A technique for using rays to determine points of intersection. Often used in lighting simulation.
2
votes
1answer
85 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 ...
2
votes
1answer
99 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 ...
0
votes
0answers
24 views
bounding box of objects reflected in a surface
I'm interested in a subset of ray-tracing functionality. Specifically, I have a mirror surface (specified as some bidimensional surface, as of yet with no specified implementation, maybe some ...
0
votes
0answers
63 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 ...
0
votes
1answer
114 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. ...
0
votes
0answers
123 views
LWJGL Mouse picking when camera rotated
I have third person camera in my game and I have mouse picking which works not so good. It works good only when yaw rotation is lesser than ~75 if yaw is greater than 75 then it fails.. Here is video ...
2
votes
0answers
48 views
Corona SDK Live RayCasting
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 ...
0
votes
1answer
120 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 ...
0
votes
0answers
79 views
Android Screen-World Raycasting using GLU.gluUnProject method glitch?
I had been using GLU.gluUnProject to translate coordinate from 2d screen to world.
I found it odd and frustrating because for some reason using the method results in
unpredicted values.
I included ...
4
votes
3answers
214 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
votes
1answer
72 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 ...
0
votes
1answer
235 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 ...
-1
votes
1answer
78 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 ...
3
votes
2answers
826 views
How to ray cast 2D light in a block-based game
I want to use 2D lighting that can be blocked by in-game objects. My game is block-based and has a view from the top of the flat world. Now lets say I have a 10x10 world and I place a light at 1x1 and ...
7
votes
2answers
280 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 ...
0
votes
1answer
95 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 ...
1
vote
1answer
178 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
...
0
votes
3answers
110 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
votes
1answer
234 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 ...
0
votes
0answers
52 views
Reading text-coord from a multitextured mesh
Ive been trying different ways to create a ray method that gives me back whatever texture is on a mesh by using the xna triangle picking sample as a starting point, but
theres just one last thing I ...
3
votes
1answer
1k 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).
...
8
votes
4answers
1k 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 ...
1
vote
1answer
428 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 ...
1
vote
0answers
75 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
votes
1answer
607 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
votes
3answers
592 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 ...
1
vote
1answer
703 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 ...
1
vote
2answers
444 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 ...
0
votes
2answers
218 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 ...
-2
votes
1answer
446 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?
1
vote
1answer
129 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 ...
6
votes
1answer
973 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
votes
1answer
315 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 ...
1
vote
2answers
2k 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
vote
1answer
1k 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
125 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
271 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( ...
1
vote
2answers
373 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 ...
4
votes
1answer
776 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
votes
2answers
549 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, ...
3
votes
1answer
311 views
3d Picking under reticle
i'm currently trying to work out some 3d picking code that I started years ago, but then lost interested the assignment was completed (this part wasn't actually part of the assignment).
I am not ...
1
vote
1answer
273 views
How to calculate the viewing cone radius at a distance in raymarching?
I'm "raymarching distance fields" (proper lingo: sphere-tracing) in GLSL. To implement cone-marching atop of it (and also to minimize the number of raymarching steps regardless of whether ...
1
vote
1answer
1k views
Optimized algorithm for line-sphere intersection in GLSL
Well, hello then!
I need to find intersection between line and sphere in GLSL. Right now my solution is based on Paul Bourke's page and was ported to GLSL this way:
// The line passes through p1 and ...
11
votes
1answer
741 views
How can I draw an arrow at the edge of the screen pointing to an object that is off screen?
I am wishing to do what is described in this topic:
http://www.allegro.cc/forums/print-thread/283220
I have attempted a variety of the methods mentioned here.
First I tried to use the method ...
0
votes
1answer
3k views
OpenGL ES 2.0 gluUnProject
I've spent more time than I should trying to get my ray picking program working. I'm pretty convinced my math is solid with respect to line plane intersection, but I believe the problem lies with the ...
7
votes
1answer
562 views
Skewed: a rotating camera in a simple CPU-based voxel raycaster/raytracer
TL;DR — in my first simple software voxel raycaster, I cannot get camera rotations to work, seemingly correct matrices notwithstanding. The result is skewed: like a flat rendering, correctly rotated, ...
2
votes
4answers
148 views
Ray Triangle Intersection issue
I'm trying to perform ray triangle intersection on a mesh made of triangles. The below code seems to work fine but only about 50% of the time. The ray often gets into positions where no intersection ...
5
votes
1answer
381 views
Raymarching artifacts
I was playing with raymarching using distance fields in GLSL sandbox and got stuck with a strange problem with artifacts.
Click here and take a look at the spheres generated in corners, they have ...
3
votes
1answer
387 views
How to calculate FOV with four-walled tiles?
I'm working on a 2D tile-based game. I'm trying to calculate FOV and I've implemented walls so they don't take up an entire tile. Instead, they just take up a side of each tile. Similar to:
class ...
1
vote
1answer
2k views
Picking objects with mouse ray
I simply want to pick a few spheres in my scene using the mouse-ray. I have implemented(copied most of it but with little understanding) a ray-sphere collision code. Also I have implemented the code ...
