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.
1
vote
2answers
486 views
Rotating a polygon around it's center
I have drawn a ship using three lines, and would like to rotate the ship around its axis in opengl, I have tried the following, but the ship translates while rotation!.
void Ship::Draw( )
{
...
3
votes
3answers
132 views
Help understanding the order of vector subtraction
I always struggle with intuitively figuring out the order of subtraction in multiple situations for example
The difference between the current mouse coordinates and the last frame's coordinates
The ...
0
votes
1answer
260 views
Rotation matrices from Quaternion.Identity and -Quaternion.Identity are the same?
If I create a rotation matrix from an identity quaternion then it is the same as a creating it from a negative identity quaternion
Matrix m0 = ...
0
votes
1answer
296 views
Implementing framerate independence
I know the following line of code has the effect of moving 3 units per milliseconds independent of framerate, but my sucky mathematical intuition is unable to understand WHY this works
translation *= ...
1
vote
2answers
246 views
Find the nearest control points either side of a Catmull Rom spline segment
There is a formula for evaluating a Catmull Rom spline segment at time 't' found here.
The problem with this is that it requires finding the two control points either side of the segment to evaluate.
...
0
votes
1answer
146 views
Question about Target parameter of Matrix.CreateLookAt
I have a newbie question that's causing me a little bit of confusion when experimenting with cameras and reading other peoples implementations - does this parameter represent a point or a vector?
In ...
0
votes
1answer
181 views
Optimizing hierarchical transform
I'm transforming objects in 3D space by transforming each vector with the object's 4x4 transform matrix. In order to achieve hierarchical transform, I transform the child by its own matrix, and then ...
0
votes
2answers
248 views
3D Vector “End Point” Calculation for procedural Vector Graphics
Alright, So I need some help with some Vector Math.
I've developing some game Engines that have Procedural Fractal Generation for Some Graphics, such as using Lindenmayer Systems for generating Trees ...
3
votes
1answer
291 views
Finding closest object to a location within a specific perpendicular distance to direction vector
I have a location and a direction vector indicating facing, I want to find the closest object to that location that is within some tolerance distance (perpendicular distance) to the ray formed by the ...
0
votes
3answers
402 views
Checking for collisions on a 3D heightmap
I have a 3D heightmap drawn using OpenGL (which isn't important). It's represented by a 2D array of height data. To draw this I go through the array using each point as a vertex. Three vertices are ...
6
votes
1answer
190 views
Matrices: Arrays or separate member variables?
I'm teaching myself 3D maths and in the process building my own rudimentary engine (of sorts). I was wondering what would be the best way to structure my matrix class. There are a few options:
...
2
votes
1answer
144 views
Game speed cubic growth
Is it possible, using delta in my update method to increase a game speed variable exponentially on cubic growth (the blue line below)
My maths isn't great so I'm not sure how the formula would be ...
5
votes
2answers
206 views
Robust line of sight test on the inside of a polygon with tolerance
Foreword
This is a followup to this question and the main problem I'm trying to solve. My current solution is an hack which involves inflating the polygon, and doing most calculations on the inflated ...
3
votes
3answers
190 views
Adding tolerance to a point in polygon test
I've been using this method which was taken from Game Coding Complete to detect whether a point is inside of a polygon. It works in almost every case, but is failing on a few edge cases, and I can't ...
0
votes
3answers
355 views
Game Institute Math Courses
I'm 21 years old and I suck at math, I mean really bad. I don't have the necessary logic to apply it towards programming. I would like to learn the math and logic of applying it. I found Game ...
3
votes
1answer
301 views
Is it possible to procedurally place objects in a non-gridded game?
I'd like to implement procedural world generation, but I don't want it to look gridded or blocky, where everything is obviously placed on an integer grid.
I know that you can do this in gridded ...
1
vote
1answer
140 views
Math major as a viable degree
While I realize there are many topics about CS vs software engineering vs game school programs, I haven't found anything relating to whether pure math degrees (with CS minor and electives) would also ...
0
votes
1answer
746 views
as3 3D camera lookat
I'm making a 3D camera scene in Flash, draw using drawTriangles() and rotated and translated using a Matrix3D. I've got the camera to look after a specific point, but only on the Y-axis, using the x ...
2
votes
1answer
431 views
When to use Euler vs Axis angles vs Quaternions?
I understand the theory behind each but I was wondering if people could share their experiences in when one would use one over the other
For instance, if you were implementing a chase camera, a ...
0
votes
1answer
176 views
Why does multiplying texture coordinates scale the texture?
I'm having trouble visualizing this geometrically - why is it that multiplying the U,V coordinates of a texture coordinate has the effect of scaling that texture by that factor?
eg if you scaled the ...
-1
votes
1answer
150 views
Camera not working
I made a camera in DX9. To move forward I press the Up arrow. To rotate on the Y axis I use the mouse. When I perform these movements on their own the camera moves at the speed I want.
However, if I ...
2
votes
2answers
144 views
Get all triangles that are < N dist from you?
Does anyone know of a way I could add a radius to this code for p? Like basically saying "this is true if the triangle is < N dist from the point"
public boolean isPointInTriangle( Vector3f p, ...
0
votes
2answers
131 views
How to balance this Pokémon simulator metagame by feedback?
This is a Pokémon simulator where you build a team of 6 pokémon and battle with someone. Unfortunately, some Pokémon are stronger than others and only a few of the hundredth species are practical. I'm ...
8
votes
3answers
1k views
How to move an object along a circumference of another object?
I am so out of math that it hurts, but for some of you this should be a piece of cake.
I want to move an object around another along its ages or circumference on a simple circular path. At the moment ...
2
votes
1answer
213 views
Transform 3D vectors between coordinate systems
I've got 6 points in 3D space: A,B,C,D,E,F, that represent 4 vectors. AB is perpendicular to AC and DE is perpendicular to DF.
I need to find a transformation matrix M, that transforms AB to DE and ...
0
votes
0answers
125 views
way to do if(x > x2) x = x2 with rotation?
Alright, so I got this walking code, and some collision detection, now the collision detection returns a Vector3f of the closest point on the triangle that the projected position is at (pos + move), ...
4
votes
2answers
279 views
Estimate angle to launch missile, maths question
I've been working on this for an hour or two now and my maths really isn't my strong suit which is definitely not a good thing for a game programmer but that shouldn't stop me enjoying a hobby surely?
...
3
votes
1answer
311 views
Smoothing rotation
I've spent the last three days trying to work out how to rotate a sprite smoothly depending on the velocity.x value of the sprite. I'm using this:
float Proportion = 9.5;
float maxDiff = 200;
float ...
6
votes
2answers
230 views
Elliptical orbit modeling
I'm playing with orbits in a simple 2-d game where a ship flies around in space and is attracted to massive things. The ship's velocity is stored in a vector and acceleration is applied to it every ...
2
votes
2answers
199 views
how to transform child elements position into a world position
I'm making a 2d space game in Javascript with canvas. In this game there's a bunch of spaceships, positioned in world space, with turrets, positioned relative to their parent ships. These objects also ...
2
votes
1answer
258 views
Position Reconstruction from Depth by inverting Perspective Projection
I had some trouble reconstructing position from depth sampled from the depth buffer. I use the equivalent of gluPerspective in GLM. The code in GLM is:
template
GLM_FUNC_QUALIFIER detail::tmat4x4 ...
1
vote
1answer
603 views
Interpolation between two 3D points?
I'm working with some splines which define a path a character follows (you can see a gameplay video here to get a better understanding of what's going on: http://www.youtube.com/watch?v=BndobjOiZ6g). ...
-1
votes
1answer
274 views
How do I convert sin, cos and tan into an int in Java?
How would you be able to change Math.sin, Math.cos and Math.tan into an int?
This is because I heard that it is useful to have those Math resources in movement, gravity, etc. in gaming.
Also, as a ...
1
vote
2answers
1k views
How would I translate screen coordinates to Isometric coordinates?
I have a function isoToScreen(x, y) that converts Isometric coordinates to Screen coordinates.
var tileW = 16;
var tileH = 16;
var isoToScreen = function(x, y) {
var posX = (x - y) * tileW;
...
2
votes
2answers
359 views
How much does game development mathematics change over time?
This question is mainly aimed at this book, Essential Mathematics for Games and Interactive Applications, Second Edition which I have seen highly recommended all around the internet, so I'm sure there ...
-3
votes
2answers
165 views
Calculating AABB's Origin
I can't work out how to find the position in which my AABB should be corresponding to my object.
2
votes
1answer
384 views
Is it possible to billboard a sprite using a transformation matrix?
None of the current topics on billboarding seemed to answer this question.
But, given
a sprite (or quad) that has it's own 4x4 transformation matrix
a camera with a view matrix (a standard 4x4 ...
2
votes
2answers
224 views
Best way to calculate unit deaths in browser game combat?
My browser game's combat system is written and mechanically functioning well. It's written in PHP and uses a SQL database. I'm happy with the unit balance in relation to one another. I am, however, ...
1
vote
0answers
655 views
Orthographic Camera Zooming
In XNA I am using a spritebatch to render a board. I have created a camera class which can provide me a view and projection matrix. Currently I am supplying the view matrix to my sprite batch when I ...
2
votes
2answers
579 views
How to rotate an object so it stands correctly (back always facing the camera)
I have the following scene:
And I have two 3D vectors, the camera position, and the focus position. The focus vector is always behind the monster. I know how to rotate the camera around the focus ...
1
vote
1answer
186 views
How can I more efficiently write my Math-Code in AS3
So this might be an odd question to ask. But I'm not really the biggest mathematician out there, and I have a weird habit of writing code. So I'm going to post what I'm working on. I'm doing a ...
1
vote
3answers
375 views
Missing z-axis rotation for transforming between two vectors
I'm trying to rotate a cube so that it's facing up, but am getting hung up on the final implementation details. It now reliably will rotate the x,y axis to the correct side, but the z-axis is never ...
2
votes
1answer
308 views
Silly question about perspective correct texture mapping
OK, I'll admit, the math on a perspective projection matrix is quite hairy for me, but I get the general gist of it: morph the object so that it looks... perspective-ish.
But there is one thing which ...
13
votes
1answer
1k views
What are the maths behind 'Raiden 2' purple laser?
The path of the laser is affected by user input and enemies present on the screen.
Here is a video, at 5:00 minutes the laser in question is shown : Raiden II (PS) - 1 Loop Clear - Part 2
UPDATE
...
3
votes
2answers
154 views
Camera placement sphere for an always fully visible object
Given an object:
With the bounds [x, y, z, width, height, depth]
And an orthographic projection [left, right, bottom, top, near, far]
I want to determine the radius of a sphere which allows me to ...
2
votes
3answers
2k views
Getting isometric grid coordinates from standard X,Y coordinates
I'm currently trying to add sprites to an isometric Tiled TMX map using Objects in cocos2d. The problem is the X and Y metadata from TMX object are in standard 2d format (pixels x, pixels y), instead ...
3
votes
2answers
205 views
Angle range detection
I'm trying to make game like portal which players can transform between two holes.
My problem is, how to detect if player's have the right angle to the hole. (hole has an angle to a direction, if ...
0
votes
2answers
292 views
Collision, then what?
I know how to check collision for example 2 spheres. But my question is how do I use the collsion response in a good way?
How do I make my character unable to walk in to the Sphere? I've got to the ...
1
vote
2answers
440 views
Rotate 3D cube so nearest side is facing user
How do I figure out the new angle and rotation vectors for the most visible side of the cube?
Why: The user can rotate cube, but when finished I'd like the cube to snap to a side facing the user.
...
0
votes
0answers
94 views
What is the connection between an isometric angle and scale
I am trying to work out an isometric projection matrix for a custom angle.
In the engine I'm using there's a projection matrix defined like so:
projection.rotate(45 * (Math.PI / 180) );
scale = ...
