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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Force int array to compact memory
I have following structure which i use as an uniform buffer object.
...
- 55
2
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0
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85
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Per-object screen space uv issue
I am currently trying to sample a texture in screen space. This works well :
...
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4
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1
answer
251
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Operator associativity and 4x4 matrices - performance question
During vertex processing with 4x4 matrices, we might stack multiple transformations like projection, model-world, world-camera, etc. by doing something like this:
$$v_{final} = T_N \cdot ... \cdot ...
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2
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198
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What's more optimal - sampling one channel at a time or all channels at once?
I'm going through and optimizing some of my glsl code for a project, and have come across a scenario several times that I am not sure how best to optimize.
In summary - Is it faster to sample a ...
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3
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1
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847
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Shader that transforms a mercator projection to equirectangular?
I am new in the OpenGL - GLSL and trying to make a shader that taking a mercator projection texture as a source and converting it to an equirectangular projection texture.
Sample input: (1024x1024)
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2
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1
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133
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Creating glsl library
I have different functions for example normalmapping which I use all the time...
Now I thought about making a small glsl library.
My problem:
I don't want to have all functions within the same "...
- 1,136
1
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1
answer
511
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Passing mat4 array to GLSL succeeding but producing GL_INVALID_OPERATION
I'm currently passing an array of bone positions to GLSL for a skeletal animation shader; the positions are passing successfully but producing a GL_INVALID_OPERATION error.
I'm passing the matrices ...
user13304
1
vote
1
answer
630
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Implicit conversion in glsl shaders
When specifying member values for a structure consisting of float values like vec3 or mat3, is it guaranteed that if an integer ...
- 516
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464
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What is wrong with my metallic PBR shader?
I feel like my light conservation math isn't correct, but I am not sure which part is wrong.
Is reflected light supposed to influence the diffuse light?
Does metalness only affect the reflected ...
- 153
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187
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Specifying Fragment Shader Colors per Fragment (Instead of per Vertex)
I am learning about fragment shaders and have seen how by setting the colours of each vertex a triangle can be coloured via interpolation.
However what if we want to use our own function to manually ...
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2
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898
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OpenGL Compute Shader Shared Maximum
I'm working on an OpenGL compute shader in which each work item results in a single number output I'll call x, as well as a struct output with more information, I'll call y. What I would like is a ...
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89
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Wrong reflection
Here is a youtube video showing my problem:
youtube.com/watch?v=y8J7VhS2pkM
I think I'm either doing the texture lookup on the reflection texture wrong, or the reflection or view matrix is somehow ...
- 101
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188
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constant pixel width for any scale
I have a standard 3d camera/projection/model setup that renders rectangles with a WebGL shader.
Users can zoom out and fly anywhere.
I want to make sure that regardless of the scale, width of the ...
- 213
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1
answer
768
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Shader sampler2D uniforms instead of attributes
In the godot game engine (using opengl) it is not possible to define custom shader attributes.
A workaround is creating a sampler2D texture uniform instead and use vertexId (or in fact UV since ...
- 101
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158
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Problem with Quad-based Tessellation in GLSL generating incorrect vertex ordered tessellation
I am trying to perform quad-based tessellation using GLSL on Unity to be able to render polynomial-based parametric surfaces on a Unity quad. The quad-based tessellation using GLSL seems to be ...
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1
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119
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Point light illuminating only half of a scene
A point light is illuminating only a half of a scene in my small 3D renderer. It happens on every scene I've tried (conference room, cornell box, etc).
How do I go about debugging this? What could ...
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1
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471
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Retrieve real distance from depth buffer for shadow ray (vulkan hybrid rendering)
I'm trying to implement an hybrid renderer based on Vulkan extension VK_NV_ray_tracing. Basically, the rasterizer compute the albedo and depth map of the scene. Then I try to compute the distance from ...
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198
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Projective Texture / Shadow Mapping -- Why is the perspective division performed in the fragment shader?
I've just worked my way through this OpenGL shadow mapping tutorial.
While I understand the basic algorithm, one thing puzzles me:
During the 2nd render pass all vertices are transformed into the clip ...
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1
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1
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668
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Stumped on GLSL error C5041 (cannot located suitable resources to bind variable... possibly large array
I have an OpenGL based graphics engine coming along quite nicely, but I'm currently stumped on a problem that arose after adding a new vertex shader output array.
The vertex shader is outputing the ...
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1
answer
233
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How to compute normal in quartic Walton-Meek's Gregory patch in tessellation shader?
I am programing a tessellation shader in OpenGL which computes the quartic Walton-Meek's Gregory patch. I am searching for a local G1 method with good shading/visual results. So I am trying this patch....
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1
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2
answers
71
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Help with wireframe artifacts on mesh procedural UV texturing
My goal in my project is to render a procedural texture for a given mesh based on a predefined camera projection.
The way I choose to accomplish it is by creating tex coords based on only the visible ...
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1
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1k
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Shader code for putting an atmosphere over a planet
I'm working on a game set in space with procedurally generated planets, and I'm trying to write a shader that puts an atmosphere over a planet given the color of the atmosphere and the strength of the ...
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304
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Calculate the distance between two 3d points in screen coordinates
Given the Point A with the coordinates gl_FragCoord.xy, I have to find the distance to the Center of the cube face to which it belongs in screen coordinates.
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258
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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 ...
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1
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542
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GLSL Compute Shader doesn't run for large inputs
The shader takes an SSBO of Photons that have a position, direction, wavelength and intensity and each thread is responsible for tracing exactly one photon through the grid, where at each grid cell ...
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1
answer
110
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Wrapping normals around a sphere
I'm using a vertex shader to effectively wrap vertices on a sphere. Starting with world_position already after multiplying the vertex by the model transform matrix ...
- 121
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answers
64
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Communication between vertex shader executions
Look at this vertex shader:
...
3
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1
answer
328
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Strange dark spot when lighting in deferred rendering PBR shaders
It's probably something obvious but there seems to be a strange issue with lighting in my pipeline. I'm trying to keep everything in world space at the moment for simplicity but cannot figure out what'...
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1
answer
4k
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What do the OpenGL version strings from glxinfo actually mean?
Note: I wasn't 100% certain if this question belonged here or in Ask Ubuntu. I figured since it was about OpenGL programming I'd put it here, but if I should move it to Ask Ubuntu, please let me know.
...
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1
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269
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Difference between isnan and comparison to self
In GLSL, what is the difference between isnan(x) and !(x == x)?
- 41
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1
answer
533
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Mimic shadertoy in WebGL
I was following this guide for drawing circles using shadertoy. Now I am trying to mimic the examples behaviour in WebGL.
Here is a working shadertoy example I try to mimic. The code is not mine, see ...
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1k
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Clarifying vulkan glsl std140
So I have a uniform block that looks something lile this
{
mat4;
mat4[128];
uint[16]
}
The block should total up to 8320 bytes. After aligning by 256 bytes for nvidia, that brings the total ...
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0
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355
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How to hide a part of a geometry dynamically using a shader in three.js
I have a very big geometry in three.js and I want to hide a section of that geometry along an axis (for example every vertex with a Z>N must be hidden). My idea is to create a custom shader in GLSL ...
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0
answers
82
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Convey screenspace bounding box of rendering result
Imagine I render to an FBO some arbitrary geometry. Geometry can be rendered via single or multiple draw calls. For the sake of the question, assume I know nothing about geometry or transformation ...
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0
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81
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Show the edges between the clipping plane and clipped objects [closed]
I want to utilize shaders to not only discard fragments if they are on one side of a predefined plane but also render a contour along the intersection.
My fragment shader currently does something ...
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How does a GLSL Sampler2D read a Vec2 UV coordinate to determine UV range
I am working with an atlas shader that steps through various sprite tiles within a single png atlas page to playback an animation with sampler2D. Looking at the shader code, I would expect to have to ...
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1
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527
views
Convert shader from GLsl 1.50 to 1.30
I'm a newbie with OpenGl and I'm stuck in following the tutorial.
I found this tutorial with these shaders
...
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1
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280
views
Alpha component in color buffer affects RGB components?
I'm looking for a way to make my surface semitransparent, and for now i ended up using this configuration:
...
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2
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133
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Why is precalculating a distortion different from calculating it in the shader?
I have an application where I simulate a camera distortion. There are two ways to go about it: calculate the distortion per pixel in the shader or precalculate the distortion and store the distortion ...
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4
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1
answer
2k
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How does GLSL code get “loaded” and “compiled”?
I just wanted to find out for sure how GLSL code gets loaded and compiled.
Does the g++ compiler do it?
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1
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437
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Is it possible to access adjacent vertex data in tessellation evaluation shader?
I'm trying to render thick cubic Bezier curves using the whole OpenGL 4.5 pipeline:
I render a patch with 4 control points.
Vertex shader is simply pass-through to tessellation control shader.
...
0
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1
answer
320
views
Using depth texture to mask local pixels
I have a scene with camera facing billboards drawn with depth write off so they appear on top of other objects. I would like to draw each sprite so that any obscured pixels are drawn with a very low ...
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1
answer
732
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GLSL Debugging Volumetric light
I'm implementing basic volumetric lighting using deferred shading (gbuffer + render to screen quad) and basic shadow mapping. So, I am sending the position texture and shadow map to a separate shader,...
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1
answer
326
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SSAO random noise vector generation
I am currently trying to implement SSAO on my graphics engine. I am following John Chapman's tutorial here. This is a pretty popular article that is used as reference in many SSAO articles.
The part ...
- 493
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133
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glTexSubImage3D throws GL_INVALID_ENUMERATION on NVIDIA
I'm having problems when using the following statement on different GPUs:
glTexSubImage3D(target, 0, 0, 0, 0, width, height, layers, format, type, NULL);
on ...
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940
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How Skia uses OpenGL backend?
Skia 2D's one notable backend in OpenGL, but how does it work under the hood to render?
Say, we need to draw an anti-aliased circle. Does Skia:
make a quad (using 2 triangles) and paint the circle ...
- 111
3
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329
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Circular pattern aliasing in voxel ray tracer
I am doing a voxel based raytracer.
In other words, I first voxelize the scene using rasterization and I proceed to raytrace the volume in a 3D image to generate a final frame.
Currently I noticed ...
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515
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How to properly modify a ray in a raytracer to achieve camera rotation
I am trying to make a particular kind of raytracer, but there is some strange bug occurring when I attempt to rotate the camera.
As you can see, there is some important distortion ocurring when the ...
- 1,696
4
votes
1
answer
632
views
Is a branched discard to be avoided
When a simulating a camera, I may run into the situation that a black elliptic border is needed (rather than a rectangular image).
In this case I have the option to discard the fragment in the ...
- 1,541
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1
answer
16k
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How to use GLSL texelFetch?
I have read the OpenGl documentation of texelFetch, which is:
gvec4 texelFetch(gsampler2D sampler, ivec2 P, int lod).
I know the first argument "sampler" is just a texture. But I am very confused ...
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