A mathematical concept that can be used to express position, direction or velocity and which can simplify or outright trivialise spatial problems.

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17
votes
4answers
14k views

How can I calculate the angle and proper turn direction between two 2D vectors?

I am working on some movement AI where there are no obstacles and movement is restricted to the XY plane. I am calculating two vectors, v, the facing direction of ship 1, and w, the vector pointing ...
8
votes
7answers
2k views

What's the best way of transforming a 2D vector into the closest 8-way compass direction?

If you have a 2D vector expressed as x and y, what's a good way of transforming that into the closest compass direction? e.g. x:+1, y:+1 => NE x:0, y:+3 => N x:+10, y:-2 => E // ...
14
votes
5answers
5k views

Do I need the 'w' component in my Vector class?

Assume you're writing matrix code that handles rotation, translation etc for 3d space. Now the transformation matrices have to be 4x4 to fit the translation component in. However, you don't actually ...
4
votes
1answer
3k views

How do I find rotation in 3D based on a vector/normal?

I've been playing with Blender and Python, doing basic things like accessing vertices/normals,etc. I can get the normal of each face of a mesh. I was wondering, how can I get the rotation of a face ...
7
votes
2answers
5k views

How do I find the angle between two vectors?

I have 3 points on my screen: a = a point which is (c.x, 0) makes a line pointing straight up b = a user input touch, can be anywhere on the screen c = a moving object a _______.________ | ...
16
votes
1answer
4k views

Determine arc-length of a Catmull-Rom spline to move at a constant speed

I have a path that is defined by a concatenation of Catmull-Rom splines. I use the static method Vector2.CatmullRom in XNA that allows for interpolation between points with a value going from 0 to 1. ...
3
votes
4answers
4k views

How can I implement a directional melee attack?

I am attempting to make a top down game similar to the SNES Zelda games, in Unity 4.3, in 2D. When my character swings their sword, every enemy within a radius takes damage. I want to make sure that ...
8
votes
2answers
3k views

How to calculate the vector of an interception?

Given are a twodimensional space, and 1 friendly spaceship standing still, one foe is moving NOT directly to the friendly ship with known actual position, speed and direction. The friendly ship wants ...
8
votes
2answers
15k views

Moving a sprite in XNA/C#, using vectors

I'm currently looking into XNA game development with the C# language. I have two classes: the main game handler and a "sprite" class. Following is some basic pseudo-code which I hope adequately ...
3
votes
1answer
2k views

Make objects follow a strict path (Xna)

I am making a defence game. Naturally, this means that there needs to be objects following a path on the screen. I want to make it a strict path from one point to another to another. I could use an ...
5
votes
1answer
4k views

How do I rotate a sprite so that it is 'pointing' in the direction it is moving?

I have a sprite, e.g a missile, heading in a certain direction (using a velocity vector). How do I figure out its how much to rotate it so that it gets drawn 'pointing' in the direction it is ...
4
votes
2answers
1k views

Why isn't this physics code scaling velocities separately?

I'm working my way through this book and I'm trying to work this code out: var squaredVelocity = this.velocity.x*this.velocity.x + this.velocity.z*this.velocity.z; if ...
4
votes
2answers
422 views

What are the properties of “position, velocity, acceleration, rotation” collectively named?

They say naming things is one of the hardest problems in computer programming. They were right. Given the pseudocode below, what is a more appropriate name for this collection of properties? ...
3
votes
2answers
2k views

Bukkit shoot tnt & help with vectors

I want to shoot a piece of tnt from the players face and then let it explode when it hits the target block. if (cmd.getName().equalsIgnoreCase("cannon")) { ...
0
votes
1answer
78 views

Raycast Flashing problem

Can anyone tell me what is wrong with me code ? If you can see, whenever the player is in range of the raycast. The enemy turns red. But for some reason. Even when the player has meet the requirement ...
0
votes
0answers
106 views

3d game math problem [duplicate]

i'm very much new to 3d math operations. I know how to rotate 3d points certain degrees arbitrarily by any axis but we were given a strange problem to think on. I'll spare using actual numbers on ...
0
votes
1answer
534 views

Vector reflect problem

I'm testing some vector reflection and I want to check what happens when a ball collides with a paddle. So if I have: Vector2 velocity = new Vector2(-5, 2); position_ball += velocity; if ...
-2
votes
1answer
524 views

How does atan2 work when getting angle of a vector?

I know that atan2 gives me the absolute angle of any vector. But it doesn't give a value from 0 to 360 degrees. Instead, it gives a value (if I'm not mistaken), between 0 and 180, or between 0 and ...
25
votes
2answers
2k views

Calculating the rotational force of a 2D sprite

I am wondering if someone has an elegant way of calculating the following scenario. I have an object of (n) number of squares, random shapes, but we will pretend they are all rectangles. We are ...
17
votes
6answers
6k views

Vectors in game development

I'm new to programming and game programming. I've reading something about vectors and math, but I have a question - where do I use vectors in game programming? Maybe anyone can give a simple example ...
2
votes
1answer
281 views

Turning to face mouse

Given three points on the same Y plane; A ship A point along the ships heading A mouse cursor How can I find which direction and angle the mouse cursor is from the ships heading? I have a limited ...
2
votes
3answers
4k views

Get points on a line between two points

I'm making a simple space game in JavaScript, but now I've hit a wall regarding vectors. The game view is top-down on a 2d grid. When the user clicks on the grid, the space ship will fly to that ...
8
votes
1answer
602 views

Downprojecting an imaginary 4D mesh to the screen

As a mental exercise, I'm trying to imagine projecting an arbitrary 4D mesh onto the screen (2D). I'm guessing a single 4D triangle would still consist of only 3 points, however each of those 3 ...
6
votes
2answers
493 views

Vector problem: which one is the left / centre / right one?

In aviation, runways are named according to their magnetic orientation seen from the pilot's perspective. For example: a strip of asphalt oriented along the east-west axis will be named 9 for the ...
4
votes
2answers
3k views

Drawing a texture line between two vectors in XNA WP7

I want to create a simple graph maker in WP7. The goal is to draw a texture line between two vectors what the user defines with touch. I already made the rotation, and it is working, but not ...
1
vote
2answers
289 views

How can I project a vector on another vector?

I have a generic not normalized Vector3 v1 and I want to calculate its component along another Vector3 v2. I used to normalize the vector I want to be the direction and then multiplying the other ...
1
vote
2answers
727 views

What is the camera direction vector for an isometric view?

What values correspond to a 3D vector for screen-normal from within an isometric game? It needs to be in game coordinates. It is a standard isometric where tiles are rotated 45 degrees and half ...
1
vote
1answer
952 views

Rotate triangle so that its tip points in the direction of the point on the screen that we last touched

OpenGL ES - Android. Hello all, I am unable to rotate the triangle accordingly in such a way that its tip always points to my finger. What i did : Constructed a triangle in by GL.GL_TRIANGLES. Added ...
1
vote
1answer
519 views

Transform 3d viewport vector to 2d vector

I am playing around with 3d transformations and came along an issue. I have a 3d vector already within the viewport and need to transform it to a 2d vector. (let's say my screen is 10x10) Does that ...
7
votes
1answer
3k views

How do I calculate collision response between a sphere and a plane?

I'm trying to create a simple 3D game and need to constrain the player within the limits of the game world. When the player hits the sides of the world I want the player's ship to bounce off slightly. ...
6
votes
1answer
2k views

Rotate object to face player

This is probably a simple vector question, but I'm not sure how to do it. I have an object at vector position (ox,oy). Potentially every update, the user walks around the screen, and will be at ...
4
votes
3answers
1k views

Tetris - Rotations using Linear Algebra (Rotation Matrices)

I'm making Tetris in Java and am at the point of rotations... Originally I was hardcoding each rotation: if (direction.equals("right")) { if (shape.equals("Bar")) { if ...
4
votes
2answers
290 views

Getting an angle in degrees from north

This may have been asked already, but I was unable to find it, because I don't really know what I'm looking for. I drew a picture: I need theta. I've seen various solutions using Vector.Dot, and ...
3
votes
3answers
2k views

Getting correct angles between Vector3s

I'm working on a project where you can draw lines between points. You select one point and drag the mouse onto another point and a line is drawn between them. The line itself is a 3d object which is ...
3
votes
2answers
96 views

Need the co-ordinates of innerPolygon

Let say I have this diagram, Given that i have all the co-ordinates of outer polygon and the distance between inner and outer polygon is d is also given. How to calculate the inner polygon ...
3
votes
3answers
3k views

Vector images (SVG or other formats) support in libgdx or other Android framework? [closed]

I'm looking for a website to create games for Android. I'm interested in something that supports vector images. Do you know if libgdx supports them or is there a convenient way to use them in libgdx? ...
2
votes
4answers
2k views

How to find the entity I'm looking at?

I am currently making a mod for Minecraft but I have come to a stop because I am lacking in some knowledge. I need to get data for the entity I am looking at, which I believe requires the use vectors, ...
2
votes
2answers
859 views

How to calculate vector that is perpendicular to the direction of moving in Flash?

In flash i have a class that extends movieclip and i am moving it forward, up and down, and rotating it. How can i calculate the vector that is perpendicular to this movieclip?
2
votes
2answers
432 views

Swapping axis labels between 2D and 3D coordinates

My game world is 3D. The map is only 2D, however. It is natural to think of the map as having an X and Y axis. And it is natural to think of the world has having an X, Y and Z axis, where Y is ...
1
vote
1answer
115 views

Eculidean space and vector magnitude

Below we have distances from the origin calculated in two different ways, giving the Euclidean distance, the Manhattan distance and the Chebyshev distance. Euclidean distance is what we use to ...
1
vote
2answers
179 views

matrix to rotate a vector to a known arbitrary axis

Let's say I have a vector V (v.x,v.y,v.z) which is normalized and points somewhere in 3d space. And that I have another vector Z of (0,0,1). Knowing only these two things I'm looking for a ...
1
vote
2answers
257 views

Adding an angle variance to a 3d vector

I am converting a particle emitter from 2d to 3d. In the 2d system the original coder used a random angle variance and added it to the angle. So it would be something like: thisAngle = emitterAngle ...
1
vote
1answer
123 views

3D vector graphics - maintaining correct Z 'length'

So I'm trying to build myself a 3D display 'engine', or whatever it ought to be called. I've been experimenting with PyGame, as it's familiar to me. In a way this has almost been more an excuse to ...
1
vote
3answers
1k views

How to move an object along a vector

Let's say I got an object A and object B in a 2D game. I create a vector leading from A to B. It's name is AB. How can I make A move along the vector AB and reach B? One way I was thinking of doing ...
1
vote
1answer
2k views

Basic Car Movement, Converting 2D Vectors to 3D problems

I'm trying to follow this guys method for steering a basic car. Link. It's the first example I can sort of get my head around and I'm trying to convert it to a working 3D version. To get some scope, ...
1
vote
1answer
419 views

How do I get the axes for SAT collision detection

In SAT collision detection how do I calculate the axes for projection?
0
votes
0answers
41 views

How to find optimal perpendicular axis of rotation vector to draw arrows?

I am drawing lines on the screen. Each line has a point (x,y,z) and a direction (u,v,w). I want to draw arrow heads on these lines, like two lines that start from (x,y,z) and leave at a 15 degree ...
0
votes
2answers
254 views

Finding vectors with two points

We're are trying to get the direction of a projectile but we can't find out how For example: [1,1] will go SE [1,-1] will go NE [-1,-1] will go NW and [-1,1] will go SW we need an equation of ...
0
votes
1answer
94 views

Rotating sprites

I'm a beginner at making games, i'm currently only working in 2D using XNA. So far all of my games i've been using the following logic for sprite movement: if(left key pressed) sprite_x_position ...
0
votes
2answers
1k views

Calculating angle between two vectors to steer towards a target

I have been trying to implement a path following steering behaviour for AI in a 2D racing game. I have two vectors: futurePosition represents the predicted future position given the car's current ...