Most Popular
1500 questions
4
votes
1 answer
Special Texture Stretching without deformation
I am trying to achieve a special texture stretching effect in my shader.
Here is how I define my uv before sampling my texture, nothing really special.
// uv_ST contains the tiling and offset values
uv.xy = uv.xy * uv_ST.xy + uv_ST.zw
This gives…
MaT
- 1,229
- 10
- 21
4
votes
1 answer
Irradiance Map Equation What is "dω"?
Link to paper : Irradiance and Incoming Radiance | lawrence.edu
Using a shader to compute En
Computing En as described above is a very compute intensive operation,
because we have to compute the integral over the cube map for each new
…
Blue Bug
- 321
- 2
- 7
4
votes
4 answers
How to build a 3d model from 2d pictures
I have a series of MRI images. I want to build a 3D model out of it, which not only presents the surface, but also contains the inside structures. What kind of photogrammetry based method can realize that?
Milo Lu
- 141
- 4
4
votes
1 answer
Efficiently sampling specific surfaces using MIS in path tracing
Apologies for posting two questions in one post, but as they are relevant I kept them in one.
Question 1
In the definition of multi sample estimator that Veach has defined, the integrand is the same for all the n sampling strategies. If this is so,…
ali
- 740
- 4
- 14
4
votes
3 answers
What's the concept of "Ray" really?
I'm learning Ray Tracing using this MIT tutorial.
I've heard Ray Tracing only in the context of lighting. I.e. I understand that ray casting is used to light an object that has been already drawn. However, I've also seen ray casting in the context…
mavavilj
- 251
- 1
- 5
4
votes
2 answers
reducing image size increases file size?
When I download this image:
(source: ucn.edu.ni)
then its total size is 341,0 kB.
The image has a width of 2880 pixels and height of 1100 pixel and 1 X/Y resolution pixel/in.
I opened the image with gimp and pressed scale image and reduced the…
Adam
- 143
- 5
4
votes
1 answer
Stretch the cube mesh but repeat the texture?
I have a simple cube mesh, which I scale with modifying the model matrix.
Texture settings:
glGenTextures(1, &m_texture);
glBindTexture(GL_TEXTURE_2D, m_texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S,…
Tudvari
- 313
- 1
- 3
- 13
4
votes
1 answer
Calculate Transformation between two point sets - but with constrained Degrees of Freedom
How can I calculate the rigid transformation [R|t] between two 3d triangles, but restricted to a given N degrees of freedom (for N = 1..6) ?
I know for N=6 I can get a least-squares solution via SVD of a certain matrix, but how can I integrate…
ginsunuva
- 123
- 3
4
votes
1 answer
Alpha blending between two overlapping semi-transparent shapes
I am working on a 2D lighting system for my game. My approach has been to:
Create a transparency quad representing 'darkness'.
Create a stencil shader for light sources to clip from the darkness quad.
Create a shader that blends alpha from 0 ->…
Alex
- 141
- 1
- 3
4
votes
1 answer
What happened to my texture mapping?
Recently, I am writing a simple software rasterizer for self-studying and fun. But the texture mapping has problems. The texture I want to map is below:
But the final image of two triangles is problematic, it shows below:
The triangle rasterizing…
alexunder
- 141
- 2
4
votes
1 answer
Energy conservation of BRDF
I'm reading Advanced Global Illumination.
Here is the part confusing me:
What do the second equation and $\delta$-function mean?
Why the third equation is a sufficient condition even though a reason is given?
chaosink
- 591
- 1
- 4
- 15
4
votes
2 answers
Can a scene graph be stored in the GPU?
I am starting to learn WebGL. Can a scene graph be stored in the GPU? Or is that type of thing more for the main thread (or webworker)?
For example, I want to calculate some layout, and apply it as a transform matrix. Can I keep track of a scene…
trusktr
- 255
- 1
- 6
4
votes
1 answer
Main techniques to draw a point at non integer coordinates?
I've difficulties in looking for an answer by myself because I don't know the jargon. I need somebody who'll points me in the right direction.
Assume I have 100000 points with coordinates in the unit square, so points like (0.55313, 0.236831).
I…
Giovanni Resta
- 143
- 3
4
votes
1 answer
Z buffer working in OpenGL
After Z-Buffer Testing does the fragment shader run on the discarded fragments?
Does the Z-Test happen after the fragment shader runs?
Please, tell me the step by step events that occur in the Z-Test.
Also what is early Z-Test and how to achieve it?
VersesDev
- 129
- 5
4
votes
1 answer
Algorithm to map a triangular mesh onto plane preserving angles and distances from one vertex
I have a 3D triangular mesh representing cortical surface of a brain. I also have one vertex of interest. I would like to unfold a neighborhood of this vertex in such a way that both the angles (their ratios) and distances of paths from this vertex…
Evgenii
- 159
- 3