A programming language for OpenGL shaders.

learn more… | top users | synonyms

1
vote
3answers
654 views

Writing a shader once without using CG?

Is there a tool that can convert a fragment shader from hlsl to glsl or glsl to hlsl? I do not want to use cg since it is not able to work on mobile platforms. Is there a tool that can make it so I ...
10
votes
1answer
568 views

Special relativity shader in GLSL

I'm trying to implement a GLSL shader which helps understanding special relativity Lorentz Transformation. Let's take two axis-aligned inertial observer O and O' . The observer O' is in motion w.r.t ...
1
vote
1answer
2k views

GLSL - rewriting (geometry) shader from #330 to #130 version

I'm having trouble running example from: https://raw.github.com/progschj/OpenGL-Examples/master/07geometry_shader_blending.cpp My graphics card supports only #130 shaders version so I have to rewrite ...
2
votes
2answers
581 views

Lighting problems with Terrain

I'm in the process of learning Open GL and am having issues with lighting on my Terrian, I don't know if the issue is related to how I calculate my normals or the shader itself (I am using the shader ...
2
votes
0answers
298 views

Kinect User Silhouette Shader

I have this usermap from kinect's depth data (size is 320x280) and i want to display it on my game. The problem, of course it's ugly (first image) and i want to have beautiful effect like in the ...
3
votes
1answer
3k views

GLSL if-else statement unexpected behaviour

This question is related to this other one I asked a few days ago. Because I have finally get to the bottom of the issue, I have rather preferred to open a new question with a more detailed ...
7
votes
4answers
1k views

Impact of variable-length loops on GPU shaders

Its popular to render procedural content inside the GPU e.g. in the demoscene (drawing a single quad to fill the screen and letting the GPU compute the pixels). Ray marching is popular: This means ...
1
vote
1answer
188 views

Blur gets displaced compared to original image

I have implemented a SSAO and I'm using a blur step to smooth it out. The problem is that the blurred texture is slightly displaced compared to the original. I'm blurring using a 4x4 kernel since that ...
4
votes
2answers
2k views

Updating texture memory via shader?

What the title says.Is it possible to update a texture via a glsl shader ? Something like : //Read vec4 Pixel = texture2D(TextureID,gl_TexCoord[TextureIndex].st); //Write to texture memory ? vec4 ...
2
votes
2answers
627 views

Build-time GLSL syntax validation

Is there a way to validate GLSL syntax build-time instead of run-time? My application takes a long time to start and I want to know at the earliest possible stage that my shaders are ok. I'm using ...
7
votes
1answer
1k views

Not getting desired results with SSAO implementation

After having implemented deferred rendering, I tried my luck with a SSAO implementation using this Tutorial. Unfortunately, I'm not getting anything that looks like SSAO, you can see my result below. ...
0
votes
1answer
436 views

OpenGL Tessellation makes point

A little problem with my tessellation shader. I try to implement a simple tessellation shader but it only makes points. Here's my vertex shader : out vec4 ecPosition; out vec3 ecNormal; void ...
2
votes
2answers
990 views

Simple OpenGL program major slow down at high resolution

I have created a small OpenGL 3.3 (Core) program using freeglut. The whole geometry is two boxes and one plane with some textures. I can move around like in an FPS and that's it. The problem is I face ...
2
votes
1answer
2k views

How to detect GLSL warnings?

After compiling a shader with glCompileShader, I can call glGetShaderiv with GL_COMPILE_STATUS to check if the shader compiled successfully. I can also call glGetShaderInfoLog to get information about ...
0
votes
1answer
1k views

Making a surface transparent from blackness of texture

I am making a "halo" shader in unity using GLSL. And I've come to a roadblock. What I need to do is take a texture, like the following, and make it transparent according to the darkness of it. And I ...
8
votes
3answers
5k views

First time shadow mapping problems

I have implemented basic shadow mapping for the first time in OpenGL using shaders and I'm facing some problems. Below you can see an example of my rendered scene: The process of the shadow mapping ...
2
votes
1answer
1k views

GLSL compile error when accessing an array with compile-time constant index

I have this shader that works well on my computer (using an ATI HD 5700). I have a loop iterating between two constant values, which is, afaik, acceptable in a glsl shader. I write stuff in two arrays ...
9
votes
2answers
2k views

Sorting objects before rendering

I'm trying to implement a scene graph and in all the articles i've come across there is talk about object sorting. So you'd sort your objects by "material" for example. Now untill i sat down and ...
17
votes
1answer
11k views

in/out keywords in GLSL

I don't really understand how to use the in / out keywords in GLSL, and google is being uncharacteristically unhelpful. What exactly do they do? How would I use them if, for example, I want to pass a ...
4
votes
4answers
547 views

Shader compile log depending on hardware

I'm done with the core of my graphics engine and I'm testing it on every platform I can get my hands on. Now, what I noticed is that different drivers return different shader and program compile log ...
1
vote
3answers
720 views

GLSL mesh discard command?

Is there a GLSL command similar to the discard, but it discards the whole mesh and not just a fragment?
4
votes
1answer
646 views

My GLSL shader isn't compiling even though it should. What should I investigate?

I'm porting an iOS game to Android. One of the shaders I'm using wouldn't compile until I reduced the number of uniform variables. Here are the uniform definitions: uniform highp mat4 ...
5
votes
1answer
2k views

GLSL default shaders

I've been arming my engine with error checking code. I'll try to describe this situation to my best abilities. Whenever i load a shader and there's an error (file doesn't exist, compilation error, ...
1
vote
1answer
432 views

How to calculate the viewing cone radius at a distance in raymarching?

I'm "raymarching distance fields" (proper lingo: sphere-tracing) in GLSL. To implement cone-marching atop of it (and also to minimize the number of raymarching steps regardless of whether ...
0
votes
2answers
986 views

GLSL shader compilation

When i'm compiling a shader does it have to be complete? Can i use glCompileShader on a shader without a main() function? The OpenGL reference documentation has a nice writeup on program linking ...
2
votes
1answer
309 views

Steps to take before trying to implement screen space ambient occlusion

I very recently started learning modern OpenGL. I have implemented a wavefront file loader and a basic ADS shading model. At some point I'd like to implement screen space ambient occlusion. I tried ...
0
votes
1answer
913 views

CG/CGFX to GLSL

So, I'm making the painful move from my beloved XNA to OpenTK, and I'm stuck: Since I've got a LOT of existing shaders written in HLSL, NVidia's CG compiler seems like a natural way to minimize the ...
6
votes
1answer
2k views

How to invert background pixel's color

I'm writing a game and map editor using Java and jMonkeyEngine. In the map editor, I've got a brush done by wireframed sphere. My problem is: I want to make it visible everywhere, so I want to invert ...
0
votes
2answers
1k views

Can't render to FBO using a shader

I've added functionality so that I can render to a framebuffer (for post-processing and stuff). I can successfully render to my framebuffer and then render that framebuffer, but anything with a ...
4
votes
2answers
723 views

How Do I Raycast for a Spherical Harmonic Shader Using the iOS GPU?

I am beginning an Spherical Harmonics shader project for an iOS app I am writing. I have begun by reading this excellent in-depth paper on the subject (PDF) - http://bit.ly/aQmax3. The paper ...
2
votes
1answer
1k views

GLSL Shader Solution for Ambient Occlusion?

For the iOS app I am writing I want to incorporate some aspects of ambient occlusion for photo manipulation. Can someone suggest a GLSL approach that will work. Realtime performance is not super ...
6
votes
1answer
425 views

Weird problem with advect program in fluid simulator

I implemented 2d fluid simulator. Solver runs entirely on GPU. All works fine... on my work PC. But on home PC I have some awful glitches, and I can`t understand how to fix them. Empirically I ...
2
votes
0answers
2k views

How to implement fisheye effect with a GLSL fragment shader [duplicate]

I would like to render my scene with a wide FOV and then apply a fisheye distortion via fragment shader. How would this shader best be implemented? Update I try to reproduce a fisheye effect similar ...
2
votes
2answers
1k views

Optimizing gaussian blur with linear filtering

There's a few (here, and here) gaussian blur tutorials out there suggesting that you can essentially cut the number of texture lookups in a gaussian blur shader in half by exploiting the GPU's ...
5
votes
1answer
1k views

GLSL Editor and Debugger for MacOSX with ES2 support

is there a GLSL editor for the mac? I need it for iOS OpenGLES2 shader. How do you best debug shader? Regards
0
votes
1answer
715 views

Help understand GLSL directional light on iOS (left handed coord system)

I now have changed from GLKBaseEffect to a own shader implementation. I have a shader management, which compiles and applies a shader to the right time and does some shader setup like lights. Please ...
7
votes
2answers
2k views

Billboard rendering without distortion?

I use the standard approach to billboarding within Unity that is OK, but not ideal: transform.LookAt(camera) The problem is that this introduces distortion toward the edges of the viewport, ...
2
votes
3answers
1k views

Passing POD arrays to shader?

How do I pass to my vertex shader an array of N elements? From what I see I can only pass float arrays of 3|4 elements, vectors 2|3d and matrices, but I want to pass a POD array and use it like this: ...
8
votes
2answers
617 views

Sharing functions across multiple shaders

Simple question: In GLSL, is there a way to share functions across multiple shaders, or do I have to define all functions in every shader that needs them?
6
votes
1answer
662 views

GLSL subroutine not being used

I'm using a gaussian blur fragment shader. In it, I thought it would be concise to include 2 subroutines: one for selecting the horizontal texture coordinate offsets, and another for the vertical ...
8
votes
2answers
13k views

GLSL - one-pass gaussian blur

It is possible to implement fragment shader to do one-pass gaussian blur? I have found lot of implementation of two-pass blur (gaussian and box blur): ...
39
votes
2answers
4k views

How to render realistic ice?

I am trying to write an ice shader in Unity that looks good and at least semi-realistic. If the following shot (found on Google) was CG, what would its shader include? (the foreground cave). I might ...
1
vote
0answers
408 views

How to setup my texture cordinates correctly in GLSL 150 and OpenGL 3.3?

I'm trying to do texture mapping in GLSL 150 and OpenGL 3.3 Here are my shaders I've tried my best to get this correct as possible hopefully this is :) I'm guessing you want to know what the ...
4
votes
1answer
2k views

Proper way to do texture mapping in modern OpenGL?

I'm trying to do texture mapping using OpenGL 3.3 and GLSL 150. The problem is the texture shows but has this weird flicker I can show a video here. My texcords are in a vertex array. I have my ...
1
vote
1answer
1k views

Why doesn't my texture display with this GLSL shader?

I am trying to display a DXT1 compressed texture on a quad using a VBO and shaders, but I have been unable to get it working. All I get is a black square. I know my texture is uploaded properly ...
4
votes
4answers
7k views

How do multipass shaders work in OpenGL?

In Direct3D, multipass shaders are simple to use because you can literally define passes within a program. In OpenGL, it seems a bit more complex because it is possible to give a shader program as ...
2
votes
1answer
350 views

Update single entry in GLSL array

I have an array in my vertex shader like this: uniform mat4 MeshTransforms[20]; At the moment I'm just updating the entire array of matrices like so: int meshTransforms = ...
1
vote
2answers
1k views

How to achieve this particular screen filter with GLSL?

I know this may be a "short" question, but still here it goes. I would like to know how to achieve a post rendering effect, that looks like the following image from walking dead series: I will ...
5
votes
1answer
756 views

Can I use the default depth buffer when drawing to FBO?

How to attach default depth buffer to FBO? How to use depth renderbuffer buffer attached to FBO (after drawing to it) as a default depth buffer? Basically I want to use the same depth buffer for both ...
9
votes
3answers
1k views

Deferred shading - how to combine multiple lights?

I'm starting out with GLSL and I've implemented simple deferred shading that outputs G-buffer with positions, normals and albedo. I've also written a simple point light shader. Now I draw a sphere ...