A programming language for OpenGL shaders.

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21 views

glsl specular not working

ok, i'm a complete noob regarding shaders and all this, so i must be doing something really stupid, but i cannot get specular lighting to work. I've read a whole lot of different shaders on the ...
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15 views

Perspective divide: Why use the w component? [duplicate]

In OpenGL, I have read that a vertex should be represented by (x,y,z,w), where w = z. This is to enable perspective divide, whereby (x,y,z) are divided by w in order to determine their screen position ...
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1answer
9 views

Passing data into a vertex shader for perspective divide

In OpenGL and GLSL, I am just learning about perspective projection and the vertex shader. However, I am a little confused about what data actually needs to be passed to the vertex shader, and what ...
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30 views

Image speeds up while moving and or rotating instead of constant speed

I'm having a problem with rotating/moving an image. I've set one of my images to rotate on it's z-axis buy updating the angle, but when I run my game, the image starts slowly starts to rotate from a ...
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13 views

OpenGL, glDrawElementsInstanced behaving differently on NVIDIA GPU than AMD

I have an AMD GPU on my desktop, AMD HD 5770. I am working on a project on my desktop for over a year. In the scene, I have instanced grass and instanced trees. Everything is working fine on desktop, ...
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1answer
31 views

OpenGL ES God Ray Precision error

I have encountered the following (i think) precision error. (missing link need 10 rep) My source of inspiration was: (missing link need 10 rep) On the PC everything works fine, but on android it ...
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1answer
45 views

Create a “genie” effect in fragment shader GLSL

I have tried a while now to create a genie effect on a scrolling plane to emulate the background/floor from the Mad Hatter fight in Adventures of Batman and Robin (SEGA). Judging the way the 16 bit ...
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2answers
61 views

How do I start and stop a GLSL shader?

Is there a way to start and stop a shader?. I want to use this shader to sweep once over my texture and then stop. Does anybody know how to do that? void mainImage( out vec4 fragColor, in vec2 ...
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27 views

ETC1 texture opacity

I'm using the cocos2d-x engine and want to support etc1 on android devices for my game. For ETC1 i'm using the mali compression tool, and GLSL. Everything is working, but I can't change the opacity ...
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1answer
86 views

GLSL 2D Silhouette

I'm trying to render a silhouette of any entity behind foreground objects to indicate their position to the player. Here's an example of what I want to achieve, from Hyper Light Drifter: From what ...
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30 views

GLSL lighting shader with model scale

Basically, i'm just trying to find out where to insert the model scale into the lighting calculations. Ive searched the web, but amazingly, couldn't find anything dealing with scale + GLSL. This is ...
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1answer
44 views

ETC1 Support on android alpha problem (GLSL cocos2d-x)

I want to support etc1 in my game, but somehow it doesn't work (I'm using cocos2d-x C++ GLProgram* glp = new GLProgram(); glp->initWithVertexShaderFilename("testv.vsh", "test.fsh"); ...
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2answers
53 views

GLSL Fragment shader lighting lambert term

Just a simple question: Should I or should i not normalize the SurfaceToLight vector to calculate the lambert term on a GLSL lighting shader? I mean, here: vec3 CalculateLights ( void ) { vec3 ...
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1answer
37 views

OpenGL Shaders Ignored

I have been following this tutorial to try and start learning OpenGL. However, upon compiling my code, my triangle turns out to be black. At first I thought that there was something wrong with the ...
2
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1answer
74 views

GLSL 330 Core Bug? - Uniform variable will not set to value if it is named a certain way

In the code below I have a uniform variable named "vw_matrix" used in the calculation for gl_Position. When I run my program, a rectangle gets printed to the screen. #version 330 core layout ...
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0answers
155 views

Texturing Objects in OpenGL

Using OpenGL tutorials found here, I constructed an .obj file loader as well as a texture file loader using SOIL. I have an issue with drawing a textured object. (Shown here) Assuming I created the ...
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1answer
76 views

How can I blend up to 3 textures on a polygon without blend maps?

For my voxel game I need to blend up to 3 textures in the same polygon. It would be preferable if I could specify a texture id for each vertex, but other solutions are accepted as well. Here's an ...
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1answer
65 views

Error drawing two VAO, each one using different shader programs (vertex + fragment shader) in OpenGL Core 4.3 / GLSL 430 (SOLVED)

I am trying to draw over a GL_TRIANGLE_FAN one texture to render video frames, using shaderProgram1, and render above it some points (GL_POINTS) using shaderProgram2. By this way: (OpenGL Core 4.3) ...
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1answer
61 views

WebGL half float equivelant?

I'm trying to find a half float for the purposes of doing math in a fragment shader, not trying to have a half float texture. Is there an equivalent of the half float data type in WebGL? I know you ...
3
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1answer
132 views

2D day night mapping

I'm looking for this kind of effect MINUS the lights and snow (Another problem). It needs to change depending on the time of year. Doesn't need snow or city lights. Now I'm pretty new to shaders ...
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0answers
29 views

Slick2d - apply shader

I have a problem. I'm trying to apply a shader to the whole screen. Since I haven't used shaders before I don't know how to pass the texture to the shader. Everything else works... So here are the ...
4
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0answers
331 views

Skeletal animation in OpenGL

I'm using Assimp to do skeletal animation in my OpenGL application. I used Blender to export this one-boned model to a COLLADA file: The model has only one bone, called arm bone, that controls the ...
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1answer
64 views

How to only render fragments with Z from 0 to 1 in OpenGL?

I have been using OpenGL for a year now, but I just recently found out that OpenGL only clips vertices when the absolute value of the x,y or z coordinate is less than the absolute value of w ...
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1answer
61 views

how change branching logic to math equivalent glsl? [closed]

im totally newbie and this just for fun afaik lot of best practice suggest to minimize usage of branching. can you help me optimize below glsl especially on branch part? ( target 120 ) the bgcolor ...
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49 views

Shader - Simple SSS lighting issue

I am trying to create a simple subsurface scattering effect using a shader but I am facing a small issue. Look at those screenshots. The three images represents three lighting states (above surface, ...
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1answer
44 views

Can glsl main() have params or return a value?

I haven't ever seen anyone declare main as anything but void main() or void main(void) but I'm curious, is it possible to have a parameter or return value?
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1answer
109 views

Shader - Color blending

I would like to know how to blend colors in a specific way. Let's imagine that I have a color (A) and an other color (B). I would like to blend them in such a way that if I choose white for the (B) ...
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1answer
46 views

Modern OpenGL Texture Displaying Incorrectly [closed]

I've been working with this code and have simplified it to the most basic form possible, and even then I cannot get a texture to display properly at all. Here is the code: ...
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1answer
78 views

Shader - Convert vector into scalar

I am trying to convert a half3 as a simple half but I am facing an issue. As for an example half3(1, 0, 0) give me white but half3(0, 1, 0) gives me black. How can I convert properly a half3 to a ...
2
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1answer
106 views

How to handle the birth and death of particle without reading from the buffer

I've implemented a simple particle system where each particle has a position, velocity, age and lifespan stored in different SSBOs. Most of the data including all the position, velocity and age is ...
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0answers
53 views

Shader to mask image with polygon

I'm new to graphics programming and GLSL in particular. I'm working on a 2D game and the setup is as follows: There is an image on the screen (a sprite in the game engine [Cocos2d-x if it matters]) ...
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2answers
177 views

2D Hidden Object Silhouette Shader

Right now I am not using any depth information in my engine, but I just found out that it would be neat to be able to render the silhouette of important game objects that are "behind" something with a ...
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2answers
81 views

Problems with Rotation Matrices on Certain Axes

Here is what my rotation matrix looks like: public Matrix4f initRotation(float x, float y, float z) { Matrix4f rx = new Matrix4f(); Matrix4f ry = new Matrix4f(); Matrix4f rz = new ...
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81 views

Is Phong shading supposed to be so camera-angle dependent?

I'm not sure if I have a bug in my code or not. It seems like it's a bug, or at least a major shortfall. Here's two images of the same model at slightly different angles (by moving the camera): As ...
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2answers
62 views

Rectangular area light illuminance - colour banding

I'm currently working on an implementation of rectangular area lights but I am having some issues with the illuminance calculation, which gives me serious colour banding across the entire lit area. ...
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0answers
51 views

Confused About My Code Suggesting The Normal Matrix Is Equivalent To The ModelView Matrix

I'm learning environment mapping in OpenGL by following this page. In his vertex shader, the author calculates the vertex normal in eye space with the following code: nEye = vec3(viewMatrix * ...
3
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2answers
127 views

Blending vs Texture Sampling

I don't think this question has been asked before as I couldn't find any information about this on the internet. Lets say I want to blend two textures together: A texture containing the result of ...
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0answers
44 views

change position/orientation of a bone using assimp

I have been using assimp to import rigged models and animations. I followed this tutorial for skeletal animation and I have got it done properly. The part that I am trying to do now is to orient a ...
3
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1answer
207 views

How to generate a RGB * a texture for a glow effect in GLSL?

I would like to create a glow effect in GLSL, there is a tutorial that explains how we multiply RGB * a : I have some questions : is it an operation that is in a fragment shader, where RGBa is ...
2
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0answers
84 views

OpenGL Planet Generation - Simple Matrix Issue (Planet “Spins” With Mouse)

I originally asked this question on StackOverflow & was directed here by a commenter. Im currently working on a OpenGL planet rendering. I'm using the Tessellation pipeline. So far things are ...
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0answers
48 views

Can i use shaders in allegro without opengl?

I'm currently learning opengl but it seems quite complicated so i considered using some library like sdl or allegro. I noticed that allegro has some built in functions to create and attach shaders. ...
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0answers
55 views

Textured/Vertex Colored Shader fallback

I have this simple ShaderLab shader that I use for particles, among other things (it's more complicated than this but I have omitted the unnecessary bits). When I do not specify a texture, it falls ...
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1answer
260 views

OpenGL Shader Storage Buffer Objects array length problem

Ok guys, I think I have a very strange problem. I have an old laptop, but its HD 6370M currently supports opengl 4.4, so i decided to learn how to use some new features of this platform, so after ...
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1answer
169 views

How to use a buffer in GLSL to do a LUT-lookup?

I am currently on a medical application which needs different kinds (up to totally individual) lookup tables (LUT) for image display. And this done with 10bit finish. So it is most of the time ...
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0answers
28 views

converting HSLS gives error

I'm using the following parser: https://github.com/unknownworlds/hlslparser I also have the following code: /* * Bo Sun, Columbia University, All rights reserved * ...
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1answer
87 views

Calling Shader Functions Inside Other Shaders

I'm new to OpenGL and GLSL, and bit confused about calling conventions of shader functions. I'm trying to implement various procedural noise algorithms in GLSL. I'd like to have separate files for ...
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1answer
159 views

Dot based light mask with shader on sprites

So I have a scene, completely based on 2D sprites. I want to render "light sources" into a seperate frame buffer (so mostly dots around, for example, the centre of a flame) and then render that frame ...
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65 views

Invalid operation (1282) in GLSL vertex shader

My GLSL vertex shader works fine, but you if put a for loop inside or rename the uniform xxx to something else, it says the follwoing: Exception in thread "main" org.lwjgl.opengl.OpenGLException: ...
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31 views

Strange result, when changing variable name

I have no idea, what is going on. The mat4 xxx is the cause. Renaming it to "bones"/"bone_transfromations" etc. won't work it gives me an error. Renaming it to "test" works perfectly fine... This is ...
3
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1answer
198 views

What are the advantages of tangent space shading/lighting, and what about attenuation?

In several topics here it was suggested by people that doing lighting in tangent space is better than doing it in world space. Right now I am doing it in camera space, but it's really similar to world ...