've got my collision system working for the most part. The player can collide horizontally with no issue, sliding against walls, ...
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2answers
838 views

Slopes vs. Rectangles: Different Collision Points

My platformer has both rectangular tiles and right-triangle slopes with rectangular hitboxes. My sprites are also rectangular. Collision with only rectangular tiles works well. Even if there are ...
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1answer
323 views

Calculating distance for Gauss Map optimized SAT

There's an optimization method for the separating axis test in 3D that uses Gauss Maps to discard certain redundant axes from the set of axes that need to be tested generated by edge-edge cross ...
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1answer
169 views

Resolving penentration after collision using Separating Axis Thereom

I implemented collision detection in my game using SAT. The detection works, but I'm trying to use the algorithm to figure out the penetration vector of the two OBBs and push them apart (before doing ...
3
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2answers
1k views

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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1answer
389 views

Separating axis Theorem rotation issue

I made a post yesterday to see if anyone could understand my problem. However I did not receive much guidance, probably because my question was not clear. I have worked on it a little more and ...
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0answers
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Separating Axis Theorem Issue

I am trying to create a 2d top down shooter using DirectX 11 (Windows 8 Store) and I am trying to implement OOBB collision using the Separating Axis Theorem. However I appear to have run into an ...
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2answers
473 views

SAT - How to find Shortest line between two static convex 2D Polygons?

RI have a pretty standard SAT algorithm that seems to successfully be detecting collisions but now I am looking for some assistance in finding the shortest line between 2 separated Polygons. I ...
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2answers
324 views

Collision detection circle-segment-segment

I've already implemented collision detection in my game loosely following this tutorial, which works great, but I realized there's one major flaw. The player and the enemies are circles, while the ...
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1answer
699 views

Separating axis theorem with multiple polygons?

I am attempting to implement the separating axis theorem in C#. I have a function that can calculate the minimum translation vector between two polygons. However, I can't seem to create a function ...
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0answers
58 views

Calculating contact points with SAT [duplicate]

After detecting a collision between two convex shapes by using separating axis theorem and calculating MTV. How can I calculate the contact points?(for applying torque to the rigid body).
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1answer
188 views

AABB SAT code detects collision wrongly [closed]

I've been having trouble getting my SAT code working using AABBs, and I've been trying to find a solution but, I'm scratching my head. For some reason, it detects collisions very wrongly, as shown by ...
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1answer
560 views

Problems about oriented bounding boxes collision detection

I get a question for the following code which detects if two OOBs collide by SAT. The OBBs struct is also listed below. ...
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2answers
4k views

2D Rectangle/Circle Continuous Collision Detection

I'm looking for a fast 2D continuous collision detection algorithm for circles and rotated rects. It needs to determine the time of collision. Both shapes may be moving at high speed, so the ...
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1answer
1k views

AABB vs OBB Collision Resolution jitter on corners

I've implemented a collision library for a character who is an AABB and am resolving collisions between AABB vs AABB and AABB vs OBB. I wanted slopes for certain sections, so I've toyed around with ...
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2answers
598 views

Collision detection with multiple polygons simultaneously

I've written a collision system which detects/resolves collisions between a rectangular player and a convex polygon world using the Separating Axis Theorem. This scheme works fine when the player is ...
2
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1answer
148 views

Robust “soft” platform collision using SAT

We'll start with the questions, then a pile of background: How do you rigorously and thoroughly define "soft collision" of the Mario-esque type (if I start above, or in a jump my feet apex above a "...
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1answer
1k views

Simple 3D collision detection for general polyhedra

I have correctly set up a SAT system. I now need to determine a simple, fast, and general purpose collision detection mechanism to identify the collision points. These points will then be used to ...
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1answer
432 views

SAT test for Triangle - convex hull

I'm having real trouble resolving this issue with triangle-convex hull SAT test intersection. The problem is as follows: Misses are detected accurately enough: Clear miss I have not found a ...
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1answer
4k views

Separate axis theorem applied to AABB misunderstood

I'm trying to implement a collision system for a 2D platformer using the SAT algorithm. For what I need, my implementation only handles AABB's, I followed the instructions given here. It works, there ...
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1answer
599 views

Separating axis theorem implementation flaky minimum translation vector based on triangle orientation

I've implemented some collision detection using separating axis theorem. Works fine for axis-aligned rectangles and two out of four possible right triangle orientations. For some reason when the ...
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3answers
3k views

Narrow-phase collision detection algorithms

There are three phases of collision detection. Broadphase: It loops between all objecs that can interact, false positives are allowed, if it would speed up the loop. Narrowphase: Determines whether ...