An array of numbers, symbols or expressions, arranged in row and columns. The numbers, symbols or expressions themselves are called elements or entries.

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10
votes
1answer
2k views

Screen space to world space

I am writing a 2D game where my game world has x axis running left to right, y axis running top to bottom, and z axis out of the screen: Whilst my game world is top-down, the game is rendered on a ...
2
votes
1answer
8k views

Transform between two 3d cartesian coordinate systems

I'd like to know how to get the rotation matrix for the transformation from one cartesian coordinate system (X,Y,Z) to another one (X',Y',Z'). Both systems are defined with three orthogonal vectors as ...
1
vote
4answers
5k views

Transform coordinates from 3d to 2d without matrix or built in methods

Not to long ago i started to create a small 3D engine in javascript to combine this with an html5 canvas. One of the issues I run into is how can you transform 3d to 2d coords. Since I cannot use ...
2
votes
2answers
490 views

3D Translation using only distance and angles

So I'm starting to foray into 3D game programming, but I've hit something of a snag. I have an object I want to move around. It should always move either forward or backward relative to its local Z ...
3
votes
2answers
543 views

Trying to understand 2D vector -> projection space conversion

I'm trying to understand how I can transform 2D vectors (x, y) to projection space. Something hasn't quite clicked for me yet. As per my previous question, here's the effect I'm trying to achieve: ...
0
votes
3answers
270 views

Project rendering onto a polygon in the scene

I have a function that renders a simple OpenGL scene. I want to display this scene on a polygon within another scene, without the function having to know about it. For example, to display the scene on ...
6
votes
2answers
2k views

Matrix for 2D perspective

I'm trying to determine whether what I'm attempting to achieve is even possible mathematically. I'm obviously not a seasoned game developer so I'm having trouble even coming up with the terminology to ...
3
votes
1answer
1k views

How do I know if a perspective matrix is right or left handed coordinate system?

For example, if I define my perspective matrix as the following: m[0] = 1.f / ( aspect * focalLength ); m[5] = 1.f / focalLength; m[10] = -zFar / (zFar - zNear); m[11] = -1; m[14] = ...
6
votes
3answers
955 views

Arbitrary projection matrix from 6 arbitrary frustum planes

A projection matrix represent a tranformation from the camera view space to the rendering system clip space. In other words, it defines the transormation between a 6-sided frustum to the clip cube. ...
1
vote
1answer
877 views

Translating local to global coordinates in ARToolkit / OpenGL

Ok, so I've tried reading over the other questions and something's just not clicking for me. I am working on an augmented reality application using ARToolkit, however it should just be straight ...
1
vote
2answers
880 views

Transformation order when dealing with Meshes

I have created a player model out of primitive types. To do this I have created a Model class and Component (mesh) class. Each model consists of one or more components my problems start when you have ...
1
vote
1answer
336 views

How to prevent 2D camera rotation if it would violate the bounds of the camera?

I'm working on a Camera class and I have a rectangle field named Bounds that determines the bounds of the camera. I have it working for zooming and moving the camera so that the camera cannot exit its ...
2
votes
2answers
898 views

What is the difference between Vector2.Transform and this method?

I've been working on some steering behaviors and ran into trouble with my logic for converting points in world space into points in local space. I had this (it's not optimized for multiple points yet, ...
2
votes
1answer
391 views

How do you extract a Vector3 positions only from a world matrix in an array of positions (from Kinect)

've just started building a physical camera class for the depth data you get from a Kinect. I have a Vector3 array of [imageWidth, imageHeight] describing the LOCAL positions I get in from the kinect ...
3
votes
1answer
390 views

Confused about order of operation when using a Matrix in XNA, C#

Here are two different pieces of code This is what I started with Vector2 hold = Vector2.Transform(pos1, mat1); Matrix inv = Matrix.Invert(mat2); Vector2 pos2 = Vector2.Transform(hold, inv); And ...
2
votes
1answer
1k views

How can I use a 3x3 matrix within a 4x4 matrix representation?

In XNA there is only one Matrix class which is actually 4x4 matrix. How to use it to represent a 3x3 matrix? I am trying to represent the inertia tensor of a body which is a 3x3 matrix, so I have ...
2
votes
1answer
422 views

How to linearly transform vertices for large coordinate systems

Alright, so I'm working on a space game and well, I want it to have a lot of space! So I need a large coordinate system and for my rendering pipeline to not suffer from "vertex jittering" due to ...
1
vote
1answer
419 views

Strange 3D game engine camera with X,Y,Zoom instead of X,Y,Z

I'm using a 3D game engine, that uses a 4x4 matrix to modify the camera projection, in this format: r r r x r r r y r r r z - - - zoom Strangely though, the camera does not respond to the Z ...
5
votes
2answers
985 views

What's a pre-multiplied 4x4 matrix?

I'm using a 3d game engine, that uses a 4x4 matrix to modify the camera projection. The matrix is in the regular 4x4 format: r r r x r r r y r r r z - - - zoom The description for the ...
4
votes
3answers
5k 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 ...
2
votes
1answer
454 views

Transformed Pretransformed coordinates?

I am creating a minecraft like terrain engine thing in XNA and C#, and I am trying to create a item/block selector tool. The thing is I would like to have 3D objects on the tool. So I thought for the ...
4
votes
1answer
346 views

Getting the Bounds of a 2D Cameras View with Zoom

I am using a 2D camera, which does rotations and zoom. Currently, I am using the following to get my MinX, MinY, MaxX and MaxY... public float MinX { get { return ...
3
votes
1answer
1k views

Can a 4x4 matrix describe a camera's perspective?

I'm working with a closed-source 3D engine, and it only allows you to set the view projection via a 4x4 matrix. Can this matrix describe the camera's translation, rotation & perspective? I turned ...
2
votes
2answers
1k views

How can I transform a point from world space to object space?

If I have an object space described by transformation matrix that should be applied to object to transform it to world space, what I have to do to transform point (world space) to that object space. ...
2
votes
1answer
675 views

How to create projection/view matrix for hole in the monitor effect

Lets say I have my XNA app window that is sized at 640 x 480 pixels. Now lets say I have a cube model with its poly's facing in to make a room. This cube is sized 640 units wide by 480 units high by ...
7
votes
3answers
1k views

How do I adjust the origin of rotation for a group of sprites?

I am currently grouping sprites together, then applying a rotation transformation on draw: private void UpdateMatrix(ref Vector2 origin, float radians) { Vector3 matrixorigin = new ...
1
vote
1answer
2k views

matrix 4x4 position data

I understand that a 4x4 matrix holds rotation and position data. The rotation data is held in the 3x3 sub-matrix at the top left of the matrix. The position data is held in the last column of the ...
2
votes
1answer
224 views

Translating an object along its heading

Solved! I was not applying the transformations in the proper order. I am working on a simulation that requires me to have several objects moving around in 3D space (text output of their current ...
2
votes
1answer
356 views

How do I build a matrix to translate one set of points to another?

I've got 3 points in space that define a triangle. I've also got a vertex buffer made up of three vertices, that also represent a triangle that I will refer to as a "model". How can I can I find the ...
6
votes
3answers
768 views

Why is my model's scale changing after rotating it?

I have just started a simple flight simulator and have implemented Roll and pitch. In the beginning, testing went very well; however, after about 15-20 seconds of constantly moving the thumbsticks in ...
3
votes
1answer
525 views

Better data structure for a game like Bubble Witch

I'm implementing a bubble-witch-like game (http://www.king.com/games/puzzle-games/bubble-witch/), and I was thinking on what's the better way to store the "bubbles" and to work with. I thought of ...
4
votes
1answer
370 views

UVW: better explanation, and how to implement with GLES texture2D()

UVW texture coordinates, as opposed to UV texture coordinates, do not get very adequate explanation on the web. Many people offer the simple exlanation, "UV is for 2-dimensional textures and UVW are ...
9
votes
2answers
5k views

How can I rotate about an arbitrary point in 3D (instead of the origin)?

I have some models that I want to rotate using quaternions in the normal manner, except instead of rotation about the origin, I want it to be offset slightly. I know that you don't say, in 3d space, ...
4
votes
2answers
832 views

Ara matrices calculated on the GPU or on the CPU? Would built-in matrix functions be faster than my custom ones?

If I add a math library (for example containing a Matrix class) and use it in my program drawing with OpenGL, will my be work slower than if I used standard OpenGL functions for matrix calculations? ...
7
votes
5answers
2k views

Can someone explain the (reasons for the) implications of colum vs row major in multiplication/concatenation?

I am trying to learn how to construct view and projection matrices, and keep reaching difficulties in my implementation owing to my confusion about the two standards for matrices. I know how to ...
6
votes
2answers
1k views

Vector games (Wireframe, Elite-like) theory and implementations?

I'm interesting in knowing more about how vector games like Elite and Star Wars Atari were built from grounds up. The question is not how to implement vector graphics with modern 3D APIs like OpenGL ...
8
votes
3answers
1k views

Should I use a world matrix?

Image reference for the question: (image from the CG tutorial) The D3D9 API got us used to world matrices. However, if you use world matrices, then you have to do an extra matrix multiply in the ...
2
votes
2answers
1k views

How should I calculate world and projection matrices in this scenario?

I'm trying to understand transformation matrices. Suppose I use the camera from this StackOverflow answer, this is how my view matrix would look: Matrix.Identity * ...
2
votes
1answer
533 views

COLLADA: Inverse bind pose in the wrong space?

(Crosspost from StackOverflow) I'm working on writing my own COLLADA importer. I've gotten pretty far, loading meshes and materials and such. But I've hit a snag on animation, specifically: joint ...
0
votes
1answer
847 views

How to find which side of a collider has been hit from hit.normal?

In Unity3d, i can get the normal of the surface with which the collider collides using hit.normal, but is there a way to find which side has been hit what is provided bu Unity3d? One solution is to ...
2
votes
2answers
3k views

gluLookAt vs glTranslate + glRotate and camera transformation matrices

I'm getting my hands dirty in OpenGL and something is bothering me a bit. It's my understanding from reading about the subject that a call to gluLookAt basically multiplies a matrix on the stack that ...
22
votes
1answer
22k views

What is the correct order to multiply scale, rotation and translation matrices for a proper world matrix?

Assume DirectX as the platform, if that is important. (Pretty sure it isn't) Assuming I have a proper scale, rotation and translation matrix, in what order do I multiply them to result in a proper ...
6
votes
3answers
2k views

XNA 4.0: 2D Camera Y and X are going in wrong direction

I asked this question on stackoverflow but assumed this might be a better area to ask it as well for a more informed answer. My problem is that I am trying to create a camera class and have it so ...
1
vote
1answer
1k views

XNA 2D Transform Matrix Scale at Zoom Question

This is the complete code I am currently using for my camera. It is incomplete and only partially understood by me (I am working off an example), but I have managed to hack some functionality with ...
6
votes
3answers
2k views

Direct3D and OpenGL Matrix representation

As I read in OpenGL matrices are column major. It means that if I create a 16 element array first four elements are the first column in matrix. Is it the same for Direct3D or any transformation's ...
8
votes
1answer
525 views

Downprojecting an imaginary 4D mesh to the screen

As a mental exercise, I'm trying to imagine projecting an arbitrary 4D mesh onto the screen (2D). I'm guessing a single 4D triangle would still consist of only 3 points, however each of those 3 ...
1
vote
1answer
196 views

Mesh to world vector translation

Suppose I have a world defined in typical OpenGL coords.. then the up vector defined for this space is (0,1,0). Now, if I load a model that is defined with (0,0,1) as its up vector, what are the ...
2
votes
1answer
169 views

Integration of homogenous wave

I have a 2D matrix; each of its elements describes a homogenous coordinate in 3D wave (the values of wave coordinates are changed in time). The wave rendering is done with texture. I need to make an ...
6
votes
2answers
877 views

What is eigenvalue decomposition and why would it be useful in games?

In various math libraries developed for game engines, I see 2x2 and 3x3 square matrices having this function (along with some helper functions). I tried to find information regarding it but did not ...
5
votes
2answers
443 views

Is a dynamic enviroment map using pincushion curvilinear perspective projection possible?

I'm wondering if it is possible to generate a dynamic spherical environment map using a single frame render using a pincushion curvilinear perspective projection matrix (phew, that's a mouthful)? ...