# Tagged Questions

Arithmetic, geometry, calculus, and all else which resolves the number-crunching necessary in a game. Math questions are those that deal with the formulae and calculations used by the game in various parts.

113 views

### Find the footprint of an isometric entity

I'm working on making a 2D isometric engine in Java. I'm getting into collision detection and I've hit a bit of a problem. Characters in-game are not restricted to movement from tile to tile - they ...
68 views

### Retrieve outer most points on a 2d graph

G'day everyone, I have a 2d graph which has some points plotted on it. What I need to do is get only the outer most points so that I can connect them up (isn't really relevant). What I can't seem ...
464 views

### Catmull Rom Spline - Constant Speed

Given the equations found in the answer here: Determine arc-length of a Catmull-Rom spline How would one A) Apply this to a 3D Catmull-Rom Spline, and B) write A out programmatically (for the math ...
310 views

### Orbiting multiple objects evenly around a changing radius

I have multiple objects (circles) and I want to place them in a circle, with even distance between each one, and have them orbit the center of the screen. If I remove one object, I want the orbit ...
583 views

### 360+ degree rotation skips back to 0 degrees when using Math.Atan2(y, x)

I'm new to XNA and this is my first actual project, so forgive my noobness. I'm using jointAngle = System.Math.Atan2(RightStick.Y, RightStick.X); in order to set an angle of a joint (farseer) so ...
289 views

### Min/Max of two vectors?

This seems like a simple question, but i'm having trouble searching the internet for it. In XNA, during a collision detecting method, I would determin the minimum of some vectors. // Get the minimum ...
163 views

### getting direction of x and y… north,south,east,west

I have a player in the center of the screen, where I also have my mouse position origin. (0,0) I would like to know the direction of the mouse, imagine splitting the screen with a X, so the top ...
106 views

### What OpenCL video cards (or FPGAs) features are needed for high speed multiplication?

I'm benchmarking some cryptographic related software and am looking for video cards that are better at parallel multiplication vs parallel addition. Is there any prior work that would graph video ...
966 views

### Understanding math used to determine if vector is clockwise / counterclockwise from your vector

I'm reading Programming Game AI by Example by Mat Buckland. In the Math & Physics primer chapter there's a listing of the declaration of a class used to represent 2D vectors. This class contains ...
1k views

### Scale a normalized 2D vector always to the same length

For any normalized 2D vector, except for ( 0, 0 ), how would I scale the vector to always be the same length? For example: int length = 10; vector v = vector( 0.1, 0.5 ); vector v2 = vector( 0.3, ...
513 views

### Isometric - precise screen coordinates to isometric

I'm trying to translate mouse coords to precise isometric coords (I can already find the tile the mouse is over, but I want it to be more precise). I've tried several different methods but I seem to ...
450 views

### convert orientation vec3 to a rotation matrix

I've got a normalized vec3 that represents an orientation. Each frame of animation, an object's orientation changes slightly, so I add a delta vector to the orientation vector and then normalize to ...
264 views

### Diamond shaped selection on a staggered iso map

I have a staggered isometric tile map and want to do a selection that aligns with the diamond shape of the tiles. This is what I mean: So I got two points on screen and their map cell coordinates. ...
227 views

### Vector vs Scalar velocity?

I am revamping an engine I have been working on and off on for the last few weeks to use a directional vector to dictate direction; this way I can dictate the displacement based on a direction. ...
347 views

### 2D Smooth Turning in a Tile-Based Game

I am working on a 2D top-view grid-based game. A ball that rolls on the grid made up of different tiles. The tiles interact with the ball in a variety of ways. I am having difficulty cleanly ...
173 views

### How do I draw a dotted or dashed line?

I'm trying to draw a dashed or dotted line by placing individual segments(dashes) along a path and then separating them. The only algorithm I could come up with for this gave me a dash length that was ...
2k 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 ...
108 views

### Getting to math applications gradually

I'm currently getting a formal degree related to computation, in particular my current focus is numerical programming, scientific computing and machine learning. I'd love to apply that knowledge in ...
177 views

### Y Axis inverted on vertex output

I've got my project running and somehow it seems my vertex y components are inverted. 10 in the positive on Y goes down and 10 negative on the Y axis goes up. I can't find anything with the ...
116 views

### Typical Applications of Linear System Solver in Game Developemnt

I am going to write a custom solver for linear system. I would like to survey the typical problems involved the linear system solving in games. So that I can custom optimization on these problems ...
316 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... ...
631 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, ...
1k views

### Line Intersection from parametric equation

I'm sure this question has been asked before. However, I'm trying to connect the dots by translating an equation on paper into an actual function. I thought It would be interesting to ask here instead ...
169 views

### Build a view frustum from angles

I have 4 angles, left, right, top & bottom. These angles are in degrees. They define the angle between the forward vector and the corresponding side. I am trying to use these to calculate the ...
170 views

### Rotate/Translate object in local space

I am just trying to create a movementcontroller class for game entities. These class should transform the entity affected by the mouse and keyboard input. I am able to calculate the changed rotation ...
349 views

### 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 ...
192 views

### Move projectile in direction the gun is facing [duplicate]

Possible Duplicate: Move sprite in the direction it is facing? I am attempting to have a projectile follow the direction a gun is facing. When using the following code I am unable to make ...
157 views

### How to transform mesh components?

I am attempting to transform the components of a mesh directly using a 4x4 matrix. This is working for the vertex positions, but it is not working for the normals (and probably not the tangents ...
152 views

### Using NumPy arrays as 2D mathematical vectors?

Right now I'm using lists as position, velocity, and acceleration vectors in my game. Is that a better option than using NumPy's arrays (not the standard library's) as vectors (with float data ...
584 views

### Do I need a Point and a Vector object? Or just using a Vector object to represent a Point is ok?

Structuring the components of an engine that I am developing along with a friend (learning purposes), I came to this doubt. Initially we had a Point constructor, like the following: var Point = ...
822 views

### Re-create 2D side-on wave effect from Worms game

I'm trying to recreate the waves/water effect from Worms ( see here http://youtu.be/S6lrRqst9Z4?t=31s ) From what I understand its not actually a sprite, its procedurally generated by something like a ...
277 views

### Point inside Oriented Bounding Box?

I have an OBB2D class based on SAT. This is my point in OBB method: public boolean pointInside(float x, float y) { float newy = (float) (Math.sin(angle) * (y - center.y) + Math.cos(angle) * ...
120 views

### Logarithmic spacing of FFT subbands

I'm trying to do the examples within the GameDev.net Beat Detection article ( http://archive.gamedev.net/archive/reference/programming/features/beatdetection/index.html ) I have no issue with ...
456 views

### Determining if something is on the right or left side of an object?

I have a character in a 3D world which is facing an arbitrary direction on a flat plane, the player can click on the left or right side of the character and based on which side is clicked on a ...
374 views

### Understanding normal maps on terrain

I'm having trouble understanding some of the math behind normal map textures even though I've got it to work using borrowed code, I want to understand it. I have a terrain based on a heightmap. I'm ...
291 views

### Tilting towards turn direction (for a motorbike)

I have a motorbike which moves along based on a direction vector, I set its forward direction to the direction it's moving. What I'd like to also do with it is have the motorcycle tilt in the ...
174 views

### Camera lookAt target changes when rotating parent node

have the following issue.I have a camera with lookAt method which works fine.I have a parent node to which I parent the camera.If I rotate the parent node while keeping the camera lookAt the target , ...
936 views

### Eight or infinity sign trajectory

When I want to move object around point I do: point.x *= cosf(timer.timeElapsed); point.y *= sinf(timer.timeElapsed); How to make point move on eight or infinity sign trajectory?
209 views

### What kind of math should I be expecting in advanced programming? [duplicate]

Possible Duplicate: What math should all game programmers know? And I don't mean just space shooters and such, because in non-3D environments it's obvious that not much beyond elementary ...
215 views

### Normalizing the direction to check if able to move

i have a a room with 4 walls along the x and z axis respectively. My player who is in first person (therefore the camera) should have collision detection with these walls. I'm relatively new to this ...
169 views

### Portal View/Projection Matrix near plane

For RenderToTexture/Camera based portal rendering, the basics seems simple enough. However, with a free camera, most of the time it is going to be looking at such portals at an angle: Now a ...
134 views

### Characteristics, what's the inverse of (x*(x+1))/2? [closed]

In my game you can spend points to upgrade characteristics. Each characteristic has a formula like: A) out = in : for one point spent, one pont gained (you spend 1 point on Force so your force goes ...
1k views

### How to determine which thrusters to turn on to rotate the ship?

The configuration of the ship changes dynamically, so I have to determine which thruster to turn on when I want to rotate the ship clockwise or counter clockwise. The thrusters are always axis aligned ...
120 views

### setting the position in different resolution

I have a normal game window which is 640*480, and everything is fine, but when I try to maximize the window, the objects translate to different positions on the screen, for example If I have a circle ...
79 views

### Vector transform equation explanation

I'm trying to understand the maths of moving points in a 3d space by making a game written in C#. I'm looking at this wolfire blog series which explains some basic 3d maths. I've read the first two ...
112 views

### How do I apply a force using the object direction and speed?

I have a 3D object moving and I need to be able to apply forces to it such as gravity. In 2D, I would simply store its movement in dx and dy, but since this is in 3D, I am using a Vector3D direction ...
104 views

### Initial direction of intersection between two moving vehicles? [duplicate]

Possible Duplicate: Predicting enemy position in order to have an object lead its target I'm working with a bit of projectile prediction for my AI and I'm looking for some ideas, any input? ...
322 views

### Confusion about Rotation matrices from Euler Angles

I am trying to learn more about Euler Angles so as to help myself in understanding how I can control my camera better in the game. I came across the following formula that converts Euler Angles to ...