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.
266 questions
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What's the difference of using smoothstep and linear interpolation for antialiasing?
I am currently writing a fragment shader where I want to draw an antialiased line. My first instinct was to calculate the color of each pixel based on the distance to the line. Something like: (using ...
- 33
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23
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Conversion of the Cubemap direction access vector to UV coordinates
In GLSL, cubemaps within a shader can be read with
gvec4 texture(gsamplerCube sampler,
vec3 P,
[float bias]);
so a direction is used. How can the direction ...
- 1,366
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2
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43
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Confusion about camera ray pdf
When I was studying a code base of path tracing implementation (done in GLSL), I notice the author returned a pdf of generated camera ray:
...
- 21
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28
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HealPix: Different results when comparing C++ and Vulkan
I have converted the algorithm for calculating the HealPix value from Lat/Lon values from C++ to GLSL. The result is saved in a BMP image and looks correct. Both algorithms (C++ and GLSL) use the same ...
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11
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Issues with vxgi implementation when rotating the camera
right now I have implemented vxgi algorithm. Voxelization is working fine, same for mipmap generation. But, I have an issue when I rotate the camera. Basically, it is not stable when it is rotated. I ...
- 101
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54
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Unit tests and code coverage tool for GLSL compute shaders
I use some compute shaders for some GPGPU usage. Each method of each shader must have unit tests. These unit tests must cover more than 95% of the code.
I am looking for tools that I can use to write ...
- 1,366
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19
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Tools to identify the cyclomatic complexity of GLSL code
In principle, cyclomatic complexity is a quantitative measure of the number of linearly independent paths through the source code of a program.
I am forced to keep the cyclomatic complexity of our ...
- 1,366
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102
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Projecting a texture onto UVs with GLSL
I am trying to project an image overlayed on top of a mesh in screen space back to it's uvs. The UV triangles do not always cover entire pixels so i get this. The red is showing where the texture is ...
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Reflective shadow maps sampling
I'm following the old RSM paper and I don't understand the sampling section. I understand that it's a disc pattern, that is more scattered away from the center and has some weights.
I don't understand ...
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1
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279
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Preferred GPU API to use for Steam Deck, Windows, Linux and MacOS support
Good people of the graphics SO community, I am new to Graphics programming or GPU programming in general but I have been a game dev enthusiast for over 4-5 years. I started learning about Graphics ...
- 101
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Slice a volume in GLSL using raymarching
I'm currently visualizing scientific data as volumes using Three and GLSL. I have a raymarching script that is pretty standard and colors based on a colormap I feed into the shader.
It looks like this
...
- 121
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43
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How can you tessellate degenerate triangles evenly?
If you use the tessellation shader for triangle patches, you can only set the following four values to define the tessellation structure of the triangle:
...
- 1,366
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Detecting edges on really small float-value differences
I'm working on a game that has a big proc. generated map (10000km by 20000km). The map generation is based on multi-octave perlin noise.
...
- 111
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OpenGL hash vertices by position does not work on shared tessellated edges
I have a triangular mesh with common vertices (VBO and EBO/IBO) that contain the normal vectors.
If I tessellate this mesh, the subdivision of the triangle edges of neighboring triangles has the same ...
- 1,366
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Shader ported from shadertoy does not behave in the same way
I tried porting the main "Image" shader here this. My results are somewhat similar apart from the fact that "IRES" does not seem to behave in the same way as it does in Shadertoy. ...
- 101
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68
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GLSL reflect function math correct?
In the documentation of GLSL - reflect given a surface normal $N$ and an incident vector $I$ the calculation being performed is reported as
$$
\text{reflect}(I,N) = I - 2\text{dot}(I,N)N
$$
I wonder ...
- 586
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2
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290
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Geometry Shader Not Working
So I seem to have some trouble getting a geometry shader working with "glDrawArrays(GL_LINE_STRIP, 0, 4);". When I omit the geometry shader and make some minor variable changes, the vertex ...
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42
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Why does my implementation of a sinusoidally time-varying color work so slowly?
I've been following TheCherno's OpenGL tutorials and I got to the point where I could render a square by using an index buffer. Now I wanted to vary the color of the square by using $$\frac{\sin(t) + ...
- 111
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185
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How to correctly handle rendering of ~600000, arbitrary colored 2D squares with WebGL?
Information
I have to render a map, that is rendered as a 2d collection of squares of different color, separated by white lines horizontally and vertically. There may be ~600000 squares surrounded by ...
- 101
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2
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457
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What's the type of iChannel[0-3] in Shadertoy?
I'd like to have a helper function in the Common tab that does something fancy with texture input and returns the result. I'd like the function in question to be able to use any ...
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88
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How are multisample samples partitioned in OpenGL, and at which points does interpolation take place?
As I understand it, with glEnable(GL_MULTISAMPLE), glEnable(GL_SAMPLE_SHADING) and ...
- 213
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118
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GLSL Uniform Layout Spec says member array stride alignment is rounded up to vec4?
in GLSL spec section 7.6.2.2 about Standard Uniform Block Layout, rule (4) says:
If the member is an array of scalars or vectors, the base alignment and array stride are set to match the base ...
- 1,871
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228
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How are strings for debugPrintfEXT handled in glsl?
Glsl does not support string / char data types, but obviously debugPrintfEXT works and takes some form of string. How are these handled in glsl?
Ideally I would ...
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266
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Is it possible to read arbitrary data at arbitrary array offset in glsl?
TL;DR
In a Vulkan / GLSL ray tracing program, I have several shader files, all accessing the same material buffer of arbitrary data. All materials have an arbitrary layout, e.g. one might be a float, ...
- 1,603
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1
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Need help understanding this simplification/optimization for a very basic GLSL shader
i'm currently following a tutorial on youtube to get started with computer graphics (shaders) and it contains the following GLSL code:
...
- 113
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264
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Vulkan backward-only path tracer with caustics
TL;DR -- who has discovered, in the past, a backward-only path tracer that generates caustics not needing extra convergence of any kind? I'm collecting similar algorithms, in order to fully understand ...
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2
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GLSL get min/max index of vec3
I have written a function in GLSL that returns the min index (index 0 is the x component, 1 is the y component, and 2 is the z component) of a vec3 variable.
...
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2
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2
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675
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is there an universal way to set a uniform?
so I'm working on a game engine.
It's partially python and c++.
One part that is currently a pain point is setting the uniforms for shaders.
Currently I have to define a behavior for all 50+ methods ...
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1
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143
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How to scale down noise frequency?
I'm making a space game and so far what I have is a system to generate spheres with noise on them, making them planets. I make a sphere, create noise data, write that data to an image file, and then ...
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71
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Curved world effect shader for heterogeneous mesh faces
I have a voxel based game, similar to Minecraft and want to apply the "curved world effect" like described here.
As I was using a per 1x1 face quad renderer, applying the effect went well, ...
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1
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130
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Numerically integratable fog volume feathering along a ray
I haven't been able to come up with a good solution for this myself, so I thought I'd ask if anyone else has any good ideas on how to approach this problem. Here's more or less what I'm trying to do ...
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0
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196
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GLSL : Extremely slow compilation when using loop
I am making multiple gradients with GLSL. However, when I started using a loop instead
of a lengthy else if condition, the compile time jumped from 2-4sec to 40sec !...
- 111
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1
answer
210
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Having trouble rendering entire sphere
I'm working on a program where I need to draw spheres. The method I'm using is creating an octahedron
And using tessellation shaders to subdivide it into a sphere, however there is a patch of the ...
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1
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408
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want bokeh blur with custom shapes
I have a 2d texture and a shape matte, the matte could be any shape, like a star, heart, and so on, and I want to use this matte to generate different-shaped bokeh blur, how can I do it? and normally, ...
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1
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144
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How can I test my GLSL code on different hardware?
I've written a game engine in OpenGL and developed it on my computer with an NVidia GTX 1060. I'm now ready to start releasing it into the wild but I'm worried about hardware issues. I compile my ...
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75
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Bottle neck in fragment shader because large number of texture2D call
Are there any way to optimize this flow:
The frame captured from camera (NV21 byte array)
Convert this frame to I420 format
Upload Y data to y_tex; U data to ...
- 1
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1
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221
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Splitting Floats To Texture Channels
I know, this is a silly question, but since I need this so often, I just want to double check that I made no mistake.
Working with most shader languages, a texture can store $8$ bits per channels, ...
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1
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186
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GLSL trying to bind two different layers from the same texture array as images. Should it work and if so what am I doing wrong?
I am new at this particular site in the SE ecosystem, but not to computer graphics in general. If I'm in the wrong spot feel free to redirect me.
My question regards glsl programming and binding two ...
- 125
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2
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158
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Porting from DXR/HLSL to Vulkan Ray Tracing Extension/GLSL
I am working on the port of a demo from DXR to Vulkan Ray Tracing extension using GLSL.
In DXR/HLSL space, there are RayTMin() and RayTCurrent() functions to retrieve the starting and the current end ...
- 309
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1
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223
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Best way for rendering Voronoi diagram from Delaunay graph mesh
I have a set of points, which I triangulate to a Delaunay graph to make a mesh.
Every mesh vertex has a unique colour, and I can render it without any problem. But I want Voronoi rendering to be ...
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1
answer
47
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Why shouldn't I discard faces during Tessellation control stage
In the discussion Here there was said, that discarding faces during Tessellation stage should be avoided. What are the reasons for that?
Right now, I am rendering a 3D geometry using Vertex, ...
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2
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286
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Why does GLSL smoothstep return 0 when all parameters are literal floats?
I was working through https://thebookofshaders.com/05/ when I came across some unintuitive behaviour of smoothstep. I wanted to understand it better so I replaced ...
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278
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combinatoric explosion of sampler2D, sampler2DArray, samplerCube
I use uber-shader approach and am having issues fitting within 16 texture units.
My material uses 3 textures: albedo, special, and normal map.
However, any of these textures can be regular 2D, or 2D ...
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100
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My n-body simulation doesn't form a galaxy
I'm trying to create a galaxy simulation using opengl with the compute shader and when I start my simulation, the galaxy with the spiral arms doesn't form, instead it goes into chaos. I noticed that ...
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1
answer
199
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Is there a good rule of thumb for the optimal / maximum number of instances to draw in a single call?
So let's say I want to draw a lot of textured quads to the framebuffer.
In each shader invocation, I will bind an array of indicies, an array of positions, and an array of textures to index into. ...
- 179
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0
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276
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What are the main concepts behind building the plasma effect with GSLS?
By the plasma effect I mean an animation that looks like this:
I have seen some codes, like these
https://www.shadertoy.com/view/Xst3zN
https://www.shadertoy.com/view/4tdGWX
and messed with the code ...
- 31
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0
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37
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How to make elevated parts of a steep plane seem darker than the lower surface? [GLSL]
I made a plane in THREEjs using Mesh, PlaneGeometry and ShaderMaterial. It's a very simple/basic form.
I applied a simple phormula to make the plain more steep. Now I'm trying to make the lower ...
- 111
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1
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745
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OpenGL compute shader workgroup synconization
I am calculating the Summed Area Table(SAT) of a texture with help of a compute shader in OpenGL.
The texture which needs to be summed, has a dimension size of more than my GPU supports (...
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680
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GLSL normalized texture coordinate to pixel coordinate
I've a texture (2048 x 2048) Pixels.
I am looking for an algorithm to transform the normalized texture coordinate [0 1] to pixel coordinate [0 2047]. This should be a perfect fit...
So when the ...
- 1,366
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0
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141
views
Is it possible to reduce aliasing in derivatives used to estimate normals from a texture?
I am generating a normal map for a texture for use in a PBR shader. I have a map for the diffuse texture, and I am estimating the normal at each point using the derivative of the texture's brightness....
- 111