Questions tagged [projections]
Questions about the conversions of a 3D model to a 2D model.
135
questions
5
votes
1
answer
230
views
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
5
votes
2
answers
228
views
How to get the transform amount from a screen vector and a direction vector?
I am working on the move tool in a 3D modeling software. I need to know how much to move when the user drags an axis of the gizmo (for example along the x axis).
I have the 2D vector describing how ...
- 377
5
votes
1
answer
844
views
Do straight lines always remain straight when projected with a perspective camera?
If I have a straight line in 3D space and I use a camera matrix to do a perspective projection into a 2D plane/screen will the resulting line always be straight too? If I project the start point and ...
- 53
5
votes
1
answer
240
views
Am I calculating perspective projection correctly?
If I have a point in world space: (wx, wy, wz)
and I have a centre of projection: (cx, cy, cz)
and I wanted to project that point using perspective projection
would my point on the screen be ...
- 317
5
votes
1
answer
164
views
Where should I project a polygon corner when it is behind me?
I am creating a simple 3D engine as a learning project to get the hang on spherical trigonometry. I am using the following approach.
1. A model consists of a lot of triangular faces.
2. Each triangle ...
5
votes
1
answer
167
views
Project quad onto ellipse in 3D
I have three points P0, P1, P2, which are located on an arbitrarily oriented ellipse in 3D space. I have a square texture map with a circle on it. I would like to render a textured quad (with the ...
- 151
4
votes
1
answer
270
views
Projected points and screen coordinates
I'm trying to understand part of the contents of a slide, but I'm not really understanding. So, here's the interested part.
I've a few questions.
Are the projected points $q_1$ and $q_2$ the points ...
user4718
4
votes
1
answer
2k
views
Perspective correct interpolation z-buffer
While I was deriving expressions for perspective-correct linear interpolation on triangles, I reached the conclusion that the interpolation may be kept linear only if view-space $Z$ is available. ...
- 2,226
4
votes
1
answer
313
views
Creating Sparks using Code
I'm new to this area and have less knowledge. I want to create some graphics like sparks and lightning by writing some code, using my own physics. I don't want to use some engine, However I can use ...
- 41
4
votes
2
answers
110
views
2D projection from some points
I am going through an undocumented function that takes in three points and a Z-value that projects three points on the plane defined by Z-value. I want to understand the mathematical theory behind it ...
- 1,279
4
votes
1
answer
1k
views
How to use GetViewProjMatrix().TransformVector(LineDirection) in UE4?
I try to project a 3D vector (a direction, not a position) in screen space, but it does not return satisfying results:
...
- 377
4
votes
1
answer
8k
views
understanding glm::perspective vs glm::ortho
I'm new to computer graphics. I played around with OpenGL and now am trying out Vulkan.
Basically what I want to do, in 2D is have an 800x800 window, and I want that to represent 800 meters by 800 ...
- 269
4
votes
1
answer
1k
views
How to derive Field of View (FOV) angles from a 2D projection
I'm looking for some guidance.
I'm not sure if this is possible, and I'm not sure where to start.
I need to measure the FOV angles of a first-person, 3D game using only gameplay screenshots.
I'm bound ...
- 51
4
votes
0
answers
177
views
Project grid on 2d plane based on camera perspective
Unsure if this is the right network to post this, but maybe someone can help...
I'm working on a personal project where, with the help of AI, I want to automatically estimate the perspective of a ...
- 41
3
votes
2
answers
277
views
$(x, y, 1)$ is 2D homogenous coordinates or 3D homogenous coordinates?
We know that $(x, y, 1)$ are the homogenous coordinates of a 2D point $(x, y)$. $(x, y, 1)$ has 2 degrees of freedom. That's why we should call it 2D homogenous coordinates. But many websites say it's ...
- 211