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.
3
votes
3answers
891 views
Get angle in radians given a point on a circle
I'm working on a dial that rotates around a circle.
This dial should lets you mousemove anywhere in a circle to adjust the position of the dial to a point on the circle with the same angle as the ...
3
votes
2answers
6k views
Rotate vector by matrix?
If I have a Vector, say (1,1), how can I rotate it around the origin (0,0)?
I'm working in XNA if that helps.
3
votes
4answers
449 views
Vary speed of enemy smoothly
Hey. I'm trying to create an enemy that travels at a speed s on screen but I'm having trouble with trying to make the speed vary in a smooth motion. Basically, I can get the enemy to move at a ...
3
votes
2answers
223 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 # ...
3
votes
2answers
256 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 ...
3
votes
2answers
834 views
I am looking to create realistic car movement using vectors
I have goggled how to do this and found this http://www.helixsoft.nl/articles/circle/sincos.htm I have had a go at it but most of the functions that were showed didn't work I just got errors because ...
3
votes
2answers
479 views
When constructing an orientation matrix, are the rows of the matrix the axis?
When constructing an orientation matrix, are the rows of the matrix the axis?
The matrix is row-major and I'm multiplying vectors on the right (Mv). So, the matrix looks like
r0c0 r0c1 r0c2
r1c0 ...
3
votes
2answers
188 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 ...
3
votes
3answers
232 views
Generate a range of number with X being returned most of the time
I am attempting to write a RNG which returns a normal-like curve. For example, say I define X to be 4, I would like to generate a range of numbers from 1 to 8, but with 4 being returned most of the ...
3
votes
3answers
408 views
Spot the difference game design help
I'm thinking of making a spot the difference game. But immediately I stumbled over a problem. I'm thinking of storing a "difference area" in the form of a x,y coordinate. However, because on a ...
3
votes
1answer
1k views
Understanding log/exp formula for RPG experience
While looking for examples of RPG experience formulas I came across this one
How to create adjustable formula for RPG level up requirements?, and I would really like to figure it out because I don't ...
3
votes
3answers
3k views
Getting the angle between two objects?
I have a set of boxes which create a sort of path, they don't intersect very smoothy and to help that process I'm trying ot find a way to get an angle between them that can make it easier to generate ...
3
votes
1answer
2k 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 ...
3
votes
1answer
956 views
Normal transformation and homogeneous coordinates
I'm very confused about the math behind the model/affine transformation expressed in homogeneous coordinates.
Reading this article, I understood that a generic vector is transformed by multiplying it ...
3
votes
2answers
111 views
What kind of projection is ScreenX=X/Z, ScreenY=Y/Z?
I have an existing class which transforms 3D vectors and projects them on a 2D plane (Camera). The code is all written in C without help from an external library.
To project a single vector (X,Y,Z) ...
3
votes
1answer
256 views
Spherical to Cartesian Coordinates
Well I'm reading the Frank's Luna DirectX10 book and, while I'm trying to understand the first demo, I found something that's not very clear at least for me. In the updateScene method, when I press A, ...
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 ...
3
votes
1answer
161 views
Math behind simulating a simple light source for rotated rectangle?
Say I have a 2D Rectangle. By offsetting its position by x y and rendering a shadow by an offset, it gives the illusion of a shadow. If I rotate the rectangle Z degrees and try it with the same ...
3
votes
1answer
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 = ...
3
votes
2answers
288 views
How do you transform a vector to use another objects orientation?
I want to take a vector that is using world coordinates and position it using the orientation of an object. So, if the direction of the object is the z-axis, and the vector is (0,0,1), then the ...
3
votes
2answers
315 views
Methods to 'cull check' polys in OpenGL
A quick search through the web suggests there's quite a few methods of potentially detecting back-culled faces on the CPU.
The purpose of the check is to evaluate whether to performing other ...
3
votes
2answers
120 views
Discover x,y coordinates given set arc distance and rotation
I have a turn-based car simulation. My vehicles have a maximum speed they can travel in a round, as well as a maximum amount they can change their heading over the course of a round. Say, 20 meters ...
3
votes
1answer
282 views
2D Smooth Turning in a Tile-Based Game
I am working on a 2D top-view grid-based game. A ball that rolls on the grid made up of different tiles. The tiles interact with the ball in a variety of ways.
I am having difficulty cleanly ...
3
votes
3answers
134 views
Determining a point that reached another point
I have two points, one is moving and one is stationary. I would like to know if the moving point has reached that point or not. I tried to calculate the distance between two vectors and the distance ...
3
votes
4answers
451 views
How to draw a line of a given length towards a given object?
I wanna draw a line between two moving objects
I can't use:
cDrawLine(startPointCG, endPointCG);
because the line must have a length. So I'm trying to measure the angle between those two points ...
3
votes
4answers
1k views
non-linear interpolation
I have an object, and i want to interpolate its position between two points over a given time period; but i dont want it to be a linear interpolation. I'm not sure if i'm phrasing this right.
vector ...
3
votes
3answers
589 views
Restrict movement within a radius
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 ...
3
votes
3answers
291 views
Adding 'swerve' to a direction
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 ...
3
votes
5answers
511 views
How to randomly place rectangle inside a larger bounding rectangle without intersecting other rectangles inside
Let us consider the case: there is an overall bounding rectangle (call this Rb) which contains a number of rectangles within it (call this set SRo). Now I would like to randomly position a new ...
3
votes
2answers
205 views
Rotating voxels in 3d space amongst the x axis
I have a very simple voxel engine and so far it works based on coordinates, e.g. x, y, z. I was wondering if there is a formula for rotating groups of voxels/coordinates from the x axis(e.g. [0, 1, ...
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 ...
3
votes
3answers
822 views
How do I find the angle required to point to another object?
I am making an air combat game, where you can fly a ship in a 3D space. There is an opponent that flies around as well. When the opponent is not on screen, I want to display an arrow pointing in the ...
3
votes
2answers
491 views
How to achieve hologram projection effect with head tracking
I want to recreate this:
http://www.youtube.com/watch?v=9xMSGmjOZIg&feature=related
I can take care of tracking the user's head, and in one of the comments I believe the author says that he used ...
3
votes
1answer
412 views
How do you get an object to orbit around a certain point on a 2d plane?
I had a concept for a game come to me this morning but I can't figure out how I'd go about implementing the movement.
The general idea involves the left and right controls causing a sprite to go ...
3
votes
3answers
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 ...
3
votes
4answers
316 views
Forcing one projectile to follow close behind an initial projectile
I'm shooting out a projectile and I want another projectile to closely follow it. I can't simply shoot out the second projectile at a slightly lesser time because the first projectile may change ...
3
votes
2answers
293 views
3D rotation matrices deform object while rotating
I'm writing a small 3D renderer (using an orthographic projection right now).
I've run into some trouble with my 3D rotation matrices. They seem to squeeze my 3D object (a box primitive) at certain ...
3
votes
1answer
199 views
D3DXMatrixDecompose gives different quaternion than D3DXQuaternionRotationMatrix
In trying to solve this problem, I tracked down the problem to the conversion of the rotation matrix to quaternion. In particular, consider the following matrix:
-0.02099178 0.9997436 -0.008475631 0
...
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 ...
3
votes
2answers
84 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
2answers
2k views
Basics of drawing in 2d with OpenGL 3 shaders
I am new to OpenGL 3 and graphics programming, and want to create some basic 2d graphics. I have the following scenario of how I might go about drawing a basic (but general) 2d rectangle. I'm not ...
3
votes
3answers
3k views
How to get translation from view matrix
How can I retrieve the camera's world-space position from its view matrix?
The only answers I've seen to this question suggest the translation is in the last row/col but this wouldn't work since the ...
3
votes
2answers
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 ...
3
votes
1answer
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 ...
3
votes
1answer
278 views
Drawing isometric walls
I'm having some trouble with isometric walls.
I'm drawing isometric floor tiles using the back to front rendering method, and it works fine. I also keep my floor tiles lined up properly in a nice ...
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 ...
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 ...
3
votes
2answers
558 views
Python float 32bit to half float 16bit
I'm trying to write a 3D model exporter addon for Blender in Python and need some help.
The spec of the 3D format uses some compression on the vertices, there is a vertex buffer that contains ...
3
votes
1answer
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, ...
3
votes
1answer
61 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 ...
