kandi X-RAY | QuadTree Summary
kandi X-RAY | QuadTree Summary
Very usefull and for game development this QuadTree implementation will help you create an efficient collision detection System.
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QuadTree Key Features
QuadTree Examples and Code Snippets
Trending Discussions on QuadTree
Any "W" refers to half-width and any "H" refers to half-height. Any "X" and "Y" refers to the center of a rectangle aligned with the co-ordinate axes.
I am attempting to write some general purpose quadtree code for use in physics simulations and game design. At first it was returning ALL points in the contents of a quadtree that was completely enclosed by the search region. After adding a bunch of print() statements to illuminate the process I managed to solve that problem but now I have a new one I can't seem to figure out. For some reason when I query the quadtree for the "Placeables" within a rectangular region I either get a totally correct result, but more often than not I get nothing returned at all. Placeables are defined as follows:...
ANSWERAnswered 2021-May-12 at 06:13
Wow, this was a difficult problem to find (at least, I hope I solved it).
The problem is with your definition of
Gource project. Compile error comes when doing
g++ -std=gnu++0x -Wall -Wno-sign-compare -Wno-reorder -Wno-unused-but-set-variable -Wno-unused-variable -g -O2 -pthread -pthread -o gource src/gource-action.o src/gource-bloom.o src/gource-caption.o src/core/gource-conffile.o src/core/gource-display.o src/core/gource-frustum.o src/core/gource-fxfont.o src/core/gource-logger.o src/core/gource-mousecursor.o src/core/gource-plane.o src/core/gource-ppm.o src/core/gource-quadtree.o src/core/gource-regex.o src/core/gource-resource.o src/core/gource-sdlapp.o src/core/gource-seeklog.o src/core/gource-settings.o src/core/gource-shader.o src/core/gource-shader_common.o src/core/gource-stringhash.o src/core/gource-texture.o src/core/gource-png_writer.o src/core/gource-timezone.o src/core/gource-vbo.o src/core/gource-vectors.o src/gource-dirnode.o src/gource-file.o src/formats/gource-apache.o src/formats/gource-bzr.o src/formats/gource-commitlog.o src/formats/gource-custom.o src/formats/gource-cvs-exp.o src/formats/gource-cvs2cl.o src/formats/gource-git.o src/formats/gource-gitraw.o src/formats/gource-hg.o src/formats/gource-svn.o src/gource-gource.o src/gource-gource_shell.o src/gource-gource_settings.o src/gource-key.o src/gource-logmill.o src/gource-main.o src/gource-pawn.o src/gource-slider.o src/gource-spline.o src/gource-textbox.o src/gource-user.o src/gource-zoomcamera.o src/tinyxml/gource-tinyxmlerror.o src/tinyxml/gource-tinystr.o src/tinyxml/gource-tinyxml.o src/tinyxml/gource-tinyxmlparser.o -lGL -lGLU -lfreetype -lpcre -lGLEW -lGLU -lGL -lSDL2_image -lSDL2 -lpng15 -lboost_system -lboost_filesystem src/gource-gource_settings.o: In function
boost::filesystem::path::path(boost::filesystem::directory_entry const&, boost::enable_if::type>, void>::type*)': /usr/include/boost/filesystem/path.hpp:139: undefined reference toboost::filesystem::path_traits::dispatch(boost::filesystem::directory_entry const&, std::__cxx11::basic_string&, std::codecvt const&)' collect2: error: ld returned 1 exit status
Build enviroment use libboost_filesystem.so.1.53.0....
ANSWERAnswered 2021-May-05 at 11:50
Your library has this symbol:
I have a boids flocking simulation setup. It originally worked by having every boid loop through every boid so that they all constantly know where each other are at in order to tell if they are close or far away, but then I switched to a quadtree design so that boids only have to loop through boids that are actually nearby. However, it has made virtually no improvement to the simulation's FPS. It's as if I'm still looping through every single boid.
ANSWERAnswered 2021-May-02 at 13:02
The reason why you are not seeing obvious performance gains from the Quadtree is because of the nature of your simulation. Currently, the default separation causes a large number of boids to "converge" to the same position.
Lots of objects in the same position is going to negate possible speedups due to spatial partitioning. If all the objects are in the same or near position, boids in the area a forced to check against all other boids in the area.
You can demonstrate to yourself that your Quadtree is working by watching or profiling your application with its default settings. Now turn separation up to maximum. You will see visually, or through profiling, that as the boids spread out more evenly, the FPS increases significantly. This is because the Quadtree can now prevent computations thanks to its spatial partitioning.
You can see how performance is increased in the second image. Also note, that the conjecture by another commentor that it is the construction of the Quadtree (
insert) that is taking up all the time is wrong.
While in some applications you may be able to update a Quadtree as things move around, since in this simulation every constituent moves every frame, reconstructing the Quadtree from scratch is less work, then taking every object out and reinserting it into its new position.
The advice to skip square-rooting and just use the distance-squared is good though as this will get you a bit more performance.
After a quadtree is fully created, why does comparison operation (for collision detection of
n objects) take linearithmic
n log(n) time? The nodes are recursively split by region/quadrant, and the search will scan down the tree, pruning off paths that aren't within the search coordinates, eventually finding or not finding target nodes within the bounds of the collided node. Each operation is comparing a divided partition
n, which seems like
log(n) time, not
ANSWERAnswered 2021-Apr-14 at 13:29
To find all collisions of
n objects (as well as to reveal any one collision in the worst case), one should perform about
n actions - check a vicinity of every object.
Every such checking, as you wrote, takes
O(logn) time, so overall time reaches
wsplit = 1 I want to split base on width, else height.
threshold will be defined should split or not.
tx, ty will be the left top coordinate of the Quad.
sx = Width of the original image
It will work like...
ANSWERAnswered 2021-Mar-28 at 20:30
It looks like the issue is that you are forgetting to initialize all variables. You should ensure you initialize all of the variables in both the
if and the
I have an old doughnut hybrid pie chart/bubble chart combo working on d3v3.
//doughnut bubble chart v3 https://jsfiddle.net/ajevh5wf/...
ANSWERAnswered 2021-Feb-01 at 00:27
Many things have changed from v3 to v4, like d3.pack() instead of d3.layout.pack(), and having to import the "ease" module and reference d3.easeSin instead of 'sine'. Once you take care of all these little differences, your code works: https://jsfiddle.net/dc6eugtn/1
Here's the relevant section of changes:
I've been working on implementing a quadtree based LOD system. I'm using Pyglet as a python binding for OpenGL and I'm getting some weird behavior, I'd like to know if I'm doing something wrong.
Setting up my buffers: (input data are leaves of a quadtree to be decoded in the vertex shader)...
ANSWERAnswered 2021-Jan-30 at 08:43
If the type of the attribute is integral (e.g.
uint) you must use
glVertexAttribIPointer instead of
glVertexAttribPointer. Focus on
I and see
glVertexAttribPointer(0, 1, GL_UNSIGNED_INT, GL_FALSE, 0, 0)
I have a QuadTree but the insert method is not working like I want it to. Right now it only inserts in the first intersecting quad it sees. The aim is that all nodes are inserted in all the quads its intersecting with. For example: when a node is on the border of two quads, it is inserted in both quads. Can somebody help me to get the insert method to where it is inserted in all intersecting quads?
This is my current implementation:
This is the call to insert the nodes:...
ANSWERAnswered 2021-Jan-19 at 13:46
else if to ensure a item is inserted to each of its subnodes.
I've got a converted d3v4 bubble chart, but there used to be so much more features like gravity/charge and collision detection for these kind of things in d3v3. When the chart loads - I want to see a consistent/movement of the bubbles like watching frog spawn in a pond - they get close to each other through gravity - but have repellant/charge type properties. The bubbles also need to try and keep away from the edge.
Here's what I'm looking for with v3:...
ANSWERAnswered 2021-Jan-04 at 03:29
there used to be so much more features like gravity/charge and collision detection for these kind of things in d3v3
D3v4+ has better functionality than d3v3 when it comes to force layouts. But, ironically, looking at the fiddle you shared, you actually aren't using a force layout to actually place your nodes. Try changing the gravity or charge to wildly different values - nothing changes, you never pass the nodes to the simulation with
That said, the force simulation is providing an alpha value, calling the tick function repeatedly, etc, but there is no direct interaction between the nodes and the force simulation. All positioning is done manually in the tick function. The force could be replaced with a timer to achieve the same result here.
This suggests you are asking the wrong question, instead of
- How do I upgrade my layout to v4
It is likely:
- How do I incorporate my custom positioning functions into d3v4's force layout.
To start with, let's look at your two positioning forces:
- The collision detection in the fiddle is built into d3v4 (d3.forceCollide), the code is very similar to what you have used.
- Mutli-foci point force directed graphs are done in a similar way as they were in d3v3. Below I use a single focal point with forceX and forceY, which matches your fiddle.
Here's a simplified example of what you have which is much easier to work with here:
I am trying to build a data visualization with d3 and I am running into the following error in my console....
ANSWERAnswered 2020-Dec-08 at 17:00
The problem indicates an SVG element group ( tag ) has NaN for position coordinates.
I see a problem maybe here in your code :
Try to get rid of the em value and use raw numbers.
I'm not certain it will solve your problem though, if you could post the error in the console and the element it applies to I could help you more.
No vulnerabilities reported
You can use QuadTree like any standard Java library. Please include the the jar files in your classpath. You can also use any IDE and you can run and debug the QuadTree component as you would do with any other Java program. Best practice is to use a build tool that supports dependency management such as Maven or Gradle. For Maven installation, please refer maven.apache.org. For Gradle installation, please refer gradle.org .
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