A technique for using rays to determine points of intersection. Often used in lighting simulation.

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How to raycast select a scaled OBB?

I have the OBB picking code to select an OBB with code inspired from Real time Rendering 3 and opengl-tutorial.org. I can successfully select objects that have been moved or rotated. However, I cant ...
2
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1answer
175 views

Detect obstacles in path on a tile-based map

I'm creating a 2d game with a tile-based map, but smooth movement. I currently use A* in combination with some other tricks for pathfinding, and one issue what I've been dealing with is getting the ...
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1answer
1k views

How to find objects in front of my player

I am trying to find an object that is in front of my player sprite using the following code RaycastHit2D hit = Physics2D.Raycast(transform.position,Vector2.right,EnemyLayer); //EnemyLayer is the ...
2
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1answer
496 views

The correct way to transform a ray with a matrix?

Playing with XNA Triangle Picking Sample I found out that it does not work well if you scale the world matrix of the objects you want to pick. When I dug into the implementation I found this comment ...
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1answer
230 views

How do I find voxels along a ray?

I am making a voxel engine, and I want to make it possible to create and destroy voxels with the mouse. I use C++ and OpenGL, so C++ examples would be best. So far, I have the camera position and ...
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1answer
194 views

Bounding Box in Monogame for mouse picking - Ray perspective

My mouse ray is screwing up precision. I don't really know how to fix it, maybe you guys can help. problem : (5.6mg gif) https://www.dropbox.com/s/v0z67afso88hsd1/perspective_ray.gif how i create ...
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1answer
256 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 ...
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1answer
670 views

How does Raycasting work in XNA Farseer and player collision?

Wanting to know how to figure out if player's bottom is colliding with object so that I could allow the player to jump. I was trying to use OnCollision but was referred to ray-casting, I looked ...
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1answer
2k views

Platformer raycast collision detection

I'm using Unity to create a 2D platformer. For collision detection, I'm using raycasting to detect any possible collisions with specific collision layers, and adjusting the desired delta x & y ...
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2answers
196 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 ...
5
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1answer
306 views

How can I ensure field of view symmetry in a Roguelike?

I'm working on a Roguelike, and for it I've created a ray-tracing/casting field-of-view (FoV) algorithm that consists of plotting Bresenham lines to every point in a solid circle. It's artifact free ...
2
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3answers
521 views

Strategy for detecting hits from a “cylinder ray”?

I was planning on using ray casting for collision detection in my game. However, when I use an attack similar to this: (which would project something like a cylinder), how would I go about ...
2
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1answer
375 views

Ray picking and bounding boxes in Java

How do I check which bounding boxes (of different types) a ray, sent from the camera through the mouse-click coordinates, intersects with first in Java (and where)? I have arrays (box_X, box_Y, box_Z, ...
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0answers
208 views

Block picking / ray casting through 3d blocks always slightly off

I've been working on adding a line-of-sight/ray-tracing system to my 3d block-world game. I've tried several different methods and they all work fairly well. At the moment I'm using something similar ...
2
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1answer
243 views

Are ambient, diffuse and specular light or material properties?

Are ambient, diffuse and specular properties of light or material? I am doing ray casting in OpenGL, I've managed to create lit sphere using formula I = L Ka + L Kd (n . l) + L Ks (r . v)^n but I ...
3
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1answer
835 views

box2d raycast filter category

I am trying to filter a category in my ray casting (jBox2D within libGDX), which should return the closest object that does not belong to the category LEVEL0. I've tried a plethora of approaches, but ...
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0answers
394 views

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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1answer
139 views

How to place an object so that it does not overlap the objects in my scene?

In my game, the user has to click at a point to place an object (mesh). I can cast a ray and find the horizontal point where the object can be translated and then attached to rootNode to display it. ...
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0answers
114 views

Corona SDK Live RayCasting [closed]

I'm looking for help involving rayCast in Corona SDK. If you haven't see it here's a link talking about it along with a demo. WEll in the demo you tap on a space and the ray is recasted and bounced if ...
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1answer
212 views

Volume raycaster problems HLSL

Hi this is my first question here so if I fail to include some necessary piece of information please dont rip my head off. ^^ I can't seem to get my volume raycaster to workt properly. I've been ...
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3answers
574 views

How to check whether a ray cast hits a specific side of an object?

I am using Ogre3d to develop a 3d simulation/game. One task is to determine whether the user has focused the camera on a specific object. So I cast a ray from the camera to what is currently in the ...
0
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1answer
120 views

3D drawing precision problem. XNA

I have a simple scrolling camera positioned 2000 units about the 3D 'floor' that moves forward by 1 unit every frame and looks down on the floor at a point that also moves forward by 1 unit every ...
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1answer
499 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 ...
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1answer
136 views

Ray picking gives inversed results

I'm trying to do a simple ray picking implementation to allow a user to select a cell in a grid rendered in 3D. I'm almost there, but I've ran into an issue which I can't seem to solve. Consider the ...
7
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3answers
4k views

How do I implement occluded lighting in a block-based 2D game?

I want to have 2D lighting that can be blocked by in-game objects. My game has a top-down view and all game objects are described by rectangles. Let's say I have a 10x10 world and I place a light at ...
8
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2answers
483 views

Diagonal line of sight with two corners

Right now I'm using Bresenham's line algorithm for line of sight. The problem is I've found an edge case where players can look through walls. Occurs when the player looks between two corners of a ...
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1answer
238 views

Quick 3D sight calculation algorithm

I have a tile based board game where units move in 3D space on a 2D isometric view. When calculating attack tiles for a unit, how do I verify that they aren't shooting through a wall or a level too ...
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1answer
596 views

Ray Tracing in 3D - generating a ray

A ray is shot from the camera eye to the camera screen at point (i,j) how do I get the coordinates of that point in 3D world coordinates? The best I could find online is for point S S = Q + au + bv ...
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3answers
211 views

Keeping raycast on the same level

I want my raycast to end at certain height(red line). But as the game is 3D and the camera rotates I can't use a fixed magnitude. What I thought was a stroke of genius, I figured I'd project the ...
0
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1answer
443 views

Displaying sprites in a 2.5D raycasting engine

I'm developing a raycasting engine like the one used in DOOM, Wolfenstein 3D, etc. My engine is capable of correctly displaying walls and textures on walls, but I'm stuck at sprites rendering. Given ...
5
votes
1answer
3k views

More efficient way to implement Line of sight on a 2d grid with ray casting?

Consider a 2d grid of tiles, and an approximated sphere of coordinates - centered on the player - that represents line of sight. The goal is to block the line of sight beyond obstacles (ie walls). ...
13
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4answers
4k views

Cast ray to select block in voxel game

I am developing a game with a Minecraft-like terrain made out of blocks. Since basic rendering and chunk loading is done now, I want to implement block selecting. Therefore I need to find out what ...
2
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1answer
1k views

Raycasting “fisheye effect” question

Continuing my exploration of raycasting, I am very confused about how the correction of the fisheye effect works. Looking at the screenshot below from the tutorial at permadi.com, the way I ...
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0answers
93 views

Performance issues with visibility detection and object transparency

I'm working on a 3d game that has a view similar to classic isometric games (diablo, etc.). One of the things I'm trying to implement is the effect of turning walls transparent when the player walks ...
4
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1answer
2k views

Raycasting tutorial / vector math question

I'm checking out this nice raycasting tutorial at http://lodev.org/cgtutor/raycasting.html and have a probably very simple math question. In the DDA algorithm I'm having trouble understanding the ...
8
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3answers
1k 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 ...
3
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1answer
1k views

Problems implementing a screen space shadow ray tracing shader

Here I previously asked for the possibility of ray tracing shadows in screen space in a deferred shader. Several problems were pointed out. One of the most important problem is that only visible ...
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vote
2answers
985 views

Raycasting mouse coordinates to rotated object?

I am trying to cast a ray from my mouse to a plane at a specified position with a known width and length and height. I know that you can use the NDC (Normalized Device Coordinates) to cast ray but I ...
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2answers
398 views

Wavefront mesh: determine which face a point belongs to?

I have a 3D mesh Wavefront .obj file. Is there any algorithm that takes an arbitrary point coordinates as input and determines which face of the mesh that point belongs to ?? The mesh is rendered on ...
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1answer
952 views

Ray casting on a mesh using libgdx [closed]

I'm trying to perform ray casting on a mesh using libgdx. I found this code sample and it misses some explanations. What do these vectors stand for? What is globalIntersection and localIntersection?
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1answer
179 views

Looking for a library to create a grid based first person game online

Before I go and build it myself, I have been looking for a library that may help making a grid based first person view similar to: https://www.youtube.com/watch?v=GwmZoCFd4Us I plan to make a web ...
8
votes
1answer
3k views

Why doesn't Unity's OnCollisionEnter give me surface normals, and what's the most reliable way to get them?

Unity's on collision event gives you a Collision object that gives you some information about the collision that happened (including a list of ContactPoints with hit normals). But what you don't get ...
2
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1answer
378 views

OpenGL 3+ Range Picking

How do I perform range picking in the latest OpenGL version? By range picking I mean selecting all objects which are picked using a selection rectangle, like in an RTS game. For single object picking ...
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vote
2answers
4k views

How to handle 3D collisions using raycasting (with a reflection vector?)

I'm making a game using THREE.JS, and I want my character to walk on the terrain, and collide with static 3D objects (=AABB boxes) that are on that terrain. The problem is: THREE.JS has only a ...
1
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1answer
2k views

Raycasting Collision Detection

I need to check for collisions when firing a bullet, but I have a few questions first. My game is 2D and tile based, it also uses the XNA framework. From what I've read raycasting or continuous ...
0
votes
1answer
137 views

Is it safe to cast my 2D points to 3D points for a library which only takes Vector3s?

I need to cast a ray in 2D space for bullet collision detection, but the Ray.Intersects method requires a BoundingBox which uses vector3's not vector2's. My question is should I just ignore the Z ...
2
votes
1answer
530 views

What is an easy way to work subsurface scattering into a raycaster?

I've got some neat effects with path tracing: I want to add in an ability to do subsurface scattering, but I'm unsure of the general algorithm. With path tracing, it's: foreach pixel: trace( ...
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2answers
520 views

What mathematics would I need to know in order to build a 2.5D raycasting engine

I realize this is a fairly common-type question, but I've been studying Maths in my spare time, fairly slowly at that, and I really want to develop a raycasting engine like the original DOOM. I know ...
5
votes
1answer
3k views

Finding if a point is inside of a mesh (Point-in-polyhedron)

How can I find if a point (Vector3) is inside of a mesh? Would this work for both concave and convex objects? I read somewhere that if you raycast in both directions of every axis (X, -X, Y, -Y, Z, ...
0
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2answers
892 views

3D collision detection with meshes using only raycasting?

I'm building a game using WebGL and Three.js, and so far I have a terrain with a guy walking on it. I simply cast a ray downwards to know the terrain height. How can I do this for other 3D objects, ...