Questions tagged [matrix]

A 2D array of numbers, symbols or expressions, arranged in rows and columns. Each row must have the same number of columns. The numbers, symbols or expressions themselves are called elements or entries.

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Restoring projection matrix

I am learning to use FBOs and one of the things that I need to do when rendering something onto user defined FBO, I have to setup the projection, modelview and viewport for it. Once I am done ...
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2answers
101 views

How many matrices do i need to represent a rectangular figure and translate it?

I'm learning math at the moment and i can't really understand the purpose of the matrix. Yes, i've watched several tutorials out there and reading the book but still confused. Correct me if i'm wrong....
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What is the best way of storing transformations for an object and then applying them with OpenGL?

First some background info... I have been working on a platformer game, which I draw with OpenGL. The platforms are cubes and the player is a cube. The platforms and the player (both cubes) are ...
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350 views

DX11 Camera not working properly

I'm currently trying to implement a ArcBall Camera which should fly around a given XMFLOAT3 position stored in a cb with a spezified distance to the position. I used the code from Allen Sherrod for ...
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1answer
1k views

OpenGL Arc-Ball Camera Yaw Pitch GLM::Rotate

I'm currently working on a small Voxel-Editor Project. In the editor, I plan on using an Arc-Ball camera which rotate around the model. My camera is currently working but in an odd way. I can't seem ...
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1answer
106 views

Recap on how a camera works in 3d Space?

This may be marked as a duplicate, but I have been trouble thinking about a camera. I understand that there is a "camera transform," or view matrix. However, this is multiplied with every vertex in ...
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1answer
187 views

Rotating a 4D matrix about the Y axis with an X-Z vector

I should mention that I'm pretty new to Matrices and will probably need a layman's answer to my question. I have a 4D matrix which represents the rotation of an object in 3D space. I have a ...
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1answer
544 views

How to calculate if a point is contained in rectangular camera viewport with rotation?

I am working with my camera, and am trying to improve it so that I can calculate if a world point is on screen, taking rotation into account. Currently, my camera rectangle is calculated as so: ...
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3answers
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2D HLSL World position

I'm trying to get world position from my vertex shader to my pixel shader so that I can disable the shader once a preset X coordinate has been passed (no shading once I'm over X). Getting the screen ...
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1answer
537 views

XNA: How do I match Spritebatch View/Projection Matrices with BasicEffect Matrices?

I'm rendering a bunch of 2D content using SpriteBatches to a default XNA viewport. A simple 2D camera is used to move around the scene, which generates a ...
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1answer
169 views

Distort a quad with a World Matrix

Is it possible to distort a quad multiplying its vertices by a specific world matrix? See the picture to understand what kind of distortion I need: Please note, that the quad is in 3d space and I ...
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1answer
722 views

What is the correct multiplication order for a 2D matrix?

I'm currently trying to create a camera and entity/model matrix for my 2D game similar to that of Unity3D. I've already tried to find answers to this question on stackoverflow/gamedev but i couldn't ...
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1answer
140 views

Orthogonal projections question

I'm very VERY new into the game development world and I had just some slight trouble wrapping my head around something. We were told between classes just to think about how scaling matrices can ...
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1answer
897 views

How to rotate vertices of 2D shape using a transform matrix?

I am making a top-down 2D game and am currently working on implementing improved collision using SAT. I programmed a Shape class with a Vector2 center that is its position in world space. On top of ...
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2answers
345 views

How to use camera transformation without depending on (1,-1) scale during spriteBatch.draw()

I am creating a 2D platformer type game in XNA. I currently have a camera object, with a position/rotation/zoomlevel that I use to generate a transformation matrix to pass to SpriteBatch.Begin(). ...
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1answer
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Converting 3 axis vectors to a rotation matrix [closed]

I am trying to get a rotation matrix (in 3dsmax) from 3 vectors that form an axis (all 3 vectors are aligned by 90 degrees each other) Somewhere I read that I could build a rotation matrix just by ...
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1answer
132 views

Minimal Projection Matrix

i hope you can help me. I'm currently stuck at the creation process for projection matrices used by shadow maps. The problem is the following: I got the spot/directional light projectionmatrix/...
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1answer
376 views

Optimising skeletal animation

I am implementing a skeleton system for my latest game. I am using my own linear algebra classes which already have some optimisations, such as separate transformPoint and transformVector functions ...
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1answer
271 views

Camera not strafing (GLSL)

I use this code in my GLSL vertex shader, where v_position is the vertex position: gl_Position = v_position * u_camera; and ...
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1answer
3k views

Scaling along an arbitrary axis (Dealing with non-uniform scale)

I'm trying to build my own little engine to get more familiar with the concepts of 3D programming. I have a transform class that on each frame it creates a Scaling Matrix (S), a Rotation Matrix from ...
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1answer
256 views

Movement on the X an Z axis are combined?

This is probably a stupid question, but I'm trying to simply move a 3D object up, down, left, and right (Not forward or backward). The Y axis works fine, but when I increment the object's X position, ...
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1answer
112 views

Camera closes in on the fixed point

I've been trying to create a camera that is controlled by the mouse and rotates around a fixed point (read (0, 0, 0)), both vertical and horizontal. This is what I've come up with: ...
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2answers
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How to port animation from one skeleton to another?

While I need to do this in a Blender3D modeler script, the math should be similar for other modelers or realtime engines. Blender3D specific terminology: Armature = skeleton EditBone = rest pose bone ...
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1answer
777 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 (...
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1answer
315 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 ...
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1answer
177 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 ...
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1answer
284 views

Why doesn't the y Axis work with SuperBible frame reference or GluLookAt

I'm currently trying to understand how to use the GLFrame Class in the superbible book, and acording to the 4th edition of the book, the camera matrix derived from the Frame of reference class should ...
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1answer
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What are the “axes of a matrix” exactly?

I am currently learning about game engines, and for the engine math, there are functions called GetXAxis, GetYAxis, and GetZAxis that returned the X, Y and Z axes for a matrix. These functions return ...
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1answer
111 views

Issues with 2D Body/Limb system [closed]

In my game I have programmed Body and Limb classes. The Body is guaranteed to have an origin in the center of its sprite. The Body class has a List of children Limbs, each with their own offset. Every ...
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0answers
181 views

Unproject considering parallax depth

How can I take screen coordinates (or alternatively world coordinates on the 'primary' parallax plane) and find out what world coordinates they translate into when taking parallax depth into account? ...
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1answer
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How can I create a 2D camera with upscaling and translation?

I've computed a Viewport that is fair in size (a proper aspect ratio to the given device) and then I calculate my ScaleMatrix like so: ...
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2answers
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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 ...
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4answers
13k 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 ...
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2answers
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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 ...
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1answer
148 views

Finding islands from array

Say I have an two dimensional array with values 0 or 1. How would I construct an algorithm (preferably in C#) to work out which ones are separated or islands. The algorithm would transform the left 2d ...
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1answer
241 views

How does a 4x4 matrix represent an object in space and matrix lore?

I have been following some tutorials on how Matrix maths works, with adding, dividing, scaling, etc, but I am struggling to understand how the 4x4 matrix represents an object's position in space. ...
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2answers
859 views

How do I have to take into account the direction in which the camera is facing when creating a first person strafe (left/right) movement

This is the code I am currently using, and it works great, except for the strafe always causes the camera to move along the X axis which is not relative to the direction in which the camera is ...
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4answers
3k views

Orthographic Projection with variable FOV

We are building agame with orthographic view. The problem we face is the fact that with different resolution you can see different area of the game world. E.g. if you have higher resolution you can ...
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2answers
968 views

How do I create a view matrix that does not contain the camera translation?

I'm looking at this tutorial https://capnramses.github.io/opengl/cubemaps.html about half way down the webpage, there is a description of a vertex shader ...
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2answers
1k views

Matrix Rotation with three Angles

I want to rotate a form with three given angles fo each of the three axis. But the GLM rotation function takes only one angle and a vector as arguments. How can I ...
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1answer
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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 ...
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1answer
80 views

How to convert -1 to 1 coordinate back to screen coordinates?

Here is a question in which Questioner asks how to convert world coordinates to 1 to -1 coordinates like Opengl, I want to know how to do that in reverse, that given a coordinates between 1 and -1 (...
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2answers
330 views

Get the difference between 2 matrices

Hi I'm using C# and MonoGame, and have the world matrices of 2 objects. I need to get the difference between them, so I can ...
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2answers
795 views

OpenGL: Is it efficient ok to glPushMatrix, plMultMatrix, plPopMatrix for every object in my scene?

I'm very new to opengl, and I might not fully understand the openGL matrix projection stack thing. So, I have about 300 'objects' in my scene, each with their own position/rotation, and I want to ...
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1answer
735 views

Inline-Building a World (SRT) Matrix

Currently, to construct a world matrix, I have the following code: return FromScale(scale) * rotation.RotMatrix * FromTranslation(translation); However, this is ...
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1answer
316 views

Does a 2D Vector or 2x2 Matrix play any role in 2D Transformations?

I'm having trouble trying to figure out if a vec2 or mat2 class are used at all in transformations for 2D rendering. Vec2, apart from representing UVs, AFAIK, is relatively pointless in regards to ...
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2answers
184 views

Encode world matrix as 2 float4s?

On one of the slides of their presentation "Batch, Batch, Batch!" guys from NVidia suggest encoding animation matrices for pallet skinning into two float4s as: • axis/angle • translate/uniform ...
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What matrix operations do I perform to translate then rotate then translate then rotate?

In an android game I want to draw a running leg. To output the thigh I do something like: ...
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2answers
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Matrix rotation of a rectangle to “face” a given point in 2d

Suppose you have a rectangle centered at point (0, 0) and now I want to rotate it such that it is facing the point (100, 100), how would I do this purely with matrix math? To give some more specifics ...
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2answers
156 views

TRS Matrix between 2 points

I have got 2 Points in 3D Space whose TRS Matrix' from 0.0 to there current place is known. Now I want to change the Matrix of the left point so that the matrix of the right point combined with the ...

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