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.

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32 views

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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2answers
171 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 ...
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0answers
37 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 ...
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1answer
108 views

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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0answers
45 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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1answer
58 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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0answers
18 views

Open GL mapping/hash function on hexagon grid, translating from a cell ID to pixel location on 1d texture

I've spent the last three days trying to figure this out, my intuition about this space has been thrown out of the window. The problem is this: I have a hexagon grid making function that returns an id ...
2
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1answer
58 views

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 ...
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1answer
39 views

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 ...
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1answer
66 views

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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1answer
46 views

Force int array to compact memory

I have following structure which i use as an uniform buffer object. ...
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0answers
35 views

Per-object screen space uv issue

I am currently trying to sample a texture in screen space. This works well : ...
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1answer
47 views

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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2answers
59 views

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 ...
3
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1answer
140 views

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) ...
2
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1answer
68 views

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 "...
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0answers
52 views

Why is my ray caster is running much faster as a fragment shader compared to a compute shader

I'm trying to write a simple ray caster in OpenGL with C++. Previously, I have been using the fragment shader of a quad that covers the entire screen to do all the ray calculations. Now, I want to do ...
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1answer
48 views

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 ...
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1answer
39 views

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 ...
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1answer
119 views

What is wrong with my metalic 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 ...
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0answers
45 views

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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0answers
82 views

(Desperately) Need help sending an array of floats from Unity C# to HLSL shaders

I am currently working on implementing parametric curve based dynamic tessellation using GLSL. I have scanned the entire internet and I cannot find even a single good example of a GLSL shader which ...
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2answers
119 views

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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1answer
62 views

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 ...
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1answer
67 views

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 ...
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1answer
137 views

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 ...
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0answers
38 views

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 ...
2
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1answer
55 views

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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1answer
157 views

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 ...
3
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0answers
79 views

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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1answer
113 views

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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1answer
132 views

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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2answers
43 views

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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1answer
339 views

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 ...
2
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0answers
64 views

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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0answers
37 views

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 ...
2
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1answer
258 views

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 ...
1
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1answer
61 views

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 ...
2
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0answers
48 views

Communication between vertex shader executions

Look at this vertex shader: ...
2
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1answer
98 views

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'...
3
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1answer
1k views

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. ...
2
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1answer
137 views

Difference between isnan and comparison to self

In GLSL, what is the difference between isnan(x) and !(x == x)?
1
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1answer
261 views

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 ...
2
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1answer
457 views

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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0answers
91 views

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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0answers
74 views

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 ...
2
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0answers
69 views

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 ...
2
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1answer
579 views

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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1answer
296 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 ...
2
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1answer
80 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: ...