Questions tagged [glsl]
GLSL is the OpenGL shading language. Use this tag for questions which are specifically about shaders written in this language. For generic shader questions use [shader] instead.
256
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GLSL, Fragment Shader: How to separate functions (like noise, transform...) to reuse in different projects
I'm a total newbie to coding and recently got interested into generative art.
This is my problem:
I have to copy all of the functions I need (and there are a lot) in every single fragment file I'm ...
2
votes
1
answer
104
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using parts of GL_TEXTURE_2D_ARRAY as GL_TEXTURE_CUBEMAP_ARRAY
I am using layered rendering for all my light sources to avoid rendering multiple times.
I have lightSourceCount many point lights and one sun, which is implemented ...
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1
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312
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How to deform an object in glsl? (processing)
I am a beginner in glsl and processing. I have a cube, can I know how to deform it using mathematical or progammatical functions?
...
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2
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1
answer
131
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enable / disable transform feedback within glsl for specific primitives
I am using the tessellation shader stage to increase the density of triangles close to camera.
Thereby when the camera is too close to a triangle, so that the maximum tessellation is not high enough, ...
- 1,136
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2
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2k
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Opengl GLSL binding locations confusion
The background of this question is that I am trying to write an automatic binding system, where for each uniform variable I want to declare in my GLSL code, I call a method ...
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78
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Precision problems when rendering whole planets
I'm trying to implement a camera, which is able to go very close to a planet/moon surface, without flickering surface.
The problem:
Right now the position of a planet / moon is saved at the center of ...
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1
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1
answer
221
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Convert image to CIE Lab using GLSL to change hue/chroma
It is possible to convert an image or other output to CIE Lab color model using GLSL? Does it require compute shaders or can be done using only vertex shaders?
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168
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Achieving bokeh blur with custom shapes
I have a 2D texture, without any depth maps, which I'd like to blur to achieve a bokeh effect. The catch, however, is that I want the effect to be custom bitmaps/shapes (e.g. a heart). Here's a part ...
- 101
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2
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244
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Ambient occlusion depth buffer normalization
Been trying to follow a shader from A Comparative Study of Screen-Space Ambient Occlusion Methods
http://frederikaalund.com/wp-content/uploads/2013/05/A-Comparative-Study-of-Screen-Space-Ambient-...
- 3
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2
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138
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Tiling in GLSL creates unwanted seams
I'm writing a shader that creates a grid with coloured tiles. The color is derived from a pixel at that location on a texture. But around the tiles I get these unwanted seams.
I can't seem to figure ...
- 103
2
votes
1
answer
357
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Having trouble implementing distance transform with jump flood
I'm attempting to use the jump flood algorithm to compute distance transforms of an arbitrary texture derived from a canvas2d context, roughly following the explanations detailed here/here.
In the ...
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52
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Obtaining sample position z value when using positions from depth buffer for SSAO
I was looking to implement SSAO; demonstrated on learnopeng (https://learnopengl.com/Advanced-Lighting/SSAO). While I have implemented the way they have done it i.e using a position texture for ...
2
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1
answer
196
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Is there a better, more elegant way of translating/rotating my camera in my 3d raymarched world or am I stuck with trigonometry?
What I am trying to achieve
So I'm a fractal enthusiast and decided to build a 2D/3D fractal generator in WebGL using raymarching, with Typescript as scripting language. I've been a C#/Typescript dev ...
0
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1
answer
2k
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How to render fog in OpenGL
I have a simple question just because I can’t find any good example in the internet. How to create fog without using particles? How to make for with different density on different locations and in ...
- 103
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1
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460
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Dynamic Loop Based on Uniform
My question is fairly simple but I guess it contains two questions, one is how to arrive at an answer (imagine a similar one and you want to deduce it using existing tools like a GLSL compiler or the ...
- 278
3
votes
1
answer
780
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Compute Shader shared average value
Short Question:
How can i integrate a buffer variable in a compute shader over each pixel i.e. how can i ensure memory coherence in such a case?
Long Question:
I've written a deferred renderer with ...
- 163
0
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2
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468
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glsl passing data array from vertex to tessellation control shader
I am trying to pass a vec3 array from vertex shader to tessellation shader.
passing just one value works fine, but how to pass an array?
Vertex shader
...
- 1,136
0
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1
answer
191
views
optional geometry shader
I am looking for an easy solution for passing information between shader stages when adding additional shader stages.
Right now I am using the "out" keyword to pass data from for example ...
- 1,136
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1
answer
738
views
Ray-Marching: Rendering a Voxel Grid with Proper Normals
Dear Computer Graphics SE,
I have a RAYMARCHING renderer, that looks up voxel data from a 3D texture. Each cell in the texture can be 0 or 1.
I have a very simple algorithm for calculating the signed ...
- 201
1
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0
answers
174
views
Binary image blob movement prediction with optical flow
I got stuck with a problem: I have two binary images A and B, which differ by a few seconds. There are Blobs in the images which move (imagine a binary image of a lava lamp). Now I calculate the ...
- 111
0
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1
answer
98
views
Level of detail passed from vertex shader to fragment shader
I am looking at a sample code from a respected source and the mipmap level-of-detail parameter (float) is passed to the vertex shader as a uniform which then passes to the fragment shader without ...
- 299
0
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1
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873
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gl_ClipDistance vs gl_CullDistance
Why are there very similar yet distinct arrays: gl_ClipDistance[] vs gl_CullDistance[]?
What would be some use cases where the ...
- 299
0
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1
answer
76
views
SSBO get block of data instead of iterating
I have a mesh, each face (triangle) of the mesh needs to read some information out of a SSBO object.
Is there a way to read out a block (lets say 100 floats) at once? Or do I need to iterate over the ...
- 1,136
0
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1
answer
94
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Scale Sampled Depth Value
I am currently porting the atmosphere algorithm used by the UE4 engine to my engine.
As the original algorithm from Bruneton is in Kilometers i had to adapt it to my engine which uses meters. ...
1
vote
2
answers
591
views
Is there an efficient way to achieve color blending in compute shaders?
What I want is a function like imageStore, but instead of replacing a value - applying a blend operation to it, e.g. addition. It is not possible to do something ...
- 137
1
vote
1
answer
67
views
Mat4 that is written to a storage buffer in a compute shader has an altered value when read back
I am attempting to use a compute shader to calculate joint transforms for animations.
I use a loop to calculate the global joint transforms from the local transforms. Relevant code below:
...
- 33
1
vote
1
answer
3k
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Understanding fragment shader coordinate system
I'm trying to create an infinitely panable grid using fragment shaders (C++/OpenGL/GLSL), and I'm having a bit of difficulty understanding the coordinate system.
This is my fragment shader code, ...
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1
vote
1
answer
485
views
Opengl : GLSL utility files
We can create header files in C/C++ which we can include in our project using #include directive but when I use this keyword in my shader it gives the error reserved keyword. If let's say I create an ...
- 169
1
vote
2
answers
724
views
Is there a way to compile part of a shader into a spirv?
I want to have separate files for common things for shaders precompiled into a spirv.
For example PBR, I've got these functions and implementations for them
...
5
votes
0
answers
779
views
How to implement PCSS correctly?
I'm trying to implement PCSS in OpenGL/GLSL, but I have problems understanding the details especially the conversions between the coordinate spaces. The existing implementations are so different from ...
- 151
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1
answer
1k
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GLSL Compute Shader Setting "shared" memory buffer size
Is it possible to set the size of the shared memory of a compute shader workgroup from the host code? There is a way to do this in CUDA and I am suspecting that, since there is an GLSL extension to ...
- 299
0
votes
1
answer
270
views
imageLoad() behavior for non-existent texel
Is there a way to influence the behavior of imageLoad() for accessing an image2D or uimage2D ...
- 299
0
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0
answers
116
views
Numerical error in GLSL vector reflection
If I reflect a vector over a mirror, I expect it to end up on the other side of the mirror, even if there's a bit of numerical error. More precisely, if I run the GLSL code
...
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3
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0
answers
554
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Comparing different sampling methods for GGX IBL
I have made a demo that shades a sphere with an environment map. I wanted to compare 3 different ways of sampling the environment.
Uniform sampling.
Importance sampling with the NDF as suggested in ...
- 127
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0
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303
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OpenGL: "invalid value" error after call to `glGetBufferSubData`
My first question in this community.
I have following code.The code is shortened for clarity, error checks skipped:
...
- 111
0
votes
1
answer
46
views
Equally distribution on triangle surfaces
I would like to implement a random placement for objects like trees stones etc. on a triangles surface.
The important part is to have an equally probability to place an object on this surface. That ...
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2
votes
0
answers
82
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Atmospheric scattering band/seperation artifact
I am currently experimenting with some atmospheric scattering in glsl in my OpenGL engine.
I am experiencing a strange phenomena where a strange band / separation artifact appears along the middle of ...
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0
answers
160
views
IBL looks too dark with uniform sampling
I'm making a program that illuminates a sphere using an environment map. For each fragment in the sphere, I compute a many random directions in the hemisphere along the surface normal (no importance ...
- 127
0
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2
answers
759
views
Using imageLoad/imageStore to perform atomic add
I have a rgba16f texture that I fill with values using nvidia GL_NV_shader_atomic_fp16_vector extension, which allows to perform ...
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1
answer
90
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Problem sampling uniformly envmap with GGX
I have made a program that samples uniformly an environment map and computes the lighting using the GGX BRDF.
I have made a small example that reproduces the issue I'm having. You can check it out ...
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2
answers
3k
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Is there different between 'if' and 'ternary operator' in GLSL?
I'm practicing GLSL on ShaderToy
...
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1
answer
295
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draw on cubemap with help of geometry shader each triangle covers each cubemap face (why??)
I want to do some complicated stuff but have problems with my geometry shader / FBO bindings.
To hold it as easy as possible I reduced the code to a minimum. If this works, I could continue the hard ...
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2
votes
2
answers
636
views
OpenGL - Recreate position in viewspace from depth values
Current state:
I belive the reconstructed positions are correct. However, I still have the same problem as all the time. When I rotate around my single pointlight appears to be moving around also.
I ...
- 126
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0
answers
329
views
Combine box shadow with a signed distance field
I'm using 2d signed distance fields in my current project for drawing shapes (example: https://www.shadertoy.com/view/4llXD7) and I want to add drop shadows to them. At first I thought I could exploit ...
- 111
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1
answer
2k
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How to work around the pointer limitations of GLSL?
(I am new to Computer Graphics in general)
I am learning how to ray trace from a book called ''Peter Shirley - Ray Tracing in One Weekend''. In the book, the code is written in C++. I have ...
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0
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320
views
How could I remove this colour interpolation artefact across a quad?
I've been reading up on a vulkan tutorial online, here: https://vulkan-tutorial.com. This question should apply to any 3D rendering API however.
In this lesson https://vulkan-tutorial.com/...
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1
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1
answer
338
views
Does atomic functions on same memory location cause an performance issue?
is it worse to do for each invocation an atomicAdd on the same memory location than doing for each invocation an atomicAdd to a unique memory location? (I know, atomicAdd does not make sense when each ...
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2
votes
1
answer
164
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Rendering moist/wet materials like human anatomies for surgical simulators
Real human anatomies look wet/ moist when operated. I am looking for some good methods for rendering anatomies in a virtual simulation, and hence I have done a literature survey on 'Rendering wet ...
0
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1
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76
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Closest sphere on segment
I am trying to get a segment closest point on a surface and display a circle (or sphere in this case) at that position.
I actually get the correct position but I can't get a uniform sphere based on ...
- 1,219
3
votes
1
answer
214
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OpenGL task/mesh shader extension NV_mesh_shader not behaving as I expected
I am trying to get up to speed with the NV_mesh_shader extension from NVidia (on my RTX2080). Samples are rare, so I tried to come up with my own small sample.
I am rendering a sphere (20 triangles) ...
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