# 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.

214 views

### Inventory Grid Detection

I'm working on creating an inventory system for a game. The inventory system will use cells and 2D images to represent items, like Minecraft, Diablo, or WoW. I've hit a bit of a snag when trying to ...
213 views

### Directional light and matrix issues

I'm trying to implement basic directional lightning in OpenGL 3.3 by emulating the logic shown in this guide: http://www.arcsynthesis.org/gltut/Illumination/Tutorial%2009.html I do not understand ...
118 views

### A controlled trapezoid transformation with perspective projecton

I'm trying to implement a controlled trapezoid transformation in Adobe Flash's ActionScript using the built-in perspective projection facility. To give you an idea of how the effect looks like: ...
106 views

### What effect does the amount of 0 in a stat have. [closed]

Basically I want to know if the following three characters are the same character A health 10 strength 3 defence 2 character B health 100 strength 30 defence 20 character C health 1000 ...
676 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 ...
456 views

### deferred rendering and point light radius

I use a common attenuation equation for point lights: attenuation = 1 / kc + kl * d + kq * d^2. I use deferred rendering so I need to know a light radius. An example light has following intensity: ...
192 views

### games logic based on closed shapes

I would like to know the math concepts behind shape based games like http://www.miniclip.com/games/fat-slice/en/ To be specific, I would like to know on how to model shapes programmatically finding ...
122 views

### How to predict encounters between a ship and a body's sphere of influence in 2D

Long time listener, first time caller. I'm making a little hobby game in XNA, its about transport ships in space, analogous to container ships at sea. There are to be AI ships and player controlled ...
2k views

### How to extract euler angles from transformation matrix?

I have a simple realisation of entity/component game engine. Transform component have methods to set local position, local rotation, global position and global rotation. If transform is being set new ...
166 views

### Accumulating rotations for camera

It seems there are three ways to store a camera's rotation: in angles, view matrix or quaternion. I was using euler angles since when I used a matrix it had a tendency to accumulate rounding errors ...
274 views

### How to build a math module and simulate a system?

For example, in the classical game SimCity: an economic model to simulate the supply and demand of the city, then calculate how many people live in each building, how many people work there. a ...
564 views

### LibGDX Perspective Camera for 2D

I'm very new to LibGDX and I'm 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 ...
245 views

### How to implement armor? [closed]

I am a newbie in Python, I am very bad at math too and I need some help. Also close/move this post if you feel this isn't the right place for it. Hero1 = 5000 # His HP is 5k. Hero1dmg = 200 # ...
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### How to change Vectors due to change in it's dependent Base Vector?

PLOT : I have been developing a game where the player falls down on Y axis and the camera is a Top-Down view camera. The camera, player (main character in the game) movements etc. have all been ...
598 views

### 2D car physics and high speed turning

I've been looking at the following page, which has been very helpful: http://www.asawicki.info/Mirror/Car%20Physics%20for%20Games/Car%20Physics%20for%20Games.html but have come into problems with the ...
70 views

### Matrix Translation Transformation Question

I've been reading a lot about computer graphics lately and because of it I'm building my own math library's for fun. I was reading about Matrix Translation and Homogeneous Coords, and was wondering ...
359 views

### Defining an OpenGL unit

I have read that you can define your OpenGL unit by using glViewport. As far as I understood if you use something like glViewport(0,0,600,600) then 1 OpenGL unit = 600 pixels. Now my problem is what ...
206 views

### Why does matrix multiplication lead to different result if it's done on CPU, compared to GPU(shader)?

If I'm calculating a "camera space" on the CPU, by multiplying the view with the projection matrix on the CPU , and afterwards multiplying the world to the result my vertices do not pass to the pixel ...
220 views

### Get intersected volume of two planes in 3D

I'm working on AABB - AABB collision response and I'm having trouble figuring one part out. My situation is as follows (see image). I have a player AABB (blue) and an object which collides (brown). ...
328 views

### How can I change the acceleration of an object to arrive at a particular time?

I'm trying to write some code to change an acceleration factor so a ball will arrive at a destination in a desired time. The problem is I don't know time (t) but I do know I want it to arrive at (t - ...
108 views

### Movement constrained to the faces of a cube

The basic setup I'm working with is a cube rendered in-Engine (Panda3d, although I only am looking for a generalized solution) as well as a 2d square on one face of the cube. The eventual outcome I'm ...
349 views

Short version: What can happen to the output of a vertex shader that leads to no(or very few) pixels being drawn, especially in relation to a perspective matrix. Long version: My problem refers to ...
226 views

### A* for non grid network

For my specific case, I am trying to find a path finding implementation similar to what described here. I could see reference implementation for A* and HPA*, but I wonder how to extend A* to simple ...
307 views

### Creating a frustum for culling in world-space glm matrices

I need to do frustum culling where the bounding boxes are in world-space to determine which entities get to be updated/drawn. I was trying to use the classic projection/view matrix plane extraction ...
997 views

### how to rotate enemy to face player? [duplicate]

Okay so i havebeen rotating my enemy to face the player using float targetrotation = Math.Atan2(playerpos-enemypos); enemy.rotation = targetrotation; (<this line of code i want to change) This ...
181 views

### Jump function of player [duplicate]

I'm developing game in marmalade sdk in c++. I have player in the area.and I wanna make him jump when i pressed a button.When I use this player.moveUp(5px); it just go up 5px, but he has to fall down ...
165 views

### How to calculate size of object depending of its height on the screen?

I am programming a mostly 2D game on Android (with Andengine), but the player is a bouncing ball (kinda in 3D). I wanted to make the bouncing of the ball the most realistic possible, using quadrilic ...
66 views

### Build a Cube/Prism from other varied Cubes/Prisms [closed]

I'm wondering, are there any algorithms or theories in existence (that aren't patented/proprietary/protected) that would take a series of 3d rectangular prisms (or cubes but a cube is a prism) and ...
187 views

### Plotting entities on a radar

I'm trying to build a radar system like the one in the original X-Wing games. The way it works is that there are two circular radar systems, one for behind the ship, and one for infront. So, I've ...
2k views

### Converting a 2D curve into points for data storage

I’ve created an algorithm which converts any curve i.e. path into minimum number of points so that I can save it into a file or database. The method is simple: it moves three points in equal steps ...
706 views

### 3D isometric depth sorting

How is it possible to depth sort tiles and objects in an isometric environments without any limitations? I've been researching this for a while now and there seems to be no publicly available answers ...
216 views

### AABB of a sphere's screen space projection

What is a nice, neat way to get the AABB of a sphere's projection onto the screen? This is to determine simplified geometry for lights in deferred shading.
166 views

### Distribute circles evenly on Screen - circle packing

I want to evenly distribute a random amount of circles with random diameter on the screen for. This level doesn't scroll so the users screen resolution sets the limits. Further I would like the ...
600 views

### Bezier curve not drawn correctly

I'm trying to draw a bezier curve using 3 points. If I use the quadratic form: I get this result: And I believe it's correct. Now since I need to draw it with a variable number of points, ...
135 views

### Physics movement prediction is way off [closed]

I'm making a simple, non-networked game. There are two players and a ball. In implementing the AI for the second player, I've run into a huge problem predicting where the ball will hit the ground. ...
233 views

### A formula for point calculation based on value A's proximity to value B

I am trying to find a formula to use for my rhythm game's scoring. Basically there is a Guide entity and a Live entity. You control the Live entity and have to match it as closely as possible to a ...
746 views

### How can you extract orientation from a transformation matrix?

I have a 4x4 transformation matrix M, and I want to find out the shape of a sphere when transformed by M. (Sphere is at the origin and has radius 1.) I know I can find the center by just multiplying ...
121 views

### Increase restitution (bounciness) of an object in a JavaScript formula

I'm going slightly around the houses on this one. I originally started a thread over on Stack Overflow about it but then it seemed to diverge into mathematics, with no joy from the SO community over ...
343 views

### How do I calculate consistent frame timings at 60fps?

I'm writing an HTML canvas game that uses requestAnimationFrame and therefore runs at 60fps, although this is more of a question about failing arithmetic than about JavaScript. If I measure the time ...
387 views

### How to rotate a direction

I'm working a spotlight for my deferred renderer and I'm having trouble with matching the mesh to the visual representation of the light. Right now my mesh is a cone, the apex of the cone is at ...
274 views

### How do I detect the intersection of a curve with itself?

I'm developing a game in which the player can draw a line. I want to detect if that line intersects with itself. How would I do this?
293 views

### Any book about math in game design? [closed]

Game designers need math as one of their tools for designing game, unfortunately I can't find one book concentrate on this topic. I know there's math book about game programmer, but designer need ...
152 views

### In a regular grid, how can I tell which tile a position is in?

I have a position on the screen, how do I calculate which grid tile that position is inside? I know the number of tiles in the grid, and the size of the screen (including how many tiles fit on it ...
214 views

### How does a point squared equal the radius squared?

I am working on a simple ray tracer but I don't understand some of the formulas. One that is bugging me at the moment is this: If a sphere is centred at origin, a point p lies on a sphere of ...
239 views

### 2D field of view detection inverted

I'm not sure if the title matches what I'm actually facing I'm trying to test if I can see a point is in my field of view (in the context of an NPC seeing in it's direction.) I know that: cos0 = ...
475 views

Possible Duplicate: How to convert mouse coordinates to isometric indexes? Okay, I apologise in advance if I make no sense here. Basically, I've got a simple application that takes in a ...
259 views

### How to do perspective projection “parallax” but without changing the scale or offset of objects?

Hello everyone I have this problem that I have tried everything I could think of. The problem: I am making a 2D game with parallax effect but I am using 3d space so am not simulating the parallax but ...
428 views

### Derive a algorithm to match best position

I have pieces in my game which have stats and cost assigned to them and they can only be placed at a certain location. Lets say I have 50 pieces. e.g. Piece1 = 100 stats, 10 cost, Position A. Piece2 ...