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.

188 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.
636 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 ...
305 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, ...
1k 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 ...
835 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 ...
250 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 ...
407 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 ...
402 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 ...
2k 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 ...
168 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 ...
3k 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 ...
227 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 ...
363 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 ...
576 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. ...
131 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 = ...
888 views

3D: First Person Movement

I've searched and searched for a solution today but haven't found one. I have a Camera with Vector3 and also the camera has an angle. If I use this: hero.position.x += speedX; hero.position.z += ...
336 views

Acceleration based on current speed?

The faster an object goes, the slower it will accelerate, going from 0 to 50 takes a lot less time then going from 50 to 100, How do I calculate that, though? EDIT: Extra details, This specific ...
162 views

Minimap Around Perimeter of Screen, Code Provided

What I'm essentially trying to do is what a lot of FPS's nowadays do in regards to their HUD. When an objective is off-screen, a small icon / symbol is shown on the perimeter of the screen, basically ...
351 views

I am creating a quad that starts as a single quad, then divides itself multiple times (from 1 -> 4 -> 16 -> 64 -> 256 etc) but I have encounted an issue. When I get to 64 sub divisions only 16 quads ...
515 views

Mathematics for Game Development Book

For someone with some background in maths, what is a good book about: The core mathematics for game development How these techniques are applied to common problems in game development In ...
250 views

Can someone explain this Pulsate code to me

// Pulsate the size of the selected menu entry. double time = gametime.TotalGameTime.TotalSeconds; float pulsate = (float)Math.Sin(time * 6) + 1; scale = new Scale(1 + pulsate * 0.05f,1 + pulsate * ...
143 views

Issues with Spherical Coords and gluLookAt

I am currently developing a game set in a planet(A sphere), in which my camera mostly works though some issues arise from this method: ...
156 views

Averaging Camera Position

I'm making a camera which tracks the player. I am using a basic algorithm to calculate a position for the camera relative to the player. Then I am taking an average of this over the last x number of ...
82 views

How to accurately score moving averages (indepenent of sampling window)

I'm developing a puzzle game, and coming up with a little trouble how to accurately create the 'score' for a particular player's solution. In this game a player creates a machine which generates ...
876 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 ...
796 views

XNA: How to Flip/Mirror a position over a custom vector?

I want to flip Horizontally my Sprite/Texture however the SpriteEffects.FlipHorizontally isn't cutting it for me as it just flips the texture in place. I want to flip the texture over a specified ...
890 views

How can I do fast Triangle/Square vs Triangle collision detection?

I have a game world where the objects are in a grid based environment with the following restrictions. All of the triangles are 45-90-45 triangles that are unit length. They can only rotate 90°. The ...
1k views

Calculation of Inertia Tensors

Bit of a complex and lengthy question that, I'll admit, I don't quite understand very well yet so I will try and explain as best as I can. Short Version: Is there a general c++/physx formula out ...
148 views

Directional and orientation problem

I have drawn 5 tentacles which are shown in red. I have drew those tentacles on a 2D Circle, and positioned them on 5 vertices of the that circle. BTW, The circle is never be drawn, I have used it to ...
364 views

Camera target point based on angles

I'm working on a test project to learn some basic OpenGL. Right now I'm trying to work on a "camera" with gluLookAt. My camera object is really simple, I have two vectors, one for the position and the ...
2k views

The normal vector to a plane ax+by+cz+d=0?

I am calculating the normal vector to a plane ax+by+cz+d=0 According to the book: The normal vector N is often normalized to unit length because in that case the equation d = N ⋅Q + D gives the ...
1k views

Optimized algorithm for line-sphere intersection in GLSL

Well, hello then! I need to find intersection between line and sphere in GLSL. Right now my solution is based on Paul Bourke's page and was ported to GLSL this way: // The line passes through p1 and ...
342 views

Rotating points on a circle

I have drawn a 2D circle in X,Y,Z. I wanted to draw something on specific vertices of that circle and I managed to do it. When I wanted to move the circle, I wanted the vertices to get the updated ...
738 views

Camera Rotation (for mouse look) with LookAt does not work as expected (Local/Global)

My code for rotating my 3D fps camera isn't working as expected. I expect that the X-axis does rotate with the Y-axis, but it ain't so. I made some pictures to explain it better, I think its doing ...
1k views

Applications of calculus?

I understand that basic calculus is applicable to game development, particularly physics. Problem is, I'm not entirely sure how. So, what can I use it for? I'm most concerned about what's on the AP ...
160 views

How do I make a vector exactly reach a line?

Let's say a vector starts at Point P and points in the direction of v. How do I make sure that this vector exactly reaches the line? Its end should be exactly on the line, and not cross it.
124 views

How to limit the distance of a point?

I'm making an Angry Birds like game and I need to limit the distance that the user can pull back the slingshot, how do I do this?
305 views

Getting the normals of a hemisphere?

I'm trying to calculate the normal for a hemisphere. I draw the hemi-sphere by this code: for(float phi = 0.0; phi < 1.567; phi += factor) { glBegin(GL_QUAD_STRIP); for(float ...
1k views

How do I calculate the normal of a plane defined using homogeneous coordinates?

I can define a plane in 3D space using three 3D points (p0, p1, p2) that all lie in the plane and that form a non-degenerate triangle. Calculating the normal of the plane is as simple as calculating ...
189 views

Vectors and corners of squares

I am having some problems with some vector math. Imagine a square and coming from each corner of the square is an invisible vector, which starts at the square's centre and ends at the edge of the ...
373 views

How do I create weapon attachments?

My question is; I am developing a game for XNA and I am trying to create a weapon attachment for my player model. My player model loads the .md3 format and reads tags for attachment points. I am able ...
196 views

How to make sure that a Point A moving in the direction V reaches at Point B?

Let say I have, Point A(X1,Y1) moving in the direction V(W, H). I need to make sure that it reaches B(X2,Y2). I think I need to subtract some value in Point A(X1, X2). But not know what? I also sure ...
173 views

Calculate the direction, From Outer Polygon Point to Inner Polygon inside Point

I was able to find the co-ordinates of inner Polygon using this trick. Need the co-ordinates of innerPolygon But, I have some problem in getting the direction from Outer Polygon Point to Inner ...
1k views

Zooming to point of interest

I have the following variables: Point of interest which is the position(x,y) in pixels of the place to focus. Screen width,height which are the dimensions of the window. Zoom level which sets the ...
89 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 ...
237 views

Constrained/penalized distance function

Assume a character is located on a n by n grid and has to reach a certain entry on that grid. Its current position is (x1,y1). Also on the same grid is an enemy with coordinates (x2,y2). Each step ...
1k 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 ...
1k views

Random Vector within a cone [duplicate]

I'm looking to create a random vector within a cone given the radius (base). It feels like I've been traversing through many pages on the internet and still I'm no further forward to getting an ...