Questions tagged [picking]

A method typically used for determining what the user selected.

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35
votes
5answers
17k views

In 2D, how do I efficiently find the nearest object to a point?

I have a sizable game engine and I'd like a feature for finding the nearest of a list of points. I could simply use the Pythagorean theorem to find each distance and choose the minimum one, but that ...
9
votes
2answers
11k views

How do you determine which object/surface the user's pointing at with lwjgl?

Title pretty much says it all. I'm working on a simple 'lets get used to lwjgl' project involving manipulation of a rubik's cube, and I can't figure out how to tell which side/square the user's ...
8
votes
2answers
1k views

How do I convert a 2D movement (from mouse) to a displacement along a 3d axis?

I'm making a small 3D scene editor (that only allow to modify objects positions). Each object is draw with a 3d X/Y/Z axis : How it works : user choose an axis (X, Y or Z) by left clicking on it, ...
7
votes
3answers
743 views

How should I store dynamic game entities for efficient area-based selection?

In my 2d block-based game I'm trying to implement a data structure that would store entities entities in a way that's capable of: Direct selection based on coordinate. Iteration Iteration limited to ...
6
votes
1answer
1k views

Pixel Picking vs Raycasting

I was recently introduced to a way of picking in OpenGL known as pixel picking (or color picking). From my understanding, how this is done is that the scene is rendered to the back buffer with a ...
6
votes
1answer
190 views

Excluding Background from Color Picking

I've implemented picking based on color coding, but I don't want the background color to be pickable. Is there any way in openGL (2.x) to exclude the background color? For some reason, doing glClear(...
5
votes
2answers
2k views

Ray Picking Problems

I've read so many answers on here about how to do Ray Picking, that I thought I had the idea of it down. But when I try to implement it in my game, I get garbage. I'm working with LWJGL. Here's the ...
4
votes
2answers
1k views

How do I use D3DXVec3Unproject with D3D11?

I'm having a small issue with D3DXVec3Unproject. I'm currently using Direct3D 11 and not 10, and the signature for this function is: ...
4
votes
2answers
3k views

Get world coordinate under mouse (at a ground plane for Warcraft 3 like movement)

I want to let a unit follow the mouse like in any RTS (Warcraft 3, Starcraft, ...). For that I have a "ground plane" which is defined through 2 vectors, the X and Z axis. Now I need to get the world ...
4
votes
2answers
333 views

Tilemap Object Placement

I am looking for a way to select tiles within a bounding box for object placement within a scene/world, similar to Roller Coaster Tycoon and other simulation games. (source: tumblr.com) In the ...
4
votes
3answers
232 views

Restricting movement to 3D axis

A cube is constructed in a 3D and can be rotated to view any side. I want to be able to drag the cube to any position with the mouse while keeping the Y-coordinate the same. I used project and ...
4
votes
1answer
2k views

Opengl-es picking object

I saw a lot of picking code opengl-es, but nothing worked. Can someone give me what am I missing? My code is (from tutorials/forums) ...
4
votes
2answers
857 views

How do I pick tiles from an isometric map with slopes?

I'm looking for a way to convert mouse/screen coordinates to isometric map coordinates, with the addition that the world has slopes and cliffs, and I have to be able to tell which quadrant of the tile ...
4
votes
1answer
1k views

Picking 3D with OpenGL ES 2

I'm trying to implement picking in my framework but I don't understand how I can do this. I'm working with: OpenGL ES 2. GLM mathematic library. What I have understand, picking can be made with two ...
3
votes
2answers
7k views

How do I get mouse x / y of the world plane in Unity?

I am trying to make a tiled landscape. The terrain itself is not made from tiles but the world has a grid which I define. I would like to place boxes/rectangles which snap to this grid, at runtime, ...
3
votes
2answers
1k views

Picking 2D objects after transforming camera in XNA

I have an XNA application (a force based visualisation of some circles) that I've implemented zooming and scrolling in, thanks to this guide. Before I had the camera implemented, I had picking ...
3
votes
1answer
1k views

OpenGL picking performance: ray casting vs. color picking

I am curious of how the performance of color picking compares to ray casting. I am looking at the scenario when the mouse is clicked which means only then the scene is rendered in a backbuffer for ...
3
votes
1answer
867 views

Best way to Draw a cube for 3D Picking on a specific face

Currently I am drawing a cube for a game that I am making and the cube draw method is below. My question is, what is the best way to draw a cube and to be able to easily find the face that the cursor ...
3
votes
1answer
460 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 ...
3
votes
1answer
136 views

Triangle Picking Picking Back faces

I'm having a bit of trouble with 3D picking, at first I thought my ray was inaccurate but it turns out that the picking is happening on faces facing the camera and faces facing away from the camera ...
3
votes
1answer
775 views

Isometric tiles drawing and picking - JAVA

I'm trying to draw isometric tiles in Java and implement a tile picking system using the mouse cursor. I draw the tiles using math formulas I found and adapted to my tile textures which you can find ...
3
votes
1answer
368 views

How can I GL_SELECT from a gluPerspective-transformed scene?

I'm using JOGL to access OpenGL-methods on an old OpenGL version, because of school. I have written a method which is called before any objects are drawn. This method shows which object is picked. ...
2
votes
3answers
4k views

3D picking lwjgl

I have written some code to preform 3D picking that for some reason dosn't work entirely correct! (Im using LWJGL just so you know.) I posted this at stackoverflow at first but after researching some ...
2
votes
1answer
2k views

How to tell what part of a 3D cube was touched

I am writing a rather simple android game and I am implementing Open GL to draw a 3D cube that spins upon the X, Y and Z axis and I need to know where the user has clicked on the texture of the cube. ...
2
votes
1answer
305 views

Manual GLU.gluUnproject

Before I used GLU.gluUnproject to calculate my picking ray in my OpenGL game. Recently I switched to my own calculated matrices, and now I can forget the gluUnproject. How can I calculate the picking ...
2
votes
1answer
479 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 ...
2
votes
1answer
1k views

Ray picking - get direction from pitch and yaw

I am attempting to cast a ray from the center of the screen and check for collisions with objects. When rendering, I use these calls to set up the camera: ...
2
votes
1answer
634 views

Triangle accuracy picking for animated models in XNA

I can do picking with triangle-accuracy for non-animated models, but I also have animated models in my game. How do I do picking on animated models? I use code based on this project for animation. ...
2
votes
1answer
78 views

How can I ungrab the grabbed Object in Unity?

I modified a grab Script to my purpose, I can grab the Object and make it a parent to the character with the Key "G" but I want to let it go and detach the parent of the picked Object with "H" with ...
2
votes
1answer
2k views

libgdx collision/picking

I am trying to make something with java libgdx (2D). One thing that I can't figure it out is how to check mouse intersection with (fore example) isometric textures that are not rectangle shaped images....
2
votes
2answers
309 views

Assigning a different texture based on picking

I'm making a game using XNA. I have some simple objects like cube and sphere, and I would like to change the texture of one face of these objects based on picking. That is, when the cursor is over ...
2
votes
2answers
666 views

Unproject mouse position to tile — extremely jumpy position?

I'm trying to unproject the mouse position to get the position on the X-Z plane of a ray cast from the mouse. The camera is fully controllable by the user. Right now, the algorithm I'm using is... <...
2
votes
0answers
197 views

How can I compute a 3D picking ray from 2D screen coordinates?

I have a view matrix via glm. I want to make a ray casting system that receive an X and Y coordinate from the screen and generates a ray in the world. What math is needed? My view matrix is built ...
2
votes
0answers
364 views

How to create 3d picking ray with the cursor position

I'm new here and I'm not sure how to go about doing this. I am creating an application that is supposed to use the cursor's position in the window to perform 3d picking. The tutorials I have found ...
2
votes
0answers
1k views

Controlling 3D model with mouse XNA 4.0 C# [closed]

I am creating a 3D table tennis game and the racquet (created in Maya 2012) is controlled by the mouse. I have used picking method to control the racquet, however the cursor is not on the racquet. It ...
1
vote
1answer
283 views

OpenGL Picking: How to avoid entities?

I have a terrain and entities(npc, house...). I'm able to convert screen coordinates to world coordinates with the glReadPixels function: ...
1
vote
3answers
1k views

3D picking for mouse move event

I implemented color picking recently and I would like to use it as kind of highlight when mouse is over an object but I am concerned about performance. Color picking requires whole frame to be drawn, ...
1
vote
2answers
2k views

OpenGL 2.0 - How to swap buffers for color picking

I'm trying to reproduce color picking on iOS, following the technique described here: http://www.lighthouse3d.com/opengl/picking/index.php3?openglway2, with OpenGL ES 2.0. When the user touches the ...
1
vote
1answer
271 views

Why is texturing interfering with my ID-based picking implementation?

Today I came across a tutorial about color picking and I implemented it on my machine. But there is a problem: when I disable the texture and draw the object I want to pick with its picking color, it ...
1
vote
1answer
6k 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 ...
1
vote
1answer
52 views

How to select two different instances in Unity C#

I have 2 Balls, 2 Nodes, and 1 Hand. I can pick up a ball, send it to a Node, grab it, put it on another Node, but I can't grab any other balls. The problem is that the Ball is defined publicly in ...
1
vote
1answer
322 views

Simple mouseray picking in openGL

Ive been looking at tutorials and trying to figure out how to do basic ray-picking. But I'm stuck at figuring out what space to do the distance calculations in. What space does ...
1
vote
1answer
248 views

picking 3D objects rendered using instancing

i have a peice of code that renders a 3D image, say a cube. I require 3 cubes in in different locations, this is done using instancing and i am able to render the cube in 3 different locations. ...
1
vote
1answer
257 views

How to perform efficient 2D picking in HTML5?

I'm currently using an R-Tree for both picking and collision testing. Each entity on screen has a bounding box for collisions and a separate one for picking. Since entities may change position very ...
1
vote
1answer
50 views

Why are points adjusted using the projection and inverse view matrix during picking?

I am working on my first 3D game, which contains several vehicles placed on a board. I want to implement mouse picking of the vehicles. I found this great tutorial and used its code. But I don't ...
1
vote
1answer
141 views

Isometric tile picking algorithm not working

Starting to gamedev again and Trying an isometric game. However, all I try, I can't seem to figure out tile picking properly.. Using SFML Here's how I'm detecting the clicks and moving around a sf::...
1
vote
1answer
543 views

Heightmap terrain picking

I've implemented an OpenGL based terrain unsing a tesselation-shader for dividing each 'terrain-cell' into the desired tiles. The heightmap is uploaded to the GPU and applied on the shader. When it ...
1
vote
1answer
114 views

Picking problem with rotated view matrix

I have picking code that works, if my view matrix has no rotation (only translation). Now If I rotate my camera, picking goes to hell. I cant find whats wrong My code: ...
1
vote
0answers
52 views

Why are coordinates converted to [-1, 1] during mouse picking?

I am working on my first 3D game, which contains several vehicles placed on a board. I want to implement mouse picking of the vehicles. I found this great tutorial and used its code. But I don't ...
1
vote
0answers
461 views

OpenGL to DIRECTX RayCasting and Picking

Im doing some ray casting and picking from a book that is Open GL. I Get perfect movement on the x and y(I rotated the grid 90 so it would match the x and y. Buy when I try to put it on the the z axis,...