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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Subdivision vertex normal interpolation
I'm using GLSL 4.0 to write a subdivision routine that divides the triangles on an object through a geometry shader. I'm not using barycentric co-ordinates but vector arithmetic to output the triangle ...
- 111
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1
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643
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What framework shoud I use to implement the RAISR upscaling algorithm on the GPU?
I recently ran across the paper RAISR: Rapid and Accurate Image Super Resolution and thought it seemed like an interesting technique for scaling up images. However, I haven't seen any implementation ...
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What is a good approach for handling uniforms in modern OpenGL?
I'm creating a renderer using modern OpenGL (3.1 and up) and now I'm trying to create an efficient but flexible way of handling uniforms. I've been reading up on uniform buffer objects and on what a '...
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287
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How to output a 32 floating value in a render buffer with fragment shader
I would like to downsample my depth buffer and my normals.
For that, I take in input of my shader, the corresponding textures (depth, normal), and I write my new values in a multi render target.
I ...
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What are Jittering and Dithering
I've heard a lot about jittering and dithering but I would like to know more about those techniques, especially when used to avoid visible sampling in a fragment shader.
What are the differences ...
- 1,219
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153
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If statements in shaders - implications and consequences [duplicate]
I've heard a lot that in shader development, you absolutely need to avoid branching and so if statements.
But why? Does this have a real impact on performances on old and modern hardware or is it ...
- 1,219
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Unable to pass custom Matrix4 to GLSL as a uniform
I am fairly new to graphics programming and I am trying to pass a custom Matrix4 (non-glm) to my vertex shader by using a uniform.
...
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725
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Benchmark GLSL fragment shader
How can I benchmark a fragment shader?
What my shader does is basically lots of floating point operations, since it's doing some procedural stuff.
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400
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GLSL shader debugging [closed]
Is there any tool available for debugging GLSL shaders?
I have nvidia geForce 940m GPU which doesn't support Nvidia NSight and RenderDoc is great but it doesn't support GLSL shader debugging. I am ...
4
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1
answer
492
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Texture coordinates are not updating according to the vertex divisor specified
I want to draw a string of text with a single draw call (Instancing). I am reading a bitmap for each character texture. I want to pass the texture coordinates for each vertex of a quad (a single ...
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1
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541
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Binary scene voxelization using imageStore - problem
This problem has been haunting me for some time but I was busy with other things. I can't finish my GI technique (specifically occlusion step) without solving it.
I made a binary scene voxelization ...
- 2,119
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186
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What is the correct way to put different textures on different parts of an object?
I tried passing a variable from the vertex shader to tell the fragment shader whether or not I wanted part of an object textured. That way I could write another shader for the other parts of the ...
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947
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Exponential shadow maps sampling with PCF for sampler2DShadow instead of sampler2D
I am trying to make use of free hardware PCF sampling with sampler2DShadow and extend it to more samples.
So far I am sampling shadow map (...
- 2,119
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answer
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Attribute Location in Multiple Shader Programs
I'm trying to switch between the rendering of two different scenes as fast as possible using OpenGL.
For all my OpenGL related stuff I wrote a wrapper-class which provides a quite easy way of adding ...
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3
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583
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Texture coordinates projection
I have some classic texture coordinates and as a normal behaviour they follow the mesh's transformations.
I am trying to use the same texture coordinates behaviour but without being affected by the ...
- 1,219
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Eye Parallax Refraction
I am trying to implement the Parallax Refraction effect explained by Jorge Jimenez on this presentation: http://www.iryoku.com/downloads/Next-Generation-Character-Rendering-v6.pptx and I am facing ...
- 1,219
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Bezier Curve Tool Controlled by Mouse
So I have recently learned about Bezier Curves (quadratic & cubic) and have a thorough knowledge of how they work. In my graphics engine in DirectX I wanted to implement a Bezier Curve Tool ...
- 2,491
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268
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Special directional light type
I am currently trying to implement a specific directional light type.
This light type has been used in the game INSIDE and is called orthogonal spotlight (aka local directional light). I assume that ...
- 1,219
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Transforming fragment-to-camera to tangent space for parallax occlusion mapping
I'm trying to implement POM using this tutorial. As stated, I need to transform fragment-to-camera to tangent space and then pass it to a function.
tangent space is computed using Assimp. Well I ...
- 2,119
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3
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What is the difference between a Sampler and an Image variables in GLSL?
Reading through some code about voxelization I found the following line in the fragment shader
...
- 969
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2
answers
1k
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OpenGL: Purpose of transform matrix in Vertex shader where transform*vertex
I'm trying to understand OpenGL by using Processing OpenGL ES.
If I have an example Cube to render.
I've read that a vertex shader will be run once for each Vertex. The fragment shader will be run (...
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OpenGL specular shading - Gradient banding issues
I use Phong shading as my lighting model. Nevertheless, the specular shading produces gradients in the light cone:
Hopefully you can see the gradient starting from the lower left corner expanding ...
- 601
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answer
424
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Bug: Overly Sharp Highlights in PBR
I'm still working on my BRDF equations. Theoretically, all equations are correct, but the hilights are super sharp. I'm not sure if this is a result of me not using Image-Based Lighting (I currently ...
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258
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I dont understand how a GPU computes and branches, could you please help me fix this shader preformance
I have been working on how the GPU does parellel processing, and branching. However I am not yet to the point where I know how to make this shader more efficent. Essentially I dont know enough about ...
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GLSL - Merge two textures
I would like to display arbitrary 3d meshes with black edges (black outline, black ridges, etc.). Thereby I have created two different textures: One color texture and one anti-aliased edge texture.
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2
answers
262
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Can I use the same vertices to render multiple things?
I'm passing my vertex shader a bunch of vertices and color data. I would like to first render the triangles and then render a point at each vertex. The triangles render fine, but I can't think of a ...
5
votes
1
answer
759
views
mapping 3d texture on view frustum (or part of it)
I'm implementing volumetric fog in my OpenGL renderer. First I inject color into 3D texture using compute shader, atomic operations and shadow map visibility check. The information I use to compute ...
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619
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Is there a objective reason for matrix naming conventions?
I'm probably going to screw this up but.... In all the graphics libraries I've seen various matrices are often called something along the lines of
...
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answer
2k
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Creating an "ink spread" effect with a glsl fragment shader
I have dealt with glsl before, but I still have problems with my understanding of how to achieve certain kinds of effects with per-pixel processing. What I am looking to do is use a fragment shader to ...
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Why is my fragment shader not showing any colors?
I am basically following this tutorial about diffuse lighting in OpenGL.
I did some modifications but the idea is the same, at least that's what I think. However, my fragment shader is not showing any ...
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396
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Why does substracting -1 in shader fail for a float data type?
I am loading a texture in a WebGL fragment shader (GLSL version 1.00).
This is my working code:
...
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83
views
Why cant I use `#include` after upgrading my driver
After updating my graphics driver and trying to run this example from John Chapman's blog I got this error
...
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1
answer
4k
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Why does my Perlin Noise look "blocky"?
I tried to implement Perlin Noise by myself using just the theory (following flafla2.github.io/2014/08/09/perlinnoise.html). Unfortunately I was unable to achieve the look of the "original" Perlin ...
- 323
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117
views
gamma transform in webGLSL: when already done or yet to be done?
Color spaces issues are such a pain, especially when you create color data at the middle of the chain, and a pile of libs and apps separate this to the display... Here I only worry about gamma ...
- 1,266
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Guidance with Sphere-Map calculation in GLSL
I'm trying to achieve the same effect in OpenGL/GLSL as what Blender does when you add a texture, set to "Reflection"
This ultimately is a way to fake specularity, or "metallicness" if I get it right....
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2
answers
670
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Clearing but not drawing objects
I was trying to draw a plane and cubes in a framebuffer but nothing is drawing in that framebuffer besides clearing it with a color.
Here's the code...
...
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1
answer
6k
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Loop performance in a shader
I am wondering what's the best way to integrate a dynamic loop function in a shader?
First, it seems that dynamic arrays are not possible. So, is it better to create a maximum size array and only ...
- 1,219
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answer
245
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Shadow map projection issue
I am using Unity but this question might not be proper to this engine.
I have projected the shadow map onto this sphere but there are grazing shadows. Is it possible to avoid it or to correct it as I ...
- 1,219
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1
answer
646
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Methods for grid traversal in a glsl pixel shader?
I'm working on a shadertoy "snake" game, using the new multi pass rendering abilities to save game state between frames.
I'm using raytracing to render the board (an AABB), and am planning on using ...
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4
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1
answer
529
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Shader won't work
I have managed to implement a garoud shader with specular lighting efects in Processing 3.0 . Now I am trying with a fragment Phong shader but cannot make it work. I can´t find where is the error. It ...
- 185
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837
views
Flat shading for non-planar polygons
I'm trying to figure out how to properly implement flat shading for meshes containing non-planar polygons (using OpenGL/GLSL). The aim is to obtain something similar to the result Blender gives (all ...
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2
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808
views
OpenGL vertex color
Why do I need to specify the same name for color input in fragment shader and output color from vertex shader?
...
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1
answer
280
views
How to set the GLFW OpenGL target?
I'm programming on a Mac and I'm learning OpenGL in the library GLFW.
My problem is that my Mac supports OpenGL up to version 4.1, but when I try to compile the shaders with ...
10
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1
answer
1k
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WebGL Omnidirectional Shadow Mapping Issue
First of all, I want to say that I've read a lot of post about shadow mapping using depth maps and cubemaps and I understand how they work and also, I have working experience with them using OpenGL, ...
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Indexing gl_TessLevelOuter[] with gl_InvocationID on a tessellation control shader
I'm using hardware tessellation to render a terrain mesh with variable LOD.
I have this snippet on my tessellation control shader:
...
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How to convert a thread ID into Screen Space Coord in an OpenGL Compute Shader?
I've written an implementation of the sphere tracing algorithm in OpenGL 4+.
As an experiment/toy project, I'm re-implementing it using the OpenGL 4.3 compute shader, but I'm having trouble with the ...
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402
views
Can't get output from a GLSL code
I'm trying to learn GLSL, I'm following this tutorial. I've done everything according to the tutorials but I can't get any output from my code. As you see I'm checking for both compile errors and ...
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2k
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Shadow Mapping artefacts
I've been playing around with shadow mapping in OpenGL using depth textures. The depth texture is fine and I can map it onto the scene but I have some strange artefacts on the back of the object:
My ...
- 193
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964
views
Shader uniform performance
I'd like to know if there's any performance impact based on how I struct my shader uniforms. For instance, is passing 4 floats worse than passing a single vec4?
- 1,236
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4k
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Do I need to rebind uniforms or attributes when changing shader programs?
Rendering the scene usually involves more than one shader program which, in my case, all use the same attributes and share at least some of the uniforms. To have them working properly, I currently ...
- 1,310