# Questions tagged [matrix]

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### Building view transform matrices

For a 3D scene in the world coordinates, its View Reference Point $\mathrm{VRP}$ is at $(5,-2,1)$, and a viewer is looking towards point $A=(1,1,1)$. Construct a transform matrix which will map world ...
• 307
1 vote
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### Scalar multiplication in vecmath on Matrix4f results in strange values

So I have a matrix: ...
• 251
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### Correcting my "look-at" matrix so that it works on non-camera objects?

I'm familiar with the "look-at" matrix and the goal of being able to rotate a Camera at a specific location towards a specified target. When I tell the ...
• 166
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### Unable to pass custom Matrix4 to GLSL as a uniform

I am fairly new to graphics programming and I am trying to pass a custom Matrix4 (non-glm) to my vertex shader by using a uniform. ...
• 33
998 views

### What's a parent vector space or coordinate system?

After asking this question, a few new terms that I had never heard of came up. Note, I'm quite familiar with linear algebra, but I've never heard these terms in the context of linear algebra. ... 2k views

### How is that possible that matrices can be thought as coordinate systems?

I've been reading around that matrices (for example, rotation matrices, but not only) can be thought somehow as coordinate systems. My question is: how is that possible? I've seen for example that ... 286 views

### Detect a lossy matrix decomposition?

I am writing a plugin to export data from 3DS Max. 3DS Max's geometry pipeline is... interesting. As part of my plugin I decompose a transform matrix into a translation, (quaternion) rotation & ...
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### How to translate object to origin?

I want to rotate a 3D object. On this website http://paulbourke.net/geometry/rotate/ the first step says: (1) translate space so that the rotation axis passes through the origin What is meant by "...
• 307
143 views

### Ladder to DNA using Transformation Matrix

In my last Graphic mid-term, the exam contained a Transformation Matrices problem, its statement was: Question Rotate the following ladder to form a DNA-shaped ladder using a transformation matrix....
147 views

### Correctness of logical steps for create the matrix of viewing transformation

In general, I understand the creation of viewing transformation matrix, but I have my doubts. For example, let's say that a world coordinate (called $A$) has a center at $(1,1,1)$, and the view ...
• 321
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### Solving a problem from *Foundations of Computer Graphics*:

From Gortler's Foundations of Computer Graphics (i.e., self-study): Let $\mathbf{\vec{e}}^t = \mathbf{\vec{w}}^t E$ and let $P$ be a camera matrix that is just some arbitrary $4$ by $4$ matrix with ...
• 253
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### 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 ...
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792 views

### Do we use 3x3 matrices in computer graphics?

I've been doing some side-research on computer graphics as a hobby and came across this article on quaternions: http://www.opengl-tutorial.org/assets/faq_quaternions/index.html#Q2 In the first ...
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### Animating a smooth linear transformation

After watching this video on matrices, I tried to make a simple animation of 2D linear transformations. Starting with a set of 2D points in a grid, I applied a 2x2 matrix to each point and obtained a ...
• 287
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### How to unproject quadrilateral into rectangle?

tl;dr: Math problem in projective geometry: How does one find some 4x4 camera matrix that gives a projection as illustrated below, such that points A,B,C,D are somewhere on the edges of the unit box (...
• 191
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### Confusion about notation in a paper

I have been trying to understand "Fast Simulation of Mass-Spring Systems" by Liu et al., which can be found here. There is one part in the methods section that is confusing me. Just after equation 12, ...
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### Object rotating around origin instead of object center?

I am implementing simple rotation but the object is not rotating around the local center instead it is rotating around world origin. This is the code: ... 272 views

### View Reference Coordinate System

For a 3D scene in the World Coordinates, its View Reference Point is at c=(0,3,4), and a viewer is looking towards its origin O (0,0,0). Construct a transform matrix which will map World Coordinate ...
• 171
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### 3D rotation matrix around vector

I am using matrix for performing 3D rotations. I know that in 3D space the matrix product order is important - changing the order of the matrices can effect the rotate result. So I am interesting ...
• 157
282 views

### Affine Transformation

We have a matrix $$\begin{bmatrix} a_{11} & a_{12} & a_{13} \\ a_{21} & a_{22} & a_{23} \\ a_{31} & a_{32} & a_{33} \end{bmatrix}$$ This matrix represents a ...
232 views

### Image based lighting, tangent space coordinates, and optimization

When I saw an implementation of normal mapping that computed the TBN matrix in the vertex shader and converted everything (in particular the view vector and light vector) to tangent space at that ...
• 4,260
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### Coordinate system transformation in motion capture files

I am trying to align two motion capture files from different sources. The motion capture file consist of a skeleton specified as a hierarchy of joints. Each joint i.e. "shoulder" has three pieces of ...
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### Choosing & Using a Projection Matrix

I'm looking into the graphics pipeline processes and at the moment in particular, perspective projection matrices. After looking in several different sources, and across the breadth of previous ...
• 203
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### Correct view-space transform

I am attempting to model a simple graphics pipeline (i.e. Local->Word->View->Screen->2D spaces). I've been looking at the algorithm required to transform from world to view-space and using the ...
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