Questions tagged [fragment-shader]
The fragment-shader tag has no usage guidance.
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Question regarding Memory-Efficient Order-Independent Transparency with Dynamic Fragment Buffer
I am currently reading the pdf regarding Memory-Efficient Order-Independent Transparency with Dynamic Fragment Buffer.
in there it is proposed to do two steps before sorting the fragments:
First, for ...
0
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1answer
50 views
Tiling in GLSL creates unwanted seams
I'm writing a shader that creates a grid with coloured tiles. The color is derived from a pixel at that location on a texture. But around the tiles I get these unwanted seams.
I can't seem to figure ...
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1answer
93 views
OpenGL transparency - object behind is not rendered
I'm trying to implement voxel world using OpenGL (Core 3.3). I've come across a problem with transparency. It looks like sometimes GPU decides to not render stuff that would be important. Can you help ...
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51 views
Examples of cases where you write depth value in Fragment Shader?
I've very less knowledge when it comes to rasterization and typical rendering in games and other applications. So I was reading up on the rendering pipeline and found that the hardware could do early ...
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1answer
61 views
Level of detail passed from vertex shader to fragment shader
I am looking at a sample code from a respected source and the mipmap level-of-detail parameter (float) is passed to the vertex shader as a uniform which then passes to the fragment shader without ...
1
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1answer
27 views
Is fragment shader run on fragments that are outside of rasterized geometry?
In deferred rendering, I first write world position to G-Buffer, and then in shading part, I want to use that information to reproject in the previous frame and then write the final color.
However, ...
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39 views
Order Independent Transparency: How to approach sorting
In an "Order Independent Transparency" implementation, one faces sorting a large amount of (as many as the number of pixels in the viewport) sets of data with relatively small number of ...
0
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1answer
153 views
gl_ClipDistance vs gl_CullDistance
Why are there very similar yet distinct arrays: gl_ClipDistance[] vs gl_CullDistance[]?
What would be some use cases where the ...
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1answer
197 views
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1answer
726 views
Understanding fragment shader coordinate system
I'm trying to create an infinitely panable grid using fragment shaders (C++/OpenGL/GLSL), and I'm having a bit of difficulty understanding the coordinate system.
This is my fragment shader code, ...
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1answer
230 views
What is the most efficient line algorithm using a shader program
I'm new to shaders and I have been experimenting with them in shadertoy. I'm trying to get a deeper understanding of the graphics pipeline and I want to implement some features using shaders. I want ...
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13 views
Calculating Bounding Boxes from JFA
I am working on getting bounding boxes from images using the GPU, I am using as an example this article by demofox which has included some shadertoy examples. The JFA algorithm is like this:
...
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18 views
Rendering different array types in the same vertex/fragment shader?
I have a pretty basic widget rendering, largely based upon the learnopengl.com "hello triangle." I'm actually using a tristrip to create two triangles, forming a semi-opaque square over the ...
1
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1answer
64 views
How to pass only the needed portion of the data calculated in a fragment shader to another fragment shader?
I have an image and I want to draw an arbitrary number of objects on that image. The center coordinates of those objects are calculated inside a fragment shader after series of image processing ...
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134 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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46 views
GPU accelerated 2D graphics library with signed distance functions
I want to create my own 2D graphics library using signed distance functions where everything is drawn on the GPU. Browsing the web I quickly found Inigo Quilez website that describes how to draw basic ...
7
votes
1answer
2k views
Performance of Compute Shaders vs. Fragment Shaders for Deferred Rendering
I have written a deferred renderer that can use either a fragment shader or a compute shader to execute the shading pass. Unfortunately, the compute shader implementation runs slower. I'm trying to ...
1
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1answer
99 views
Help me understand the voronoi shader
I am trying to understand the voronoi shader implemented in the Book of Shaders in the Tiling and iteration section: https://thebookofshaders.com/12/
Specifically how do these lines calculate the ...
3
votes
1answer
400 views
Interpolation in Graphics Pipeline
I am trying to program my own version of WEBGL graphics pipeline in python, however, I am confused as to where the color interpolation takes place in the pipeline. According to my research, it happens ...
2
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1answer
365 views
SDF rendering for large world
There are lots of cool things you can do with SDFs to render implicit surfaces. Most of the examples I've seen have been “all in the shader”, where the entire distance function is encoded in the ...
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0answers
112 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.
...
3
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1answer
1k views
gl_FragCoord and glViewport
I've been scanning the specifications for both OpenGL and GLSL, and I can't find a definitive answer as to how exactly are gl_FragCoord's ...
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0answers
56 views
Anti aliasing thin features in textures
Assume I have a texture with a repeating line pattern. The lines are exactly 2 texels wide (really thin). Ans very spaced out (50 texels in between each line).
I am now struggling with the ...
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0answers
82 views
Trying to optimize texture mapping
We are developing a PPI plot for a radar system, similar to the following:
NOTE: 1 radial is defined as a single slice of data within the circle, and 1 range gate is defined as a single point along a ...
2
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0answers
73 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
140 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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2answers
494 views
Writing data to a shader resource at runtime in DX12
I'm hoping to port my existing toy raytracer to a window so that I can see samples accumulate over time. And then port over to Pixar's pmj02:
https://graphics.pixar.com/library/...
5
votes
1answer
453 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 ...
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118 views
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1answer
564 views
Curve rotation in GLSL fragment shader
I'm trying to figure out the correct math to rotate and translate a curve displayed in a fragment shader.
What I try to accomplish is to define a curve, for example a sine curve, in a local ...
5
votes
1answer
1k views
Manually fetching 8 neighboring texels from 3D texture greatly decreases performance
I'm implementing manual interpolation between texels in a 3D texture to be able to discard some of them when needed. Compared to hardware interpolation, this process takes a lot of time. If I simply ...
2
votes
2answers
98 views
Shader cannot move texture x, y location
Crossposted https://forum.openframeworks.cc/t/shader-cannot-move-texture-x-y-location/29395
Hello I am trying to move the x y location of the texture using this code but it doest not work.
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votes
1answer
116 views
gaussFactorForOffset cannot call a non-function how to fixed this code?
Crossposted here http://forum.lwjgl.org/index.php?topic=6724
Hello guys I am trying to blur image using fragment shader but it is not smooth.. I search the internet and I found similar problem... ...
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1answer
1k views
Is it possible to override or disable blending per pixel
I'm rendering transparent objects in separate framebuffer then compositing it with opaque one to get final image.
The transparent pass has additive blending:
...
7
votes
1answer
1k views
Ray tracing - partial derivatives for texture lookup
I'm doing some ray tracing on GPU using a fragment shader...
How can I calculate texture coordinates partial derivatives with respect to screen coordinates so I could perform filtered texture lookup ...
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0answers
76 views
How can I draw a line whose position is given in UV space and its width in screen space?
In a fragment shader, I need to draw a line at a given value of u. The shader is applied to a planar polygon mesh that's being drawn in the scene with a perspective camera. (It isn't a full-screen ...
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1answer
379 views
Z buffer working in OpenGL
After Z-Buffer Testing does the fragment shader run on the discarded fragments?
Does the Z-Test happen after the fragment shader runs?
Please, tell me the step by step events that occur in the Z-Test....
6
votes
2answers
5k 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 ...
5
votes
1answer
4k 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 ...
6
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0answers
892 views
OpenGL texelFetch causes black stripes
THE SHORT VERSION
In my fragment shader I'm reading (using texelFetch) multiple times the same texel from a texture (created by another fragment shader) and write it to the output render buffer. ...
3
votes
1answer
228 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 ...
5
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2answers
134 views
Will the gaussian kernels in this fragment shader be computed for every fragment?
I am running this fragment shader on every pixel on screen. I am trying to make it as efficient as possible. BTW I am running open gl es 2.0.
The code segment below is only a sample from the code, ...
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1answer
1k views
Using a LUT to speed up a trig heavy shader for mobile devices
I am trying to get this shader to run on a really old iDevice, as well as eventually Androids.
Even when I reduce the code down to 2 sine functions per fragment the shader runs at about 20fps.
I ...
4
votes
1answer
710 views
How to correctly implement Lambertian BRDF with point light
I'm implementing a simple Lamberitan BRDF in GLSL, using a point light source. My fragment shader simply returns light_colour * 1.0/PI * cosine, which should model ...
1
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1answer
203 views
How to ensure a fragment shader only runs once
I am trying to programmatically figure out how many "texture2d " calls the gpu can make before the fps drops below 60fps.
My current way of doing this is to have a fragment shader with a for loop ...
1
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1answer
389 views
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:
...
5
votes
2answers
361 views
In a shader, how to store fragment coordinates in a spatial partitioning from one pass to the next?
I have a post-effect camera-shader in which I want to implement a simple spatial partitioning of the screen between two passes of the fragment shader.
The first pass should divide the screen into ...
2
votes
1answer
180 views
Count number of green fragments that are within a given distance from each screen fragment
First of all, let me explain what I am really trying to achieve. In a post-effect shader acting on a camera-renderer, I want to change the color of each fragment depending on how many green (RGBA = 0,...
3
votes
1answer
516 views
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 ...
11
votes
1answer
8k views
Why is accessing textures much slower when calculating the texture coordinate in the fragment shader?
When using textures in GLSL, it is best to calculate the final texture coordinates in the vertex shader and hand them over to the fragment shader using varyings. ...
