Tagged Questions

Numeric representation of the location of an entity in the game space. There are multiple forms of coordinate systems to cater to a variety of methods to map position.

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c++ opengl unproject not working [duplicate]

first of all, sorry for the bad english. I need to convert my mouse coordinates to world coordinates, I'm trying to use the glm unproject method. 1280x720 is the size of the window, It's hard coded ...
204 views

How can I convert between float3 and float2 in HLSL?

I want to offload some 3D calculations to the GPU without raising my requirements to DX10. Specifically, I am generating densities in 64x64x64 3D blocks, which fit nicely into 512x512 2D textures. I ...
366 views

Cartesian Coordinates & Layout [duplicate]

The way cartesian coordinations are presented and used is kinda confusing. When working with 2D the vertical axis is Y, though when working with 3D the vertical axis is Z and Y becomes the "depth" ...
257 views

Can you help me solve the paradox that has confused me about the glViewport and glOrtho functions?

suppose that I have an image that I want to apply as a texture on a geometry (at time we don't consider texture mapping but this image has a certain width and height here it is a 512x512 image) I want ...
282 views

How do I find the rotation point given a touch anchor, new position and new rotation?

I've got an Cocos2d layer which anchorPoint, position and rotation (according to http://www.qcmat.com/understanding-anchorpoint-in-cocos2d/) vary when the pinch zoom gestures. Everything works fine. ...
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World Bounds - (0, Size) or (-HalfSize, HalfSize)?

When creating a game space in which to move, draw and collide objects, is it better to have the (0,0) point, or the (0,0,0) point, be in the very center of your space, such that the bounds of the ...
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Get rotate angle using a formula

I am developing a game that is being played on a board with the top first tile having the coordinates [0,0], the next one has [0,1], second row has [1,0]... and so on (most likely this would be a ...
582 views

What am I missing? (Converting 2D mouse coords to 3D space)

I'm making a networked game which has a birds-eye view and I'm trying to convert the 2D mouse coordinates into 3D space. Right now I have a perfectly flat grid and it intends to remain perfectly flat, ...
134 views

Rotate view matrix based on touch coordinates

I'm working on an Android game where I need to rotate the camera around the origin based on the user dragging their finger. My view matrix has initial position of sitting on the negative z and facing ...
220 views

Calculating specific coordinate along a path

Let's say I have a path comprised of a sequence of points that are connect by lines and arcs. The entire path has some specific length. Let's call that length 100. What would be the mechanism to ...
222 views

Texturing spherical terrain, seemingly arbitrary distortion

I'm using this algorithm to find texture coordinates on a sphere: Wikipedia UV Coordinates I get the famous seam due to the wrong interpolation, but I also get odd distortions on certain points on ...
807 views

2d coordinates vs x/y screen positioning

I have a 2d top-down view tile map game, that generates random color tiles (water colors) as you move the character. I've been positioning elements on screen using the x/y coords (finding a way to ...
81 views

Getting correct direction of the Car [duplicate]

I am building a car racing game using the coordinate system in which I have enemies's cars and the player cars. I want to ask that what is the best way to find the the direction of enemies's cars so ...
919 views

Converting hexagon grid coordinate system

As I have been building on a RTS game based on hexagon grid built in javascript. I stumbled across a problem regarding the coordinate system. Have been trying to implement a A-star system to find ...
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How to handle scaled aspect ratio multiplayer player coordinates

I'm building a cross platform multiplayer game. I'm using pixel graphics and starting at a small 256x144 16:9 aspect ratio That gets scaled up to larger 16:9 resolutions. The graphics look ok however ...
364 views

How to flip coordinate system in Pyglet?

Is there any way I can flip the coordinate system in Pyglet vertically so that y = 0 is at the top of the screen and a higher y value is closer to the bottom? It is really confusing trying to use ...
710 views

How can I convert screen coordinates to world coordinates on the floor (when the y component = 0)?

I am using the Irrlicht Engine and would like to convert the coordinates of the mouse on the screen to the floor of my world. I am currently trying to use getRayFromScreenCoordinates() which ...
117 views

Check for obstacle [closed]

Programming language: Pseudocode In my program there will be (among others) two variables, called varX and varY. They will have only positive values, but they may be of varying length. They will ...
723 views

Choosing the correct isometric character facing direction

I am currently building a 3D game presented from a 2D isometric viewpoint. The 3D coordinates start at the top left corner of the screen with x and y increasing towards the right and bottom edges ...
121 views

Rotate Points with Object in world space

I posted this in the original stack overflow then realized that a game-dev specific one exists. I am working on personal project that requires me to have 4 points surrounding an object (1 at each of ...
244 views

Game Editor - When screen is clicked, how do you identify what coordinate you clicked?

This is a follow-up to my earlier question: Game Editor - When screen is clicked, how do you identify which object that is clicked? Something I've noticed is that picking only calculates a ray and ...
539 views

Why does handedness matter at all?

I'm really trying to understand this from a mathematical viewpoint. After all, numbers are numbers, the chirality or handedness depends on how one interprets it. Say I've three basis vectors x (1, 0, ...
653 views

Ways to “invert Z-axis” in shader-based core-profile OpenGL?

In my hobbyist shader-based (non-FFP) GL (3.2+ core) "engine", everything in world-space and model-space is by design "left-handed" (and to stay that way), so X-axis goes from -1 ("left") to 1 ("right"...
1k views

How do I calculate the z-coordinate for a perspective-camera in 2D?

I'm new to LibGDX and trying to use DecalBatch with PerspectiveCamera, simply to have Z-coordinate for my sprites, as SpriteBatch does not offer that. However, I don't know how to calculate the Z-...
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Mapping 3D object coordinates to 2D screen coordinates with perspective projection

Sort of following on from where this person was in their topic: Matrix for 2D perspective What I have at the moment is a transformation matrix that's defined as follows: http://pastebin.com/GM6BhP0R -...
4k views

What is the Box2D coordinates system?

I know that for Box2d I need to translate pixels to meters which is easy peasy. However my problem is what is the orientation of Box2D coordinates system? Is this the same as screen one (right += x, ...
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In 2d game logic, should I use pixels or world coordinates?

Currently in my game I handle the logic (collisions, movement) using pixels but I find it very limiting espiecially when thinking about variable speed. For example Box2D requires you to use ...
546 views

Converting motionevent.getx and motionevent.gety to pixel or Object coordinates in the view

I am trying to draw buttons using OpenGL I have added a Gesture Listener for the GLSurface View now i have motionevent when ever the user touches. My question is how can i convert motionevent.getx and ...
171 views

Calibration of a 6 DOF tracking device

Setting: In our facility we have a 3D laboratory with 3 large displays (two edge-to-edge on orthogonal walls, one on the ground, also edge-to-edge). Its primary use-case is exploring 3D virtual ...
266 views

SimpleOpenNI: Check if user hand is in specific area on image

Concerning our Microsoft Kinect project, we need some help. We control a robot with our movements tracked by the Kinect sensor. We display the depth image of the Kinect sensor on our screen, so we ...
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Blender 2.6: Move Mesh to X Coordinate of Another Mesh

An example: There are two planes A and B with the following median points: ( X | Y | Z ) M_A ( 3 | 2 | 2 ) M_B ( 6 | 1 | 1 ) Now I want to move the plane A on the X-axis to the X coordinate ...
5k views

Why is Y up in many Games?

I learned at school that the z-axis is up. It is the same in modeling software like Blender. However in many games the y-axis is up. What is reason?
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Coordinates on the top left corner or center of the tile

I'm setting up a tile system where every tile has x and y coordinates. Right now I assume that the top left corner of the tile is positioned on it's coordinate on the screen, x = tileX * tileWidth and ...
5k views

Staggered Isometric Map: Calculate map coordinates for point on screen

I know there are already a lot of resources about this, but I haven't found one that matches my coordinate system and I'm having massive trouble adjusting any of those solutions to my needs. What I ...
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Curiosity on any Smartphones that Run on Android 2.3.3 with Different Screen Reoslution

I have a question regarding about any smartphones that run only in Android 2.3.3. Is the size of screen or the screen resolution is always HVGA or does it have capable of running this OS (Android 2.3....
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Coordinate spaces and transformation matrices

I'm trying to get an object from object space, into projected space using these intermediate matrices: The first matrix (I) is the one that transforms from object space into inertial space, but since ...
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XNA 3D coordinates seem off

I'm going through a book, and the example it gave me seems like is should work, but when I try and implement it, it falls short. My Camera class takes three vectors in to generate View and Projection ...
431 views

Precise Touch Screen Dragging Issue: Trouble Aligning with the Finger due to Different Screen Resolution

Please, I need your help. I'm trying to make a game that will drag-n-drop a sprite/image while my finger follows precisely with the image without being offset. When I'm trying on a 900x1280 (in X [900]...
1k views

Spherical to Cartesian Coordinates

Well I'm reading the Frank's Luna DirectX10 book and, while I'm trying to understand the first demo, I found something that's not very clear at least for me. In the updateScene method, when I press A, ...
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Orthographic unit translation mismatch on grid (e.g. 64 pixels translates incorrectly)

I am looking for some insight into a small problem with unit translations on a grid. Update and Solved I solved my own issue. See below for details. Everything in this part of the post turned out to ...
2k views

Convert rotation from Right handed System to left handed

I have Euler angles from a right handed system that I am trying to convert to a left handed system. All the information that I have read online says that to convert it simply multiply the axis and ...
2k 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 ...
644 views

Isometric Screen View to World View

I am having trouble working out the math to transform the screen coordinates to the Grid coordinates. The code below is how far I have got but it is totally wrong any help or resources to fix this ...
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Converting world space coordinate to screen space coordinate and getting incorrect range of values

I'm attempting to convert from world space coordinates to screen space coordinates. I have the following code to transform my object position Vector3 screenSpacePoint = Vector3.Transform(object....
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get coordinates of origin of coordinate system in second coordinate system by knowin matrices of one point in bith systems

Situation, two coordinate systems A, B. origins Oa, Ob. I have one point, for which i know modelview matrix (translatoin/orientation) in both systems. And what i need to get is modelview matrix of Ob ...
6k views

OpenGL ES and Screen Coordinates

Is there anyway I can make OpenGL ES 2.0 to accept coordinates (for Vextex for example) in int meaning the pixels instead of the default float system? Also how can I set the point (0,0) to be at the ...
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Draw a 3D object at specific coordinates on the screen

I'm creating an application which allows the user to manipulate 3D models. I would like to draw 3 axis representing the world coordinate system in 3D in order to give the user an idea where he is. ...
690 views

Convert point to its barymetric coordinates

I'm making a 2.5D game engine (in JavaScript) and I'm trying to get it to detect whether a block is under the cursor. This would be a simple task were it restricted to single-level isometric ...