Questions tagged [matrix]
91 questions
8
votes
4 answers
Why does opengl use 4d matrices for everything?
What I managed to figure out is that the first 3*3 is used for rotation and scale and the 1*3 at the end is used for position, but what is the bottom row used for?
is it only for clipping related things?
Yoris
- 81
- 3
6
votes
2 answers
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 "space"? Is it every point on my object? If so, the…
S.A
- 317
- 3
- 14
6
votes
1 answer
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 section on matrices, it describes 2x2, 3x3, and 4x4…
johnmarinelli
- 163
- 5
5
votes
2 answers
row and column majored rotation matrix pre- or post- multiplied
For column-major rotation matrices (right up forward in columns) do you right-multiply (post-multiply?) a row vector or left-multiply (pre-multiply) a column vector to result in a correct/valid transformation? Or are both "valid" but just transform…
Matthew L
- 53
- 4
4
votes
0 answers
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 points to a right-handed (UVN) viewing space, so…
TheRapture87
- 181
- 2
2
votes
2 answers
Screen space coordinates to Eye space conversion
I'm trying to figure out how to reverse Eye space -> projection -> clip(divide by w) -> screen space conversion.
Basically, I want to get Screen space (still have z value for z-buffer) -> undivide? by w -> inverse projection.
I found the inverse…
hans-1795
- 33
- 1
- 4
0
votes
0 answers
Compose ViewMatrix and ProjectionMatrix
As the title says, you are able to compose the ViewMatrix and the ProjectionMatrix into one instead of multiplying a vector by the individual matrices.
Instead of doing this at run time for each item:
Vector * ViewMatrix -> Vector…
Nixcc
- 33
- 7
0
votes
1 answer
Why do we call it TRS and MVP, instead of SRT and MVP or TRS and PVM?
Here's something that's been bothering me while learning graphics. We have two core concatenated matrix sets: "TRS" for transforms, and "MVP" for moving everything into the canonical view volume.
TRS is applied in this manner: T(R(S(p))), i.e. the…
Thomas
- 1
- 2
0
votes
0 answers
Write down the window to viewport transformation matrix if the viewport PQRS is normalize in the range of [-1,1]
What exactly will be the final matrix?
"Consider a window ABCD whose lower left corner is A (XWL,YWL) and the upper
right corner C is (XWm, YWM). A viewport PQRS has been defined with the lower
1eft corner is P (XVL , YVL ) , and the upper right…
