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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64 views

How to pack 3 floats into one?

I am doing some animation jobs. I need to pack some pivots into UV and then my shader can read them. I need to pack 4 float3 into a float4. Therefore, I need to pack each float3 into a float. ...
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1answer
58 views

Shader or formula that distorts inward

I am looking for a shader (or at least the right terminology) for crushing an image. It should be something very similar to barrel distortion, but instead of the center crushing outward to the edges, ...
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29 views

Optimizing texture fetches with higher mip levels

Let's say I have some shader program in DirectX or OpenGL rendering a full screen quad. And in a pixel/fragment shader I sample some huge textures at random texture coordinates. That is one same ...
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67 views

Compute normal based on Voronoi pattern

I am applying a 3D Voronoi pattern on a mesh. Using those loops, I am able to compute the cell position, an id and the distance. But I would like to compute a normal based on the generated pattern. ...
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18 views

Unlit shader emulation in usdz

How do you "emulate" an unlit shader in the .usdz file format?
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1answer
51 views

What is a 0 “null” normal map? Or Unlit shader

Does anyone understand normal maps and what would color a uniformly 0 normal map be? I'd like to convert a standard shader into an unlit shader, so (I think?) the idea is that the normal map should ...
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1answer
76 views

GLSL - increasing line spacing with y

I'm trying to force perspective into the horizon of a Shadertoy scene by drawing horizontal lines at decreasing distances as y grows to create an outrun-esque scene, but can't figure out which ...
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1answer
35 views

What are the type constants that the documentation for glGetProgramResourceiv() refers to?

Quoting the Khronos OpenGL documentation pages for the glGetProgramResourceiv() function: For the property GL_TYPE, a single integer identifying the type of an ...
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0answers
36 views

How to render multiple shaders per mesh

I've tried looking everywhere, but I just don't get it. How is multiple shaders assigned to a mesh if you can only bind a single shader in OpenGL? Assume I have a mesh with a texture shader and now I ...
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0answers
61 views

Implementing GGX VNDF importance sampling with DXR

I am currently implementing the GGX specular BRDF in a DXR raytracer using the importance sampling method describe by Heitz I am sampling the VNDF with: ...
2
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0answers
52 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
22 views

Confusion about glVertexAttribPointer and non-active attributes

When binding an attribute index using glVertexAttribPointer, what happens when a later bound program does not contain an attribute at said index? Is the behaviour undefined, or is the attribute ...
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1answer
197 views

Why is OpenGL recompiling my depth map vertex shader based on the GL state?

I've written a shader that writes depth to each face of a cube map, as part of rendering cube map shadows for a realtime 3D engine I'm writing with OpenGL and C++. The shader transforms each vertex ...
2
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1answer
75 views

Use glTranslatef and shaders?

In newer OpenGL it's encouraged to use shaders and pass the model-view-projection as parameters. But what if I drew a complex object, and wanted to translate/rotate it and draw many copies? For ...
2
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0answers
50 views

Screen space reflections become warped when looking up or down

I have been experiencing issues over the past few days with implementing SSR on water into my engine. Looking straight forward, it appears to be alright. However, when I look up or down, the ...
2
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1answer
72 views

Represent shape as particles

Input: Triangles which make up an arbitrary shape. Each triangle is represented by 3 3D points. Output: A set of particles which fills up the inside of the object (see image). I have read the ...
2
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1answer
82 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'...
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2answers
160 views

Why does Cubemap have 6 individual textures?

I am learning about Cubemap and I learned that A cubemap is basically a texture that contains 6 individual 2D textures but my question is Why does it contain 6 individual texture ? and also I've read ...
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1answer
181 views

shaderc compile through api with #include

I'm using shaderc to compile glsl code in to spirv module and pass to pipelie in REAL-TIME. I want to use #include to reuse some of the shader code but shaderc is having problems recognizing it. Any ...
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1answer
214 views

Sphere Texture Mapping Algorithm

I am trying to generate UV coordinates automatically to map a texture on a sphere. The problem is with seams when going from 0.8 to 0.2 there is a discontinuity and interpolation in fragment shader ...
2
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1answer
156 views

2D Line of Sight + Visibility Calculations

I am currently working on an algorithm to calculate visibility in a 2D top-down level. The level contains actors, with position and "sight" information walls, ...
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1answer
104 views

Where should I learn shaders as a vulkan user?

I have no prior experience with any other graphics low level libraries and I have barely any clue how shaders work, any book related to shadings is bloated with opengl code and is demoralizing.
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0answers
61 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 ...
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1answer
101 views

Ray tracing the next week: understanding Instances

My question is not about the code, but it's about the approach used by the author Peter Shirley (and apparently common practice in ray tracers) of handling Instances. To understand the question it's ...
2
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1answer
96 views

Is it possible to bind dynamic texture samplers to a shader in DX12?

So usually texture samplers are set directly in the D3D12_ROOT_SIGNATURE_DESC structure in DX12, at least that's how I've been setting them. I was wondering if it's ...
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1answer
133 views

OpenGL Unable to retrieve the values of data sent to shader using textures

I've been following these tutorials and i can't figure out how to send data to shaders using textures. https://en.wikibooks.org/wiki/OpenGL_Programming/Scientific_OpenGL_Tutorial_02 In this tutorial ...
2
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1answer
66 views

Is there an analogue of OpenGL's ImageLoadStore in DirectX 12?

I'm trying to port part of an OpenGL program into an existing DirectX 12 software, at some point in their shaders they use OpenGL ImageLoadStore in order to store information in 3D Textures without ...
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1answer
406 views

Convert RGB image to YUV420 using a hlsl shader

I am new to shaders and I need to convert efficiently an RGB image to YUV420. I can convert the RGB image to YUV420 with a simple c++ program that uses the ...
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1answer
299 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
159 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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1answer
223 views

Texturing an “infinite” plane

I am rendering an infinite plane as described in the following answers: https://stackoverflow.com/questions/12965161/rendering-infinitely-large-plane https://stackoverflow.com/questions/7380250/how-...
8
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2answers
987 views

Why are oct trees so much more common than hash tables?

When reading papers I commonly find Oct tree implementations of geometry representations to sort the data. However whenever I think about the problem hash tables seem better overall. Hash tables have ...
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1answer
469 views

Is a single shader and 1x1 pixel white sampler more efficient than frequent switching between shaders with and without samplers?

I have some existing OpenGL code that I am porting to Vulkan. The question is somewhat relevant to both OpenGL and Vulkan. I am rendering some primitives using textures, some single channel, others ...
2
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1answer
98 views

LoopBlinn Cubic Curve Rendering - Serpentine arteffect

I am trying to implement the Loop-Blinn cubic curve in java using the following source codes GPU-Curve-Rendering and WebCore. Both of them are showing few arteffects and i cannot figure out why. Here ...
2
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1answer
263 views

How to match Blenders polynomial lens distortion model with GLSL?

I'm trying to re-implement Blenders (libmv) polynomial lens distortion model using shadertoy, in order to apply the lens distortion in another application ideally by generating a STMap for that. I ...
2
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2answers
592 views

How can I draw this style of grid?

I'm trying to write code (in any language) to render this 3D grid, matching the look and colors as closely as possible:
7
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1answer
209 views

How does this small fractal shader work?

I would like to know the magic behind this tiny fractal shader; I didn't really understand the code and the mentioned thread... Is there an accessible explaination? https://www.shadertoy.com/view/...
2
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1answer
522 views

What is shader warming, and why does Direct3D seem to avoid it?

I am involved in a project that had been modified to run on Apple and Linux computers, when it was originally Windows only. Specifically, Metal and Vulkan renderers have been written alongside the ...
4
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2answers
2k views

Can i compile my shaders to SPIR-V without using glslangValidator?

I'm making a cross-platform application, and i need my shaders to be compiled to SPIR-V for both Opengl and Vulkan. It seems that the only way to do so is to call a separate program, called "...
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0answers
55 views

Evenly distributed point cloud for a grass renderer on a sphere

I'm trying to add some details like grass, rocks, trees, etc. to my little procedurally-generated planet. The meshes for the terrain are created from a spherified cube which is split in chunks (...
3
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2answers
457 views

Why are depth buffer values clamped to (0, 1)?

This is a simple question. I know that in OpenGL or other graphics API, the values stored in the depth buffer are automatically clamped to (0,1). I just want to know why people do this instead of ...
11
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2answers
4k views

Why are normal maps blue and purple in color?

I am learning about normal mapping. I understood that RGB values are converted into XYZ, but my question is how is it converted and why is the normal map blue and purple in color?
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1answer
63 views

Difference between using + and * operator after tex2D to add albedo color?

I have a two different codes with a little difference Case 1. I used a + operator before _myColor. ...
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0answers
47 views

Simulating vanishing points shader

How do I create a vertex shader that allows to choose 3 non aligned direction vectors and then allows to morph all vectors positions such that every vertex is remapped so that two vertices that are ...
6
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1answer
864 views

Why are tessellation shaders disliked?

I often hear that tessellation shaders aren't great for performance reasons. Something along the lines that if you try to use a tessellation shader, you'll find that the data you get out isn't ...
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0answers
433 views

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 ...
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0answers
149 views

Changing coordinate system from texelFetch to textureLod is breaking the algebra

I have a scene rendered using texelFetch() and I am trying to modify the shader to use textureLod() instead. This is the image generated with texelFetch: When I try to change the shader to use ...
3
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1answer
172 views

Importance Sampling in Unreal Engine Formula Derivation (Irradiance term)

I am currently trying to understand IBL in Unreal Engine, and there are so much things that I don't understand about the formula. Unreal approximate the specular term of shading equation by doing ...
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1answer
176 views

Controling order of execution of a (compute) shader on an array of vertices (data) in Vulkan

Is it possible to force Vulkan to execute a shader on vertices (data) in a semi-consecutive manner? For example, if the data passed to the shaders as a binary tree, shader would process it one layer ...
1
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1answer
61 views

Can you avoid querying for a texture location in OpenGL?

The way I learnt to send a texture to a shader is more or less ...