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.

148 views

Is there a memory read/write or performance difference when applying affine transformations on a movieclip rather basic elementary math

I am using Actionscript 3.0 to make games and I fall into the category of programmers who use ball.x+=5; ball.y+=5; in order to move a ball by 5 pixels horizontally and vertically. Well, now i seem ...
962 views

top down game - checking, drawing enemy's line of sight area with obstacles

Examples of what i'm going to need: I'm using cocos2d to draw a CCTMXTiledMap, on those tiles i'll have to draw the LOS cone. How would i test if the player is within that cone, taking obstacles ...
273 views

rotating an object from sourceAngle to destAngle, both 0-359, clockwise or counter clockwise?

I've got a game object i need to rotate. It's current angle is player.rotation, the destination is targetAngle, both in degress, 0 to 359. I've got a function named rotateDirection(float sourceAngle, ...
120 views

Need a better function for transportation efficiency

I'm making an economic kind of game, and one of the things I'm simulating is the transportation of resources to a central depository, e.g. moving metal from a mine to the city (so it can be turned ...
954 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 ...
225 views

Compress the variance in a set of numbers?

I'm not sure if there's a better way to ask that, but I have a hovercraft which hovers by imparting force at each of four corners. I'd like to clamp the maximum variance between the thrusters so if ...
1k views

Rotating a vector by another vector in shader

I have a terrain surface with a normal for each point on the terrain. I have a second detail normal map to be applied to the terrain. These normals are in 3-space. The Y value of both normals is ...
3k views

Math topics for 3D graphics programming

I understand that the following math topics are required for 3D graphics programming. I have started doing some of them in my math course. Can someone point me in the direction of a resource that ...
482 views

Animated examples of different interpolations formulas: any link?

I remember having spotted a link to a huge page with different equations to non linear interpolation curves, for example if you want to stop a car smoothly, etc. Those can sometime be useful to ...
340 views

How do I find the largest circle possible in a square of pixels using Unity?

As I am using Unity, I can easily grab a square of pixels of any length. However, I want to find the largest circle possible within that square of pixels. So for instance, if I had a 40 x 40 square ...
300 views

Surface of Revolution with 3D surface

I have to use this function to get a Surface of Revolution (homework). newVertex = (oldVertex.y, someFunc1(oldVertex.x, oldVertex.y), someFunc2(oldVertex.x, oldVertex.y)); As far as I know (FIXME) ...
197 views

Preventing ties

I'm working on a simple game to rate a users' preference among several styles. There are C classes, and the game consists of R rounds of comparison. At each round, the user is presented a ...
953 views

Adding air drag to a golf ball trajectory equation

I'm developing a 2D golf game in VB.NET 2005, but I am stuck on how to implement air or wind drag that should affect the ball. Already I have these equations for projectile: Vo ...
565 views

Kepler orbit : get position on the orbit over time

I'm developing a space-simulation related game, and I am having some trouble implementing the movement of binary stars, like this: The two stars orbit their centroid, and their trajectories are ...
349 views

What exactly causes a surface to overlap another?

I cannot really figure out what causes one surface to overlap another. In a 3D engine I'm creating, my technique is failing in edge cases. My method is sorting the surfaces to be painted from the ...
2k views

A ball hits the corner, where will it deflect?

I need to brush up my trigonometry and hope you can help here with a simple mathematical model. Here is my model so far in the image attached. I am aware that the frame animation has other problems ...
364 views

Calculating camera zoom value (top-down)

I need some help in 'camera maths'. I have a birds eye view of two characters. One character is static and the other can move. I would like the camera to always show both characters in full and, in ...
238 views

Realistic damage

I'm looking for a good way to simulate damage, for example a weapon firing at a ship it would calculate the damage depending on layer type, weapon type, angle and similar what i need is a way to to ...
465 views

Get intersection of vector in the middle of the screen

My screen resolution is 640x480 and I have two Vector2 objects located at (10,10) and (600, 320). How can I connect these two objects and extend the line to encompass the whole screens width, how can ...
838 views

Equation for bouncing graph?

I basically want my camera in 3D move automatically. Currently, I have linear movement which is rather dumb, so I'd like to do a bouncing movement. However, what is a good equation for bouncing? I ...
2k views

How to create a perspective field of view matrix?

Hey, hello. I am learning a little of WebGL (OpenGL ES 2.0) through the http://learningwebgl.com tutorials, but it uses a third party library to create the View, Projection and transformation matrices ...
808 views

Arrays for a heightmap tile-based map

I'm making a game that uses a map which have tiles, corners and borders. Here's a graphical representation: I've managed to store tiles and corners in memory but I'm having troubles to get ...
9k views

Best C++ Math Library for Game Engine? [closed]

I'm looking for a fast opensource C++ math-library for my game engine with the following features: fast (sse?) vectors matrices quaternions suitable for both opengl and directx
215 views

Projecting onto different size screens by cropping

I am building a phone application which will display a shape on screen. The shape should look the same on different screen sizes. I Decided the best way to do this is to show more of the background on ...
3k views

building a game for different resolution phones

I am starting some tests for building a game on the Android program. So far everything is working and seems nice. However I do not understand how to make sure my game looks correct on all phones as ...
458 views

Calculating and detecting curves

How can I detect the 'steepness' of a curve? For example, if the user swipes their finger across the screen in a curve, what's the best way of detecting whether the curve is almost a semi-circle, or ...
850 views

Physics timestep questions

I've got a projectile working perfectly using the code below: //initialised in loading screen 60 is the FPS - projectilEposition and velocity are Vector3 types gravity = new Vector3(0, ...
428 views

Calculate the initial velocity of a 3D trajectory

I've got a 2D projectile code sample working, but would like to extend it to 3D. How would I calculate the initial velocity of the Z-axis? At the moment, I've got: initVel.X = (float)Math.Cos(45.0); ...
588 views

I asked a similar question recently but now I think I know more about what I really want to know. I can answer my own question if I get to understand this bit. I have a situation where a sprite's ...
1k views

2D shader to draw representation of rotating sphere

I want to display a 3D textured sphere, and then rotate it in one direction. The direction will never change, and the camera will never move. One way is to actually create a spherical mesh, map a ...
291 views

I'm not much of a maths expert, so this is probably quite straight forward. I was playing a soccer flash game where you take free kicks. You provide Power, Swerve and Direction. I'm reading up on ...
340 views

Blending animations for more character movements

I am making a hack n slash 3rd person game, and I want the character movements to be more dynamic not like fighting games where you have a moves list. I want to animate tons of different animations ...
247 views

Approximating walking physics via simpler sliding physics

I am modeling walking insects. I implement them as cuboids and use forces (including friction and drag), to control motion. However, the movement characteristics of this 'sliding box' physics don't ...
415 views

Building (simple) stellar systems

I'm currently looking at how to easily simulate some stellar systems (meaning some central stars and then some planets with maybe satellites), in order to allow later some space based strategy game ...
1k views

Atmospheric Scattering

I'm trying to implement atmospheric scattering based on Sean O`Neil algorithm that was published in GPU Gems 2. But I have some trouble getting the shader to work. My latest attempts resulted in: ...
332 views

Mandelbrot set not displaying properly

I am trying to render mandelbrot set using glsl. I'm not sure why its not rendering the correct shape. Does the mandelbrot calculation require values to be within a range for the (x,y) [ or (real, ...
2k views

Voronoi regions of a (convex) polygon

I'm looking to add circle-polygon collisions to my Separating Axis Theorem collision detection. The metanet software tutorial (http://www.metanetsoftware.com/technique/tutorialA.html#section3) on ...
545 views

Is there a common word that encompasses handling of position, rotation, and scale together?

I'm looking for a name for my class that manipulates 4x4 matrices that handle position, rotation, and scale. Is there a common word that encompasses all three? (I'm splitting the matrix math into its ...
5k views

Complete Math Library for use in OpenGL ES 2.0 Game?

Are you aware of a complete (or almost complete) cross platform math library for use in OpenGL ES 2.0 games? The library should contain: Matrix2x2, Matrix 3x3, Matrix4x4 classes Quaternions ...
4k views

How should I sort images in an isometric game so that they appear in the correct order?

This seems like a rather simple problem but I am having a lot of difficulty with it. What should I do to properly sort images in an isometric game? In a normal 2d top-down game one could use the ...
2k views

Changing coordinate system from Z-up to Y-up

Blender's coordinate system is different from what I'm used to, in that Z points upwards instead of Y. What would be the simplest way of converting all the world data (so that all animations, texture ...
984 views

How can I get a velocity vector for an object moving in a circle?

I am simply trying to make an object move in a circle around a point. Let's say I have an object with a position vector going from that point to the object, and also the angle of the object with the x ...
389 views

How to detect and collide two elastic line segments?

There are 4 moving physical nodes in 3D space. They are paired with two elastic line segments / strings (1 <-> 2; 3 <-> 4). Part I: How to detect the collision of two segments? Part II: On the ...
371 views

XNA - Weird bug with 2D Sprite Rotation

I have a problem with my XNA Game, I have a function where I need my sprite to face towards an enemy, using this code: Vector2 currentPosition = Position; Vector2 nearestEnemy = ...
254 views

Frenet frame and application

I have just been reviewing Frenet Frame math. It is an interesting geometrical issue. I know that common applications are: camera movement along a curve tube and ribbons surface Can someone ...
730 views

snapping an angle to the closest cardinal direction

I'm developing a 2D sprite-based game, and I'm finding that I'm having trouble with making the sprites rotate correctly. In a nutshell, I've got spritesheets for each of 5 directions (the other 3 come ...
2k views

Ray Intersecting Plane Formula in C++/DirectX

I'm developing a picking system that will use rays that intersect volumes and I'm having trouble with ray intersection versus a plane. I was able to figure out spheres fairly easily, but planes are ...
976 views

Basic tutorial/introduction for 3d matrices, idealy in c++, without openGl or directX

I am wondering if there is a simple tutorial that covers the basics of how to initialize rotation, translation and projection matrices, and how to multiply them, and how to get the screen coordinates ...