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.

75 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
9
votes
1answer
110 views

How to clip cut-off using different frustrum than that of original camera? How to cut plane by pyramid shape?

SOURCE : http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2012/10/Mitchell_LightShafts.pdf This process is part of creating light draft effect. And I am suggested to do the described process in ...
4
votes
1answer
110 views

Optimizing black and white matrix block drawing

Disclaimer: I am uncertain if this is the best place to post this question, so please advise me of how I can best find the answer if I am doing something wrong. I am asking this question because I am ...
3
votes
1answer
50 views

Matrix math in cascade shadow mapping

I am implementing cascade shadow mapping algorithm and currently stuck with matrix transformations - my AABBs, when projected in light space are pointing in the direction opposite to the light: I was ...
3
votes
0answers
190 views

How to convert screen to world coordinates while using gluLookAt / gluPerspective or similar matrix transforms?

I am just starting an adventure in looking under the hood of graphics for a game project I've been working on for a while, and I could use some guidance. I am using Python/Kivy (though that is not ...
3
votes
0answers
503 views

Control frustum near and far clip plane sizes in a Projection Matrix

I'm trying to achieve a dolly zoom effect. My first try was the obvious one, the original "zoom in & dolly out" technique, which works nicely. Except that there are cases which this is not ...
2
votes
0answers
38 views

How to apply a color transform to textures when using pre-multiplied alpha?

I'm trying to apply a color map to my textures. The map is a 4x4 matrix that adjusts the contribution of each RGBA channel returned from the fragment shader. My texture needs to use pre-multiplied ...
2
votes
0answers
185 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? ...
1
vote
0answers
37 views

Matrix transforming with translation/rotation/scale at center of screen

I'm trying to create a camera using matrix transforms, the gist is as follows: ...
1
vote
0answers
21 views

Recognize L-Shape in a 4x4 Matrix

I'm trying to make a board game, there the player has to press four buttons to make the L. It can be mirrored or rotated, it just has to be an L. But if the player press four buttons and make another ...
1
vote
0answers
52 views

Can't get world position from reverse Z buffer

I'm using this solution to render using a reversed Z buffer. This looks fine and completely fixes all my z-fighting, but it breaks what I use in shader to derive the world position from the depth for ...
1
vote
0answers
48 views

Why does the Modelview Matrix in OpenGL not have accurately signed vector values for look vectors?

When I do a GluLookAt(0.0, 500.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, -1.0) so that I'm 500 units up on the positive Y axis looking down at the origin with the top vector of the camera pointing toward the ...
1
vote
0answers
31 views

My triangle disappears when multiplaying by my perspective projection matrix

Whenever I multiply my transformation matrix, which is passed to the shader via constant buffer, my triangle disappears. Here is the code for the passed matrix: ...
1
vote
0answers
125 views

How to calculate rotations for an object with scaling transformations?

I am working on implementing scaling transformations into a game engine (C++), which previously assumed only translations and rotations. Visually, the scaling works, but a lot of the game logic ...
1
vote
1answer
201 views

What should the Z coordinate be after transformed by the projection matrix?

I'm working on an OpenGL 1.x implementation for the Sega Dreamcast. Because the Dreamcast didn't have any hardware T&L the entire vertex transformation pipeline has to be done in software. What ...
1
vote
0answers
52 views

Matrix for transforming a square to a quadrilateral

I have a square of points {<0, 0, 0>, <6, 0, 0>, <6,0, 6>, <0,0,6>} (The square is placed at the origin in the xz plane in opengl). Want to apply a transformation/s on the square and make ...
1
vote
0answers
117 views

Convert bones by bone matrix

I have a 3d-models from old game. They have the following structure: ...
1
vote
0answers
51 views

Blender - Exporting and Replicating Bone Animation

I'm having trouble replicating Blender bone animation in my game. Bones that have a vertical rest position (Euler(PI / 2, 0, 0)) are animated correctly (e.g. head, neck, torso, legs, shins), however ...
1
vote
0answers
47 views

Does it make sense for a view matrix to have a scale?

When building a view matrix from an SRT matrix multiply, examples (here and here) only ever compose it with a R and T. Does it make sense to have the S component be anything other than the identity? ...
1
vote
0answers
135 views

OpenAL listener position for isometric camera

I have an isometric camera for an RTS that looks like this: Basically, I don't know how to set the listener's position in OpenAL because I represent the camera's position with only two coordinates. ...
1
vote
0answers
493 views

Setting relative anchor point via matrix

The page at https://webglfundamentals.org/webgl/lessons/webgl-2d-matrices.html provides an example for rotating around the center of the image: ...
1
vote
0answers
710 views

SceneKit-Convert a rotation vector into rotation matrix

I'm very new and I'm studying this ARKit code from RPasecky/CubesInSpace on github where he/she convert the point of view 's rotation vector into a rotation matrix ...
1
vote
0answers
84 views

Cube Translation Looks All Wrong

I'm making a very simple cube in OpenTK and it seemed to be going fine until I tried to move it around. Moving it along the X Axis seems to elongate the cube, not the result I hoped for. My Vertex ...
1
vote
0answers
198 views

Understanding the ModelView Matrix

I want to analyze the each component of my 4*4 ModelView Matrix. I came to know that the starting 3*3 of ModelView Matrix ...
1
vote
0answers
144 views

Rotating an Object Around an Axis

I have a circular shape object, which I want to rotate like a fan along it's own axis. I can change the rotation in any direction i.e. dx, dy, dz using my transformation matrix. The following it's ...
1
vote
0answers
968 views

how to properly rotate in directX11

I am trying to Rotate a textured quad in directX however I think i am missing something. I am pretty sure it is because i am applying transformations to the WorldMatrix instead of the ObjectWorld, ...
1
vote
1answer
369 views

How to apply bindpose for vertex skinning?

I'm creating a model/animation viewer in C# using OpenTK for a game's models. Before stating my problem I want to describe a bit what I've accomplished so far in case I'm fundamentally missing ...
1
vote
0answers
2k views

Matrix transform from one coordinate system to another

I have been beating my head against the wall for weeks on this and it is time I just break down and ask for help. I need to move a 3D camera from an in house system into Unreal 4. The two use ...
1
vote
0answers
144 views

Is it normal in skeletal animation to NOT consider the translation component in bone transform matrices?

I'm using assimp to load a model, and DirectX11 and DirectX ToolKit to render it. In the document of DirectXTK's IEffectSkinning, it says: As an optimization, SkinnedEffect and DGSLEffect assume ...
1
vote
0answers
40 views

Connecting a model's joint to the joint of another model

I am trying to figure out the math behind orientating and translating a model so that a specified point on the model will connect with a specified point on another model. For example, given the ...
1
vote
0answers
99 views

Relative Transformations for Bones

I'm using Blender to export my armatures in relative coordinates, and I'm trying to get to absolute coordinates in my engine. For the above example, the childBone's ...
1
vote
0answers
377 views

How should matrix-based Parallax Scrolling work?

The question is at the end, as it requires a bit of context. I'm not sure if my understanding, my code, or LibGDX's ParallaxCamera is wrong. LibGDX's ...
1
vote
0answers
198 views

Rotate view matrix based on touch coordinates

I'm working on an Android game where I need to rotate the camera around the origin based on the user dragging their finger. My view matrix has initial position of sitting on the negative z and facing ...
1
vote
0answers
138 views

Rotate Points with Object in world space

I posted this in the original stack overflow then realized that a game-dev specific one exists. I am working on personal project that requires me to have 4 points surrounding an object (1 at each of ...
1
vote
0answers
826 views

Stacking Drawing Matrix for SpriteBatch in XNA

I'm trying to make a 2D engine for XNA with SpriteBatch. My object unit is Entity, which can include other ...
1
vote
0answers
214 views

How do I implement a physics gun?

I'm currently trying to implement a physics gun for my game. What I want is for the entity to stay in the same position on the screen no matter how I wiggle the camera about, what is the correct way ...
1
vote
0answers
823 views

Drawing two orthogonal strings in 3d space in Android Canvas?

I want to draw two strings in canvas. The first string must be rotated around the Y axis, for example 45 degrees. The second string must start at the end of the first string and also it must be ...
1
vote
0answers
441 views

Matrix.CreateBillboard centre rotation problem

I'm having an issue with Matrix.CreateBillboard and a textured Quad where the center axis seems to be positioned incorrectly to ...
1
vote
0answers
330 views

How do I convert my matrix from OpenGL to Marmalade?

I am using a third party rendering API, Marmalade, on top of OpenGL code and I cannot get my matrices correct. One of the API's authors states this: We're right handed by default, and we treat y as ...
1
vote
0answers
556 views

Getting and Setting Rotation in XNA around the Center of my Model with XNA

Alright, so I'm currently debating how I want to do this. Basically this is what I'm trying to accomplish. I've created a system to allow me to make my environment a little bit easier. I'm ...
1
vote
1answer
786 views

Getting world coordinates from mouse position

I am drawing a 2D mesh imported from CAD. The mesh vertex coordinates are in feet from some arbitrary origin and Z is always 0. I am supplying the coordinates to my shader program and using projection ...
0
votes
0answers
24 views

2d zooming function using transformation matrix

I'm trying to create a sort of "graphing calculator coordinate system" where you can zoom into a point by scrolling with the mouse wheel. I'm using javafx's transformation matrices (Affines) ...
0
votes
0answers
25 views

Obj file vertex coordinates to new coordinate space

I am trying to convert the vertex positions in my obj file to a new coordinate system. I understand I need to multiply each vertex with the transformation matrix, however I am trying to figure out the ...
0
votes
0answers
23 views

3D to 2D transformations with numpy

I am trying to create my own game in the python terminal, but I just can't find something I can use in python. I found something on https://www.gamedev.net/forums/topic/59091-projection-matrix-amp-3d-...
0
votes
1answer
56 views

Need help getting an objects orientation / all my OpenGL rotations are reversed

I'm using OpenGL on Ubuntu Linux with the Eclipse IDE and the GCC compiler. I am bringing blender models into a homemade renderer/game engine. I parse a text file containing object descriptions to ...
0
votes
1answer
49 views

convert world to screen coordinates with camera position and camera angle

Heyho :) I'm trying to convert world coordinates to screen coordinates. I have available: fov, screen width, screen height, camera position, camera angle and obviously the position of the object in ...
0
votes
1answer
59 views

Cylindrical billboarding around an arbitrary axis in geometry shader

I found an answer on this site relating to this question already, but it doesn't seem applicable in the context of my project. Basically I'd like to create a method which fits this signature: ...
0
votes
0answers
77 views

Shifting the world origin and scaling all points?

Imagine you have a simulation in very large coordinates, and to render it out you need to scale it down (say, solar system -> fitting inside a few thousand units). This is controlled by a float ...
0
votes
0answers
24 views

Rotate & Translate a MatrixTRS

Hello I have a question about translation & rotation of a MatrixTRS... So basicly I have a given MatrixTRS A in space, define by a positionA, rotationA and scaleA. (DISCLAIMER: I am using Unity, ...
0
votes
0answers
29 views

What is an efficient way to get a look-at direction from either a quaternion or a transformation matrix?

So, I have an object in my custom engine (C++), with a column-major transform in world space. I'm using a package that takes a look-at direction as an input. What's the most efficient way to get a ...
0
votes
0answers
38 views

How can I transform a 3D triangle to be coplanar with another congruent triangle? - How can I superimpose two congruent triangles?

I need to transform an equilateral triangle that is lying flat on the xz plane, to become coplanar with another congruent equilateral triangle. I am developing a simple low-poly space exploration game,...