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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The perspective projection change the sign of z

I have an issue, I am drawing a cube in 3d. I am using z-buffer for hidden surfaces removal. But the hidden faces are drawn (i see the inside of the cube). After some research And I found that this ...
63 views

So I'm trying to figure out the model, view and projection matrices. I can, with some effort, find my drawings (3x3x3 structure of cubes) in 3D space and it looks like: The problem is, the cubes seem ...
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Custom matrix structure with OpenGL shaders

I have a MAT4 structure. ...
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Matrix parent-child transformation for 2D positioning

I am working with matrix math for parent / child transformations. I have to modify existing calculations to keep child scale constant while also keeping child position relative to its parent. Here's ...
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OpenGL, How should I pass the matrix using VBO and binding points?

I'm trying to make a simple example in OpenGL and C++ to draw a square and change position and size through an array. my problem lies precisely in the passage of the matrix to the shader. I initially ...
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Camera rotation in TouchDesigner

I need help on something I'm struggling with very much. I am working on a TouchDesigner patch where I have a Camera COMP with rotation on x, y and z axes. I need the formulas to convert such rotations ...
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Dimetric Screen to World coordinates

I've got a successful projection of world coordinates to the screen, but when I try to generate a ray for screen coordinates to the world, it always generates a fixed point which is invalid. I started ...
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How can I calculate vertex positions for a rectangle outline using a unit square, vertex normals, model matrix and outline thickness?

I'm trying to draw a hollow rectangle (i.e. the border of a rectangle without the middle) using a unit square plus normals. The actual positions are being calculated in my vertex shader. For example, ...
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invert:condition "det==0" is true error with no obvious cause

For my project I am turning my CharacterBody3D 90 degrees on the x-axis towards a wall. To achieve this I set basis.Z to the <...
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How to make calculating the inverse matrix more robust?

When I calculated the inverse matrix, I found that the error in using the float data type would cause the inverse matrix calculation error. Is there any good solution? ...
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How to obtain the Position on the screen (Vector2) of the Position of an object in the world (Vector3)?

I have been searching around for a solution to this but still haven't been able to use it or find it, the thing is i need the Screen Position of an object that is being seen, for this i have three ...
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Is this gimbal lock I'm hitting even with rotation matrices / quaternions?

I'm spawning a trigger box relative to another object using local offset. The engine I'm using does not provide a native function to make that conversion (at least in a way accessible to me), so I am ...
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When does normalization happen in the perspective projection matrix

I am currently watching this video where the instructor shows how the perspective project matrix is actually derived. There are a few things that I am still unclear of. Firstly he says we need to ...
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How do I create a localtoworldmatrix and worldtolocalmatrix in Godot?

From what I can tell Godot uses Projection for 4x4 matrixes, but I see no way to generate a localtoworldmatrix from a given transform in Godot, how do I do this?
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Relationship between matrix storage order and matrix notation?

This is how I (possibly mistakenly) understand it. Please correct me if I am wrong. Assuming a 4x4 matrix composed of vectors v0 through v3 is stored in a one-dimensional array with indices [00] ...
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Rotate UVs in shader and contains result into quad with repeat edge pixels

I ask for help - I need to rotate the UV scan inside the quad by a certain angle (set by a parameter) so that the result is embedded in the original UV, and the missing areas are repeat edge pixels. ...
80 views

How to correctly rotate 2D orthographic projection around a central point?

I want to rotate a 2D orthographic projection around the centre point of my view. However, something is off (it looks like a translation) but I'm not sure what. To put some concrete values on the ...
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Isometric camera lookat

I'm trying to make my isometric camera follow my player or lookat any other object projection matrix is ...
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Inertia Tensor Relative to Center of Mass vs Inertia Tensor in Body Coordinates

If I have the inertia tensor relative to the center of mass, is that the same as the inertia tensor in body coordinates? If no, can you please explain the difference and how do I numerically calculate ...
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I am trying to implement a program in Direct3D 11 which uses techniques like deferred shading and shadowmapping, but when I create my gBuffers, the position looks strange. After researching a bit I ...
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How to set up view and model matrices for 3D rendering?

For various reasons I am building a very simple graphics engine. I have a pretty good 2D thing using plain SDL2 and C that essentially boils down to a single "putpixel" function. I can ...
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Error in directional light shadow projection matrix

I have VC++ code for DX9 that draws shadows perfectly. ...
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Align two meshes given 2 faces

I have two meshes (A and B) and I know that a triangle in A has the same size and same angles as a triangle in B. For simplicity, suppose A is an octahedron and B is a tetrahedron. And suppose the ...
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1 vote
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Implementing a Maya-like orbit camera in Vulkan/OpenGL

I want to create an orbit camera with zooming, panning, and rotation. I used the following examples to create cameras: https://stackoverflow.com/questions/54400422/how-to-implement-altmmb-camera-...
685 views

Calculating LookAt position from rotation and translation matrix

I was wondering if it was possible to calculate a lookat position from the translation and rotation matrices (aka the building blocks of my view matrix). I need the lookAt position to implement a ...
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Find coordinates in one space from another

I'm trying to determine what coordinates are in one space when given a point in another space. For example, I've got a Matrix4x4 that I can use to convert a point in unity's world space to a skewed ...
63 views

correct matrix to draw mesh as flat object

I need to draw a tilemap for a 2d game. For that I created vertices with their relative positions already hard baked. The coordinates start top-left with (0f, 0f) and z is always 0. I rendered them to ...
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Removing duplicates/ignoring them from a 2 dimensional Array

I have a bool[,] Array for keeping track of Nations that are either at war(true) or neutral(false). The problem Im having is that when going over the matrix, to display al wars in UI elements, it will ...
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Object stuck to screen no matter what eye position is used

I've run into an issue when trying to write a simple rendering program in D3D11. I'm 90% sure it's to do with some faulty matrix multiplication or generation, but I've tried debugging the values of ...
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How to convert a 4x4 matrix transformation to another coordinate system?

Is there a general method to convert a matrix transformation from one coordinate system to another, so that the resulting transformation looks the same on screen? For example: There are some ...
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Setting glOrtho and glViewport so top-left of window has coordinates (0,0)

I haven't used OpenGL for a long time and have trouble setting up a 2D screen where the upper left window coordinates are (0,0) and the width and height of the ...
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Transforming 3d point for depth testing

I have a ray and its direction is (o,d). Multiply it by the model matrix to rotate the model. ...
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How does this 4 by 4 matrix (about 4 points are coplanar) come up with this equation?

I have just begun learning some 3d mathematics and OpenGL (trying to implement skeleton animation). I am stuck here when reading a book(Advanced Methods in Computer Graphics). I understand the first ...
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Efficient calculation of billboard sprite transformations

I'm currently adding a billboard mode to animated sprites and static sprites in my 3D engine. The code below works fine, but I want to know if a more optimized solution exists. I've heard about ...
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How to convert a list into coordinates in pygame

I'd like to have a map in my pygame game but don't want to waste time moving each individual object in it. To resolve this, I'd like to iterate over a list like this: [1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ...
1 vote
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Calculating bone transformation matrix for vertex skinning

I have an issue with calculating transformation matrices for animation mesh deformation using glm in c++ I have a class Bone which does the basic calculation which does have a current local position (...
1 vote
240 views

Understanding matrix transformations for skeletal animation

I am working with Collada and GLTF. Say I have a humanoid with 3 bones with the following hierarchy: B0(root) → B1 → B2. Terminology: bind pose is the same thing ...
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Apply a mocap to multiple different models? -> modify gltf directly?

I am currently struggling with an animation I made that I would like applied to multiple models, all different, but from the same vertices. I already have a custom gltf importer ready but I need to ...
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Why would some assets require a transposed TBN matrix?

I'm writing an OpenGL/DX11 Windows/Linux "engine" and I've encountered a confusing behavior in DX, specifically. For math, I'm using GLM, which means all of my HLSL ...
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Matrix math: How to specify camera distance so that an object with a given size is completely visible?

This is my code that draws a top down view tile based map. But Iam do not know how high the camera needs to be placed in the sky so that the map is fully visible so that nothing is cut away and I do ...
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How to calculate camera view matrix from world transform, specifically the orientation?

In my engine, camera is just any other object in the scene. It has a transform -- position, rotation (quaternion), and scale (ignored for camera view matrix). I want to convert this to the camera's ...
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Find out (general) orientation of cube faces with rotated and translated camera

I have the following problem. I have a camera that is initially looking at a cube. The cube is with center at (0, 0, 0). The camera that is initially on (0, 0, 60). The camera can rotate and translate ...
1 vote
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Speed up Reaction-Diffusion simulation calculations in Unity

I'm trying to use Unity Job system to speed up some calculation related to Reaction-Diffusion simulation. The calculations requires 2 matrixes, current and ...
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How are transformation matrices usually represented?

I know the bare minimum to do matrix multiplication and have implemented them from scratch a few times for various purposes, but every time I do, I make sure to be very clear to myself about where are ...
632 views

How to decompose a GLSL mat4 to original RTS values within vertex shader?

I need to get the rotation differences between the model and the camera. convert the values to radians/degrees and pass it to the fragment shader. for that I need to decompose and the Model rotation ...
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1 vote
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What is the correct way to combine transforms together?

I have a type called transform in my game engine: ...
1 vote
300 views

How to define custom coordinate space?

I'm trying to build small UI framework. And I want it to have a coordinate space such that origin is placed in top left corner (x increases to right, y increases to down). I think for UI it should be ...
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1 vote