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1500 questions
5
votes
2 answers
Multiple Importance Sampling in Path tracer produces Dark Images
So I recently implemented Multiple Importance Sampling in my path tracer which was based on next event estimation.
The problem is without MIS I get images like,
This is obtained by setting
light_sample *= 1/light_pdf; // Note no mis_weight
and…
gallickgunner
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5
votes
1 answer
What algorithm to reassemble a broken image?
What algorithm can I use to reassemble a broken image?
Is there any technique? algorithm? Can I use graphs? machine learning? computer graphics?
information
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5
votes
1 answer
Do operating programs such as Microsoft Office or Windows Explorer use OpenGL to draw?
I have a server and my only monitor is plugged into its graphics card.
My question is - do all programs (Windows explorer, Excel whatever) draw their output using the graphics card and more specifically an API such as OpenGL?
The output is coming…
Startec
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5
votes
2 answers
What's the point of "work groups" for OpenGL compute shaders?
glDispatchCompute has the number of work groups as arguments.
What is the point of having work groups? How are they useful, compared to just having NxM independent pixel calculations with a known (x,y) input parameter in the shader?
spraff
- 289
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5
votes
2 answers
Can i compile my shaders to SPIR-V without using glslangValidator?
I'm making a cross-platform application, and i need my shaders to be compiled to SPIR-V for both Opengl and Vulkan. It seems that the only way to do so is to call a separate program, called "glslangValidator.exe/.deb/.dmg". This sort of makes it…
user9436
5
votes
1 answer
How to compute normal of surface from implicit equation for ray-marching?
I want to represent ovaloids with ray-marching. I have ovaloids defined with an implicit equation.
For instance, we can consider the equation of an ellipsoid given as: $$ \frac{x^2}{a^2} + \frac{y^2}{b^2} + \frac{z^2}{c^2} -1 = 0, $$ where $a, b,…
EvaMGG
- 153
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5
votes
2 answers
Generate mesh from pointcloud data
Given point-cloud data :
For example.
position + color and normal.
What will you use to generate mesh of this data
and keep reasonable quality for real time cases ?
Additional info to consider:
In some cases given also
3D cameras world…
barakooda
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5
votes
1 answer
Problems rendering a plane via `drawElements`
I am generating plane vertices where the y values are generated by a heightmap (noise) algorithm. This is how I produce my vertex array:
for (let row = 0; row < noise.length; row++) {
for (let col = 0; col < noise[0].length; col++) {
…
チーズパン
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5
votes
2 answers
Refraction: given an incoming and transmitted direction, can I deduce the normal?
It's easy to find guides to calculating the transmitted direction of light given an incoming direction, the normal, and indexes of refraction. However, I can't find anything about determining the normal, given all the other information. That's…
Phil McLaughlin
- 88
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5
votes
1 answer
Grainy image in my simple ray tracer
The wall on the left of the red ball is perfectly reflective wall.
In the first image there's a point light that lies on the plane of the reflective wall and in the second image, it's 0.01 units ahead of it. Due to the light being on the…
Newbie
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5
votes
1 answer
What part of the graphics chain rotates computer displays when in portrait mode?
When the display hardware is physically rotated 90 degrees, your graphics can still be rendered with the correct side up. Where is this rotation accomplished?
I can imagine a few possibilities:
A) The code for every low-level graphics primitive…
Joakim Rosqvist
- 153
- 2
5
votes
1 answer
Manually fetching 8 neighboring texels from 3D texture greatly decreases performance
I'm implementing manual interpolation between texels in a 3D texture to be able to discard some of them when needed. Compared to hardware interpolation, this process takes a lot of time. If I simply leverage hardware interpolation using texture…
Pavlo Muratov
- 243
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5
votes
1 answer
Phong and the Rendering Equation: What's with the cosine?
Ignoring emission and shadowing for simplicity, the rendering equation can be stripped down to:
$$L(x, \, \vec \omega) = \int_{\Omega}{f_r(x, \, \vec \omega^\prime, \, \vec \omega) \, (\vec \omega^\prime \cdot \vec n) \, d\vec \omega^\prime}$$
where…
David Kuri
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5
votes
1 answer
BRDF normalization
I don't understand how to normalize the BRDF.
the constraint is that for each incoming ray, the exitant ray will be $1$ at most
ie integral of hemisphere of $f_r\cdot\cos(\theta)$ where $f_r$ is the BRDF and $\theta$
is the elevation angle.
the…
kalonymus
- 53
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5
votes
1 answer
Precision problem on AMD
I have a problem with precision on AMD in shaders (hlsl). In vertex shader I calculate UVs for particle using modulus operator on float. With simple % there is a problem on Nvidia and on AMD (e.g. 7 % 7 = 7) so I have written modulus as:
float Mod(…
Derag
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