40
votes
Accepted
How to do color post processing in WebGL, when you can not read the color of the current pixel?
This is not a WebGL 2 restriction. This is fundamentally how GPUs and their 3D rendering APIs all work.
Because they're designed to render many triangles and fragments in parallel, they structurally ...
- 130k
29
votes
Accepted
How do I write a shader that lights up when objects are near a surface?
A general outline:
Create a depth map of your scene without the shield. You can get this effectively for free, since transparent objects are often rendered in a later pass anyway. Otherwise, you can ...
- 924
12
votes
Accepted
How to make a 2D neon-like trail effect in Unity
To achieve this effect my friend has created a custom sprite, we played around with all sorts of sprites and you can customize this part to your liking. The shader I've written for this effect, takes ...
- 3,126
7
votes
Accepted
How to pass a big (60+) amount of variables to an HLSL pixel shader?
Use several constant buffers and group variables together based on how often they change.
If your variables are fairly static ( or just huge ) you may be better off converting values into a texture ...
- 246
7
votes
Accepted
How do I calculate UV space from world space in the fragment shader?
Do I understand correctly that you want an effect somewhat like this?
(If I'm way off, you may need to edit your question to include more description of what you're trying to do and why)
Here I have ...
- 130k
6
votes
Accepted
Pixelation shader explanation?
This is a pixelation shader, it seems. What it does is, it divides the screen into tiny rectangles, the side of each rectangle is determined by the values dx and dy. The smaller the value of ...
- 1,492
5
votes
How do I write a shader that lights up when objects are near a surface?
It's just using the depth map. It renders the world then renders the shield and takes a difference between the shield's rendered z value and the depth buffer z value to tint the pixel more white.
- 584
5
votes
How do I wrap textures inside shader GLSL?
For people who come here from Google (like me), the shader version is:
fract (tex_coord.st)
this will loop coordinates in range 0.0 - 1.0
- 367
5
votes
Accepted
Does it make sense to do more calculations in the fragment shader if there are more vertices than pixels?
The calculation falls apart like so:
If every one of those 3 million polygons rasterizes to at least one pixel on average, then doing the operation in the fragment shader still results in it being ...
- 130k
4
votes
How do I wrap textures inside shader GLSL?
You don't set these values in the shader. You set them in your program, generally when first creating the texture (though it can be set or changed whenever).
If you've already uploaded your texture ...
- 504
4
votes
Accepted
Is there a way to get what pixel is being processed within the fragment shader?
There is, in the fragment shader, a variable called gl_FragCoord. This contains the coordinates of the currently executing fragment shader.
Note that (by default) a pixel at pixel coordinates (x,y) ...
- 3,203
4
votes
Accepted
Super formula on shader
Instead of atan(sf.y/sf.x), use atan(sf.y,sf.x). This works because it takes the sign into consideration. Dividing the two ...
- 155
4
votes
Accepted
GLSL: Issue replacing ternary operator with mix
The main issue is that (ONE3-b)/a may cause a division by zero. This causes the result to be NaN (Not A Number). In that case mix will also return NaN because ...
- 11.9k
4
votes
Accepted
HLSL texture sampler always returns white
The problem is this: the compiler optimizes the effect file.
So in your code only ONE sampler is created. However in reality you are using TWO textures. The first one, being the Texture provided as ...
- 4,037
4
votes
Accepted
How to make far block graphically better?
What you see is there because the textures are in a higher resolution than what they get drawn in. This results in a very pixelated look.
To "fix" this you can generate mipmaps. Mipmaps are the ...
- 14.8k
4
votes
Accepted
Depth Intersection Shader
This issue exists with the original shader as well, but is less apparent with the sphere mesh.
Notice how it looks alright when the model's vertices are close to the intersecting object.
But as they ...
- 246
4
votes
Accepted
Is linear filtering possible on depth textures in OpenGL?
Shadow maps, the way you're using them, don't filter well. The linear filtering does what it's supposed to, it's just not the thing you actually want for this context.
Take a sample point halfway ...
- 130k
3
votes
Accepted
Fragment shader, tint color problem
The problem was there
gl_FragColor = (1.0, 0 , 0 ,1.0);//vec4(texVal.rgb, texVal.a)*(1.0, 0 , 0 ,1.0);
it miss the vec4 name
...
- 293
3
votes
Shadertoy getting help moving to glsl
You have two options:
Use gl_FragCoord and pass a uniform variable for iResolution.
Everything else will work exactly like in ...
- 451
3
votes
Accepted
Stencil buffer VS conditional discard in fragment shader
Modern hardware performs early stencil testing using the same sort of tile-based approach as early depth. It can reject large groups of fragments before they make it to the fragment shader stage. That ...
- 2,298
3
votes
Accepted
Procedural Hatching
Yes, in fact I'm not sure of any other way you'd do it other than in the fragment shader. Here's some examples I found:
This ShaderToy uses a noise texture and another function to generate the ...
- 1,634
3
votes
GLSL - skewed parallax occlusion mapping
normalMapping should use TBN, Parallax Mapping should use transpose(TBN), and viewDirection should mul transpose(TBN).
- 31
3
votes
GLSL Fragment Shader compiles fine on certain computers
Remove the 'f' on your float constants.
It's not part of the GLSL language.
Source: GLSL Specification
If you do not put a #version NNN pragma at the top of your ...
- 11.9k
3
votes
Accepted
How can I create an outline shader for a plane?
If all we need is an outline around a rectangle, we can compute this analytically with the math of signed distance fields. :)
...
- 130k
3
votes
Accepted
How to implement multicolored flashing sprite effect like in Contra and the Messenger?
I think you could achieve this effect by using a rotating color palette. You can do this in GLSL by passing in a grayscale image and a 1D texture containing the color palette. You'd sample the ...
- 2,622
3
votes
Accepted
My Single Pass Gaussian Blur Looks Awful
Your sampling points are most likely messed up because you are not taking into account that texture texel size is in range [0; 1]. You need to divide offset coordinates by texture resolution. We can ...
- 1,424
3
votes
Accepted
Shader vs Working with Pixels
There are a few benefits when using a shader:
Speed
The GPU is faster in manipulating pixels. Ofcourse you can 'preprocess' the texture and that will be fine. It is under the assumption that you ...
- 4,037
3
votes
Accepted
How to decorate the floor with a grid?
One way to do a square pattern in glsl is with mod:
...
- 24.4k
3
votes
Accepted
Unity mesh shader for outlining colour changes
What you're finding here is that drawing the line based on your height above/below the boundary gives inconsistent results: in places where the height changes quickly (steep slopes), the outline ends ...
- 130k
Only top scored, non community-wiki answers of a minimum length are eligible