Questions tagged [shader]

For all questions related to shaders, i.e. the programmable part of the GPU pipeline. For language-specific shader questions, see also the [glsl] and [hlsl] tags.

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1answer
117 views

What's the difference between two code in shader?

I'm doing a project with assimp. I got confused with the weird situation for me. I think the both code are exactly same, but the result is different. Why the codes act differently? (vertex shader) ...
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1answer
704 views

Shader storage buffer indexing by 4 bytes instead of 3?

I am trying to send rendering information for an instancing rendering using shader buffer objects. My current problem is that I have 2 shader buffer objects, one which works just fine, and another ...
5
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1answer
102 views

Role of gl.vertexAttrib

I'm re-learning WebGL, and I stumbled upon gl.vertexAttribPointer and gl.vertexAttrib. To my knowledge, gl.vertexAttribPointer tells the GPU how the data in the currently binded buffer relates to the ...
14
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2answers
17k views

GLSL. Can someone explain why gl_FragCoord.xy / screenSize is performed and for what reason?

I'm new to shaders and know that you can color pixels with gl_FragColor but sometimes there is this thing: ...
3
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1answer
237 views

Creating a vanishing point perspective shader

I have done my due hour of research before asking this question, it's a simple question, but I have found no hint at an answer online. I want the ability to extend an object infinitely in one ...
5
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0answers
312 views

In Metal, what performance advantages are there, if any, to using vertex descriptors and the [[stage_in]] qualifier?

Metal seems to provide two very different ways to access vertex data in your vertex shader. You can: Create an MTLVertexDescriptor object, which describes vertex ...
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0answers
104 views

Round Box SDF scaling issue

I am using the Inigo Quilez SDF function to generate a round box shape. The aim is to be able to control the shape scale, smoothness and roundness. I've achieved a pretty good result but I am facing ...
2
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1answer
173 views

DX9 Shadow map PCF issue

I am trying to do simple PCF with Unity but I am facing some issues and I don't know where they come from. If anybody has an idea... Here are two examples ...
7
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1answer
1k views

Constant screen-space-width rim shading

As of lately I've been studying a bit of shaders (in Unity), and am trying to recreate the "light-based inline" that can be observed in the latest Legend of Zelda. But maybe the task is a bit above my ...
4
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1answer
280 views

What is better to use for real-time computing Mesh - Plane intersection points, GPU or CPU?

I want to write plugin (library) for Unity3d (it doesn't matter which framework I will choose for this, question is ), for cutting arbitrary mesh with plane (for simplicity it will be plane for ...
6
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0answers
208 views

Dual paraboloid shadow texture edge seams

I implemented dual paraboloid shadows for point lights. The goal was to reduce the number of shadow passes. Also the target is GLES3.0 so no layered rendering is available. The shadows work, and ...
8
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2answers
1k views

How can I offset/shrink a triangular polygon in GLSL?

I need to offset all (blue) triangles, each independently of the others, using the vertex-shader. In order to manipulate the triangle as a whole, I've created custom (vec3) attributes for each vertex (...
3
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1answer
1k views

Phong shading in OpenGL: line of light from the center of the world

I implemented a Phong shader in GLSL, but there is a bug. What you are (supposed) to see down below: A point light source rotating around the center of the world, with a radiance of (0, 100, 0) A ...
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0answers
61 views

Specular Highlight Gray When Behind Model

What would cause this grayscaled backside? When my camera is behind my model I see a grayscale specular highlight. However, in front of it is perfectly fine. Here's my shading code. (Software ...
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2answers
7k views

Send Texture to Shader

I've been following the LearnOpenGL tutorials and I've come across a piece of code I don't understand. ...
4
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2answers
193 views

Strange behaviour in vertex shader with divisions

This is the vertex shader code: ...
4
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1answer
333 views

Special Texture Stretching without deformation

I am trying to achieve a special texture stretching effect in my shader. Here is how I define my uv before sampling my texture, nothing really special. ...
12
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2answers
2k views

Derivative maps vs. Tangent Space Normal maps

I discovered that some engines use derivative maps instead of tangent space normal maps. After some reading, it seems to be a really awesome way to replace tangent space normals but are there some ...
3
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1answer
269 views

Easing curves on the GPU?

I was thinking that I could pass a timestamp in (from requestAnimationFrame) to the vert shader, and just have my easing curves in the GPU instead of using (for example) Tween.js from the outside. Is ...
1
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1answer
286 views

How to organize Lights and Models?

I'm interested in how to organize in code (I prefer C++) lighting. Problem is: I have Scene which contains Model where model ...
4
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1answer
4k views

Alpha blending between two overlapping semi-transparent shapes

I am working on a 2D lighting system for my game. My approach has been to: Create a transparency quad representing 'darkness'. Create a stencil shader for light sources to clip from the darkness quad....
6
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2answers
4k views

Advice on how to create GLSL 2D soft smoke/cloud shader

I want to recreate this smoke/cloud effect which is used in the Arrival (2016) movie end credits. I uploaded a sped up version of the credits to see the smoke dynamics. http://streamable.com/n3309 ...
3
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1answer
429 views

GPU not reaching 100% usage when frame rate is dropping

I am making an iOS game using Unity. I am testing some shaders that I have made for the game, and in some cases the device will run at under 30 FPS but not have 100% device utilization. Sometimes a ...
3
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0answers
237 views

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 ...
4
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1answer
2k views

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 ...
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0answers
147 views

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 ...
5
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1answer
3k views

Fragment shader's output variables

EDIT: This is a duplicate of a question from stack overflow: https://stackoverflow.com/questions/9222217/how-does-the-fragment-shader-know-what-variable-to-use-for-the-color-of-a-pixel If you want to ...
4
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1answer
2k views

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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0answers
56 views

Rounding rules for mip level with point sampling

In shaders, when using SampleLevel intrinsic, if we pass 0.5 in the mip level parameter, and the sampler is a ...
2
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0answers
255 views

How does this function calculate normals of a mesh? [closed]

I have trouble understanding the following Javascript code. It calculates, given a mesh described by its vertices vs and indices ...
3
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1answer
596 views

How to properly direct light sample GGX in path tracing

I have been trying to implement the GGX shader in my path tracer based on this paper: Microfacet Models for Refraction through Rough Surfaces It's pretty clear how the importance sampling works, but I ...
6
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1answer
251 views

Mix shader looks wrong on my path tracer

I apologize if my methods seem way off because this is my first time trying to build a path tracer and I'm struggling quite a bit. Currently, I am trying to mimic the "mix shader" node in Blender 3D ...
3
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1answer
460 views

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.
5
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2answers
1k views

Is there a way to draw spherical objects without triangles?

It seems that in all existing graphics libraries, 3D objects are always described in terms of triangles. Drawing triangles can be implemented very efficiently on video hardware and since any 3D object ...
5
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1answer
2k views

Modern way of light sources in OpenGL?

In older versions of OpenGL there were things like: glLight(...) gl_LightSourceParameters The modern way of doing lighting is passing light source parameters manually to the shader in vao-s? Or ...
6
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1answer
1k views

What's the difference between Sample and tex2D

I am mainly using Unity but I think that it's not related to this engine, and I am wondering what's the difference between using tex2D and ...
6
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1answer
357 views

B-Spline patches on the tessellation shader. How to get the control points

I have a polygonal mesh with ngons in it. I want to make a tessellation shader to which I send only the regular quads in such a way that it can construct a B-Spline surfaces across it. I came across ...
5
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0answers
747 views

Percentage-closer Soft Shadows implementation

I am trying to implement the Percentage-closer Soft Shadows (PCSS) from NVidia inside Unity but I am facing some issue and I don't know where they come from and then, I do not know how to solve them......
5
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2answers
179 views

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 ...
5
votes
1answer
1k views

UV Coordinate Interpolation in Compute Shader

I am trying to get the screen space position of each pixel in a texture on a mesh and write it into a texture. I was hoping to use a compute shader to do this: ...
4
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1answer
1k views

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 ...
4
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3answers
430 views

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 ...
7
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2answers
1k views

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 ...
3
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1answer
259 views

What graphics techniques can be used to simulate a color nebula effect?

I've been playing around with more advanced graphics these days (beyond the basic 2D UI and image effects that the iOS platform offers), and I'm wanting to implement a visual effect similar to how iOS'...
5
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2answers
249 views

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 ...
3
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1answer
382 views

Rotating an Object Around an Axis

I have a circular shape object, which I want to rotate like a fan along it's own axis. I can change the rotation in any direction i.e. dx, dy, dz using my transformation matrix. The following it's ...
4
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1answer
161 views

Colorblending shader recompilation scenarios

Context As I was trying to learn more about Vulkan, I learned that certain fixed-function steps could be implemented with shader code from this video (at around the spot where he talks about the ...
4
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1answer
209 views

OpenGL ES Frag Shader - Branching

Working on optimizing a fragment shader which is slowing down my OpenGL ES 2.0 shader based game. This is used with a shadow buffer to determine if the fragment/pixel is inside a shadow volume. The ...
2
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2answers
860 views

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 ...
8
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2answers
198 views

Encode two R11G11B10F buffers into one using Y'CbCr?

We are trying to optimize Lighting in fillrate. Integrated graphics chips are very slow in memory access. There are two Light Buffers: one for Diffuse and one for Specular. Both use format R11G11B10F....