All Questions
Tagged with projections opengl
15
questions
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36
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How are these two projection matrices related?
I have two 3D perspective projection matrices $A,B$ with standard projection parameters $k=\cot(\theta/2)$, where $\theta$ is the field of view, $n$ is the $z$-near value, $f$ is the $z$-far value, ...
- 157
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In perspective projection matrices, why isn't $z_\text{eye}$ mapped linearly to NDC?
As far as my understanding goes, in projection matrices $x_\text{eye}$ and $y_\text{eye}$ are mapped linearly to NDC by first using proportions to find $x_n = \frac{n\cdot x_e}{-z_e}$ and $y_n = \frac{...
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My projection matrix for OpenGL fails on non-symmetric boundaries
Assuming my viewing volume has x coordinates varies from l to r, and y varies from top to bottom, and finally z-axis varies n to f, I derived the following projection matrix:
...
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Understanding orthographic projection matrix clip coordinates
I'm confused about what orthographic projection matrix outputs. Based on what I know so far, orthographic projection matrix converts vertexes in eye coordinates into clip coordinates. But what exactly ...
- 167
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621
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how to change the near clipping plane of a perspective projection matrix for OpenGL
I am trying to only change the near clipping plane of a given perspective projection matrix for OpenGL.
My problem is, that the near clipping plane is way too close, and the far clipping plane is very ...
- 1,297
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is focal length equal to the distance from the optical center to the near clipping plane- openGL
The part confusing about opengl during studying the projection was that the focal length, top, left, bottom, right, wasn't declared, and it magically did it with FOV and image aspect ration. I ...
- 117
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769
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How are textures projected onto 3d models in texture painting applications
In most modeling software you can texture paint onto 3d models using so called stencil textures. They basically project a texture from the viewport view onto the model as seen for instance in the ...
- 516
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How to unproject cursor with orthographic projection
With perspective projection we can unproject screen space coordinates of the cursor to the near and far plane of the frustum and calculate the direction of the ray through the cursor.
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- 516
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120
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Keep constant number of visible circles in 3D animation
I have created a 3D animation with a perspective projection of white circles moving randomly in a fake 3D space projected on a 2D computer screen (GIF 1).
Since I need to keep the same number of ...
- 113
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67
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How combine multiple projections into a single pass?
We have a projector type display used in an automotive application, where a projector displays an application on the windshield. Because the projector would normally warp a flat image, we have to ...
- 333
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277
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What quad will fill the screen, which can be inverse-projection-view transformed to map to the near frustum plane?
I've been experimenting with raytracing using GLSL. I had success rendering a cube which encloses the object.
Now I want to do a full-screen raytrace, and I want to construct a quad which covers the ...
- 299
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Project vertex onto plane
What I have:
a plane given by its normal$\ n $ and a point on the plane$\ p $.
a 3D-point$\ v $.
a direction$\ d$.
What I need:
the projection of$\ v$ along$\ d$ onto the plane.
How can I ...
- 23
2
votes
1
answer
155
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A way to save 360° panorama video
What is the best way to save video from faces of a cube? The render can produce 6 squares (90°x90°) of 1024x1024 resolution. Faces oriented along axies and only position is changed continuously. I ...
- 241
7
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1
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Zoom in orthographic vs perspective projection
I have read through this article about perspective and orthographic projection matrices.
I started playing with the perspective matrix and as expected if I either increase/decrease the field of view ...
- 969
9
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2
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904
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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 (...
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