Mathematics questions deal with the arithmetic, geometry, calculus, formulae and other calculations used in the development of a game.

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11 views

Mixing interpolation with extrapolation in multiplayer game

I am creating a multiplayer drag racing game and have difficulties mixing extrapolation and interpolation. To save network bandwidth i am getting information from the opponent only on his button ...
2
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1answer
49 views

Camera roll has no effect

Consider my following (abstracted) C# w/ SharpDX code: class Game { Camera _camera = new Camera(); private void Window_KeyDown(object sender, KeyEventArgs e) { // Roll if ...
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0answers
14 views

How to calculate positions and randoms in scene. SpriteKit

So here is a code : static inline CGFloat randomInRange(CGFloat low, CGFloat high) { CGFloat value = arc4random_uniform(UINT32_MAX) / (CGFloat)UINT32_MAX; return value * (high - low) +low; } ...
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2answers
31 views

How to find the total bounds rectangle around a list of rectagles

Rectangle object: a simple data structure of 4 floats (w,h,x,y). I have an array of 2 or more rectangles and want to create a rectangle that surrounds all of them: The result rectangle, calculated ...
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2answers
75 views

Find closest point from an origin, in a mesh

I want to do something similar to a raycast. With a raycast, you can set an origin and a destiny, and check where the ray collides with something but only with a line. What I want to do, is given an ...
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1answer
63 views

Calculating ball trajectory in Pong

I'm making a Pong game and I'm just looking for a simple way to calculate a straight travelling path for the ball based on the angle of the ball. How would I go about implementing something like this? ...
0
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1answer
77 views

Projecting a light onto a quad

I need to project the light onto the quad and use its value for translating the vertices. I'm currently having 6 vertices, two quads, The points are A X C B Y D Point X, Y are coming from two ...
1
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2answers
93 views

How can I get a direction vector from a an Euler angle?

Im trying to get a directional vector from an euler angle. But im not getting how to do it. This is what i got so far. escapeAngle += 90; var radians = escapeAngle * (Mathf.PI / ...
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1answer
43 views

Why isn't the bitangent calculated?

In teh tangent space vertex attributes why is the bitangent (aka binormal) provided as an attribute instead of calculated? If the three vectors of the tangent space must be perpendicular then the ...
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0answers
38 views

3D model editor manipulators

I'm trying to make my own 3D model editor to better learn 3D programming. I have my translate manipulators and I'm trying to calculate the Vector2 that the mouse would have to move in order to move an ...
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0answers
51 views

Script to intelligently move aircraft using curves [Unity]

I am trying to code a script to move an aircraft entity from point A to point B and at some point in the middle of moving have the aircraft forward vector face Point C (to fire a missile at an enemy ...
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1answer
83 views

Moving turret aiming at moving target

I've found this post Turret Aiming Formula on Reddit and a nice answer a while back. The solution in the answer works great for still sanding turrets but is almost unusable for moving turrets since ...
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1answer
46 views

How to find the right direction to plug a sword into a rig's hand after projecting it?

I've downloaded BVH animations and projected it following a book. I can now see a 3D moving rig and it looks alright. The problem is, now I want to plug a sword on the hand of the rig, but I don't ...
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1answer
38 views

What is the actual formula to find the vertices of an animation frame in using a BVH file?

I've read this tutorial and tried many formulas to build the skeleton. I am able to build it without the rotations, but those break everything. This, for example, is a simplified code for one of my ...
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0answers
23 views

Cone Lighting formula for 2D projection space?

There is a good formula for a 3d cone lighting: float angleCos = dot(lightVector.rgb, lightDirection.rgb); attenuation = saturate((angleCos-coneCos)*coneCos); What if I want to compute whether my ...
2
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1answer
128 views

3D Camera Rotation

Please, forgive me, but I need help and I've been stuck on this for a few weeks now, I'm making no progress and everywhere I go and I see a different answer, everything I try doesn't work. I've had ...
8
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1answer
467 views

How can I project a 3D point onto a 3D line?

Let's say I have a line defined by two points, A and B, both in the form (x, y, z). These points represent a line in 3D space. I also have a point P, defined in the same format, that isn't on the ...
2
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1answer
114 views

What is Vector Projection and what is it's use in games?

Couldn't find a clear enough answer on Google. I know what vectors are. But what does it mean to project a vector onto another, and what is it used for in games?
2
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1answer
112 views

C# - Separating Overlapping Rectangles

I'm trying to separate an arbitrary number of randomly sized rectangles, while still keeping them snapped to the grid, and somewhat packed together nicely. The goal is to start with something like ...
1
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1answer
61 views

The correct way to transform a ray with a matrix?

Playing with XNA Triangle Picking Sample I found out that it does not work well if you scale the world matrix of the objects you want to pick. When I dug into the implementation I found this comment ...
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0answers
6 views

Using morton codes to compress data - how? [migrated]

I've been reading something about morton codes and I got that locality is preserved in the sequence of generated numbers. What I don't understand is how this information can be used to compress data ...
11
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3answers
411 views

How do I lerp between values that loop (such as hue or rotation)?

View Demo I'm trying to make the joint rotate smoothly around the center of the canvas, toward the angle of mouse pointer. What I have works, but I want it to animate the shortest distance possible ...
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2answers
30 views

Compute cone angle (cos) given side and hypotenuse vectors at time 0 and world matrix at time 1

I need a formula for the cosine of a cone, given normalized side vector, normalized hypotenuse vector at time 0 and world matrix at time 1. This is needed to implement custom spotlights in a level ...
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0answers
32 views

libgdx get rotated sprite coords points

I would like to get the position of each edge of a sprite when he has been rotated. I have no idea how to do it, I made a image to explain it. I would like to get the X and Y position of each Red ...
3
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1answer
55 views

Field of view determination with partially opaque cells

I'm currently implementing the field of view of a player in a 2D-grid based game. I've chosen a standard ray tracing algorithm because he really fits the features needed in my game. However, the ...
3
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2answers
99 views

How simulate the return effect of the wheel of fortune needle

I am trying to create a spinning wheel which slows down after a specific time. I managed to simulate the slowdown of the wheel but I need also to put a needle which go up and down with an angle of ...
3
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1answer
72 views

What is an axis aligned integer bounding box?

In this paper, in the Distance field computation section, it says that an axis aligned integer bounding box of a Prism has to be calculated. Can someone explain what an axis aligned integer bounding ...
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0answers
45 views

Calculating intersection of line segment with view frustum

I want to calculate the intersection of a line segment with the view frustum. Here's what I tried so far. The code works perfectly when the look direction vector is orthogonal to the line. E.g. ...
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0answers
34 views

HTML5 Canvas: Get rect coords after rotation (relative to screen)

update: function(delta) { for (var i = 0; i < this.bullets.length; i++) { this.bullets[i].velocity = this.bullets[i].speed * delta; this.bullets[i].contextX += ...
3
votes
1answer
98 views

Converting between Spiral Honeycomb Mosaic and axial hex coordinates

There seems to be quite a lot of logic in dealing with hexagonal grids using a system of axial coordinates like the one described here. In doing some reading about hex grids, though, I ran across the ...
0
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1answer
35 views

Rotating image around a given point

Im trying to simulate shadows in a 2d RPG, So far I can make the shadows but i cant blit them properly, Im trying to rotate them according to where the "sun" is (just a position) I have looked at ...
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0answers
46 views

how to do picking in 2d lwjgl

I searched the whole internet, but I couldn't find something useful. How to do picking (like ray picking) in lwjgl in orthographic mode (2d)? I think this is less confusing than picking in 3d, but I ...
4
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1answer
356 views

Algorithm for randomly generating reachable platforms

I want to randomly generate reachable platforms on the fly for a 2D game. Right now, I am just creating platforms at random x,y positions. Only 4 platforms can exist at once, so once the 5th one is ...
0
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1answer
46 views

Getting the position of a directional light w.r.t. a moving object.

I have a forward vector of my object, which is a bike, and its position, and I have a directional light direction. I would like to know where the light is with regards to the bike ...
1
vote
1answer
87 views

Calculating How To Intercept a Moving Object [duplicate]

So I have two objects, Target and Interceptor. Target's position, direction of movement and movement speed are known, and Interceptor's position and movement speed are also known. Both movement speeds ...
8
votes
4answers
354 views

Modify random distribution functions :: Make it less likely to get multiple similar values in a sequence

I want to generate a sequence of numbers for procedurally generating planets in a galaxy sector. Each planet should be placed randomly, however it should be very unlikely that two planets are directly ...
0
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1answer
34 views

Best method for selecting points from a point set - path distance

having a big set of points and a polygonal path what is the best way to select a set of points that are at a certain distance or smaller from the path? Or do I need to iterate thru all points on each ...
1
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2answers
83 views

How can I fix my sprite being rotated 90 degrees more than toward the mouse?

I am trying to get a Sprite in LibGDX to look at the player's mouse. Here's the code I have (mind you, I am using JRuby): target = mouse_position.sub(spatial.position) rotation = ...
1
vote
1answer
81 views

How can make an object orbit a sphere in a random direction?

How can I move an object on a random orbital path around a sphere? I've created some objects at an initial position that is essentially a random point on the sphere offset by some distance (say, ...
0
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0answers
43 views

Java Angle Math: Calculate how near the player looks to an entity [duplicate]

I am programming a Minecraft Bukkit plugin and need a way to calculate an input number from 0 to 360 for displaying a custom compass / radar. So if the player directly looks at the object (shouldn't ...
1
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2answers
80 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 ...
6
votes
1answer
178 views

Square Grid Polygonal Terrain Query algorithm?

I have a square, fixed-grid terrain with one terrain type per grid unit in my game, and I want to do an arbitrary polygonal terrain query which returns all of the grid units enclosed/intersected by ...
0
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0answers
90 views

Alter a model-view-projection matrix

I have a model-view-projection matrix created based upon my camera. Is it possible to make alterations to it after it was computed to affect the corners of the resulting camera frustrum? For example, ...
0
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1answer
93 views

What are the correct angles in the Top-down perspective?

In the following picture it says that in the Top-down perspective the angles are 90°, but if it would be 90° then you shouldn't see the front of the building and the roof at the same time... So what ...
6
votes
2answers
143 views

How do I avoid interpolation artefacts when scaling up a heightmap?

I am using a bicubic interpolation algorithm in order to upscale a height map, and I am noticing some artifacts around the pixels boundaries. However, these artifacts don't seem to appear when I use a ...
0
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1answer
70 views

Trying to make sprite float up and down [closed]

Using LibGDX + Box2D and my understanding of the answer posted from this question: Here I apply the following impulse: // modify sprite's Box2d Body object int a = 8; // amplitude int f = 1; // ...
-1
votes
1answer
56 views

lerp z rotation towards mousepointer

I am trying to get transform.rotation.z to chase the mouse pointer at a rotation speed. But I get a very weird results and can't figure out what I am doing wrong. var mp = Input.mousePosition; ...
-2
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1answer
79 views

Lerp speed or lerp time [closed]

Am I right about the fact that lerping can be done over a set period of time or at a speed which will continue until the target is reached? How are the formulas for the two? Is it something like ...
0
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0answers
55 views

How to convert bones skeleton into joints skeleton?

I'm exploring skeletal animation and taking Half-Life SMD format as example. It has skeleton rigged as hierarchy of joints. Each joint has a parent and offset + rotation to it. Now I'm importing ...
8
votes
3answers
448 views

Can I jump from A to B?

I'm making some rudimentary AI for my side-scroller and I need to know whether an AI unit can reach point B from point A simply by taking a jump. Flight trajectory of my characters is a bit unusal as ...