# Tagged Questions

The point or points at which two or more shapes cross or overlap one another.

67 views

### I need to find intersection point of a vector in an axis aligned rectangle

I need some help, I have one vector in a rectangle like following (Ops, first A2 point on the top should be A1, assume it is A1) Let's say the vector is like above It doesn't have intersection ...
178 views

### 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) ...
3k views

### Triangle-Plane intersection in 3D space

I would like to clip a triangle if its bounds lie partially out of a cube for this I guess I would need some kind of Triangle Plane intersection code, I'm not well versed with math but I do have the ...
91 views

### Best way to find line segment intersection

I need to find the point of intersection between two line segments in 2D space. I receive them in terms of both coordinates of both lines. Because they are line segments I would also need to know if ...
447 views

### Java 2D Game Hitbox Detection & Rounded Corners

I am working on a simple 2D game with Java, swing and no framework. I have a rectangular player that the user can move around. On the map are few obstacles which the player should not be able to go ...
50 views

### What is the best way to check for intersection of two bounding boxes, given a minimum and maximum Vector3 for each one

I have a BoundingBox object which holds two Vector3's (x, y, z), one for the minimum point and one for the maximum point. (-1.5 0 9 | 1.5 3 10) What is the best way to check for any intersection or ...
253 views

### How do I test for intersection between a ray and a cone?

I decided that writing a ray-tracer in my game was a brilliant idea, and so now I am looking for code to use for ray to primitive intersection tests. I have based my effort on this very nimble yet ...
19 views

### Finding intersection in CPU ray casting

I'm trying to implement a ray casting on CPU, for each pixel I have a ray. I'm reading the data which is stored in a rectilinear grid. I'm trying to find the intersection but I'm not sure how to do ...
132 views

### Section cut through (solid) geometry

I'm looking for image based (screen space) technique to render section cuts through arbitrary (solid) geometry. I found and studied image based CSG (Kirsch 05 / OpenCSG) but I found it to be perhaps a ...
82 views

### Get collision time between two moving, non uniform Axis Aligned bounding boxes

I have a problem finding the exact time of collision of two possibly moving or static objects. Both objects have AABB data (HalfExtents, Min, Max, Center vector and stuff) and a velocity vector. The ...
137 views

### Detecting if a point is inside a rectangle

I have a mouse cordinates in 2D game (x and y) and a rectangle (x,y, width,height). How to find if the point is in the rectangle? I do not have any code to post here. I'm just searching for help.
643 views

### How do I write a shader that lights up when objects are near a surface?

In this Overwatch gameplay video, the character's shield lights up white in areas that are near other objects' geometry. Note the white edges on the blue shield, near the floor, walls and pillar. ...
235 views

### Determine if Plane is seen by Camera

If I have an arbitrary plane (center and normal) or a quad (center, normal and width and height) and a camera (frustum, projection & view matrix, etc). Then how would I go about calculating if the ...
108 views

### How to find out the vertices of the polyhedron formed by the overlapping area of two rotated boxes?

What is the most efficient way for finding out the vertices of the polyhedron formed by the overlapping area of two rotated 3D boxes? If it is still confusing what I mean by "polyhedron formed by...",...
137 views

### Intersection of a Line and a Rectangle

I have to calculate the intersection of a line segment (represented by 2 points) with a rectangle. For example: Axis aligned rectangle corners: (0, 0) (100, 100) Point 1: (50, 50) Point 2: (50, ...
31 views

### Explanation of the parameters in the line intersection code

I am trying to understand a C code that moves the mesh nodes for each time step and i am totally struck on the parameters t1 and t2 please help me sorting this out. So here is what the function gets (...
39 views

### Integer ops only 3D triangle-triangle collision detection

I've a need for 3D triangle-triangle collision detection using integer math only. Unfortunately, I'm not in a position where I can use 64-bit integers (only 32-bit) and my vertex values can be larger ...
49 views

### My intersect detector isn't working

I'm trying to create rooms dinamically by creating them in random places and checking if they do overlap each other. The idea is that if the new room intersects with another one, it must be recreated ...
69 views

### Advantages of “Overlap testing” and “Intersection testing”

I have been looking for advantages and disadvantages of both techniques, but I was only able to find a few disadvantages such as: Overlap testing may fail for objects moving very fast and Intersection ...
67 views

### Cutting a 3D mesh with a 2D shape

I have a 2D image that i want to use to cut into a 3D mesh while leaving it closed (basically cut straight through it, and close it by generating vertices in both places it cut, front and back, to ...
155 views

### Rigidbody physics concept: Why translate collision shape on-the-fly instead of mutating it?

Crossposting at http://stackoverflow.com/questions/29993547/rigidbody-physics-concept-why-translate-collision-shape-on-the-fly-instead-of-m I've spent some time going through physics engine's ...
299 views

### 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, ...
100 views

### How to represent ray and line segment in parametric form?(Visibility)

I am trying to implement this algorithm but am not sure how I am supposed to represent my ray and my line segments(walls). For the r_px/r_py do I just use the position of the light? For the r_dx/...
1k views

### Collision/Intersection of (2D) Ray to Line Segment

Given a ray (r0, r1) and a line segment (a, b), I need to calculate the normal of the line segment based on the direction of the ray. For example, in the following picture: The correct normal given ...
1k views

### Segment-Cylinder intersection

What is the complete code (C#, pseudo, does not matter) for calculating the resulting segment (or its absence) for the intersection of asegment and a cylinder? The segment is defined by Vector3(x,y,z)...
8k views

### How do I find the intersections between colliding circles?

I want to find whether 2 circles with radii r1 and r2 intersect, and if so, where they do so. Is there a simple solution?
59 views

### Displaying intersection by removing vertices

I am using WPF, using the MeshGeometry3D class to build up my model. I have 2 pipes intersecting each other, and I would like to remove the region of intersection (meaning erase the portion of pipe 1 ...
291 views

### Intersection between moving circle and some squares

I'm developing a 2D game made of squares. What I need to do is check if a circle collides with any of the squares as it moves. I have a raycast function to check the same idea, but using a point. I ...
2k views

### How to calculate ray polygon intersection? [duplicate]

I'm in a class where we are creating a ray tracer from the ground up in C++. I'm at a point where I can't seem to wrap my head around the math that is required to calculate the point at which a ray ...
117 views

### Warp GameObject Size When Entering/Leaving Area

Below I have an image describing the desired functionality I am going for. Let's say you control a square and when you move this square into a given area, any part of your rigidbody/model inside of ...
563 views

### How do I find the closest points(thereby forming a polygon) enclosing a particular point?(see image)

I am working with a game engine, and my task is to add code for simulating fracture of rigid meshes. Right now I'm only working on breaking a cube. I am using Voronoi's algorithm to make a (...
540 views

### Explain this line segment intersection code

I've been reading this article on pathfinding over polygon meshes using line-of-sight, and in the article are several code snippets. One of them, the one I'm trying to understand, is a simple function ...
392 views

### Checking if a vector is contained inside a viewing frustum

I have a three dimensional pyramid given by four vectors a, b, c, d and want to test if a given vector x is inside that region or not. Here is an image: A related question can be found here: 2D ...
772 views

### How can I remove the view and projection matrix from ray position to get only the ray model?

I've got a little problem with my picking module and I need your help. I have a method to project a ray from the camera to a fixed point when I click somewhere. The computed ray looks good, it go to ...
120 views

### Precalculating timespan of bullet collision on cubic bezier curve circles?

I'm fairly new to game logics, C#/XNA (The language/library of choice) and bezier curves in general, and is stuck in my current project. I'm going to try to explain as thoroughly as I can what the ...
530 views

### Is this the correct way to detect ray-sphere intersection?

I have this java function that should return a true or false for any sphere passed to it if they intersect. However it seems to end being true a lot of the time when it shouldn't and false sometimes ...
225 views

### Thick Ray interaction with AABB

I would like to intersect a thick ray (actually a cylinder) with an AABB. The current code to perform intersection with the ray is the following. template <class RealT> bool CAABB<RealT>:...
273 views

### How do I compute the point of a triangle-ray intersection?

I have a line (the direction vector of the player) and a triangle representing the face of a model (so composed of 3 points). I can't find the mathematical operation to check if that vector is ...
359 views

### How can I compute the common points when spheres intersect?

When two spheres intersect they should share one or two points. I want to know how to compute those points? I was thinking of something like this: -check if the spheres intersect -calculate ...
227 views

### Tennis game algorithm and maths

Tennis courts are real dimensions and game is 3D Ball has position (x,y,z), speed(vx,vy,vz) and acceleration (ax,ay,az) Game has 30 fps and on each update (1/30sec) it has these properties vx +=ax; ...
808 views

### Finding Z given X & Y coordinates on terrain?

I need to know the most efficient way of finding Z given X & Y coordinates on terrain. My terrain is set up as a grid, each grid block consisting of two triangles which may be flipped in any ...
395 views

### Performing intersection testing in world's or object's space?

Am adding basic ray casting and collision detection for my game, also adding bounding volumes/collision mesh. Given that the ray is cast in world space and each mesh's node can track world ...
2k views

### How to determine which cells in a grid intersect with a given triangle?

I'm currently writing a 2D AI simulation, but I'm not completely certain how to check whether the position of an agent is within the field of view of another. Currently, my world partitioning is ...
161 views

### XNA Calculate two points of triangle with given Z

I want to calculate the two points of a 3D triangle that have a specified Z coordinate. I guess the way to do this would be to somehow create a plane which is perfectly flat with my given Z coordinate ...
133 views

### What does Rectangle.Intersect means/do?

Ok I have two rectangles one is the ball and other is the paddle. 1. if(ball.rectangle.intersects(paddle.rectangle)) y = -Math.Abs(y); and 2. if(paddle.rectangle.intersects(ball....
326 views

### Moller Tri Tri intersection

I'm done implementing Moller's tri-tri intersection routine. It gives you the location of where each triangle edge intersects the line of intersection between the 2 triangle planes: Really you get ...
387 views

### Wrong intersection: Bounding Sphere and Ray

I've got a huge problem with BoundingSpheres and Rays in XNA and I really don't know how to solve it. The problem: foreach (BoundingSphere s1 in GetCollisionHullBoundingSpheres()) if (ray....
197 views

### What to do after detecting OBB-OBB intersection

I'm using this code to detect intersections between two OBBs. The problem is that i don't know what to do after detecting it. I tried using a simple algorithm: if (collision detected) { ...