Tagged Questions
0
votes
0answers
80 views
How can I fix dark banding artifacts when I turn on SSAO? [closed]
When enabling SSAO on my object ( in grey on the picture, background in green), sometimes, claimed in position of the camera, dark bands appear on my object (see picture).
The shader is written in ...
1
vote
2answers
95 views
State propagation in modern OpenGL
When last I dabbled in game development, I managed my geometry in a tree. Every node would call the render method on it's children, prior to resetting it's transformations, thus allowing the ...
3
votes
1answer
88 views
Do I need Texture Units when NOT using shaders?
Does calling glActiveTexture() even make sense when not using shaders?
I only have to switch the textures before drawing a buffer with glBindTexture(), right?
3
votes
2answers
229 views
2D water shader similar to Limbo's effect
I'm wondering how I would go about creating a 2D water shader that is seen in this video http://www.youtube.com/watch?v=phChFfi4GOs
The water effect that limbo uses is pretty awesome. I'm not so ...
3
votes
1answer
130 views
variable number of lights in a glsl shader?
I want to render an arbitrary number of lights in my fragment shader. I do not understand how you can properly pass them into the shader though. For example, I want something like this:
uniform int ...
3
votes
1answer
92 views
Multiple Textures in Shader?
I have this (pseudo) code:
unsigned int TextureLoc = glGetUniformLocation(programID, "objectTexture");
for(int i = 0; i < object->texturesCount; i++)
{
glActivateTexture(GL_TEXTURE0);
...
-2
votes
1answer
66 views
Incorrect rotations using openGL GLM and shaders [closed]
The goal of my program is to display a simple colored triangle rotating on the Y axis without any translation. I'm using the GLM library. The problem is that the transformations of my triangle are not ...
3
votes
2answers
138 views
Shaders and Performance
I'm coding my first Shader in my little game engine, and I have some questions about it's performance and common approaches.
Is the Shader code processed by the video card instead of the PC ...
0
votes
1answer
93 views
How to get a smooth dimming with SSAO?
I implemented SSAO in my game based on the tutorial at gamerendering.com. But the results I get are disappointing. Instead of a smooth effect as seen in the nvidia demos, my implementation causes ...
-1
votes
3answers
105 views
Directional light and matrix issues
I'm trying to implement basic directional lightning in OpenGL 3.3 by emulating the logic shown in this guide: http://www.arcsynthesis.org/gltut/Illumination/Tutorial%2009.html
I do not understand ...
0
votes
0answers
49 views
NVIDIA FX Composer 2.5 not updating time in preview
I started testing shaders today and got a problem with
FX Composer.
When I download Shaders from the Shader Library it compiles them fine and
I get a preview which applies the material to the object, ...
1
vote
1answer
103 views
OpenGL VBO Additional Attributes
If I have a buffer with my vertices, normals and texture coordinates, and I use glDrawArrays to draw the VBO to the screen, how can I send attributes per vertex that I placed in an array to the shader ...
0
votes
0answers
96 views
Using OpenGL3.3 and GLSL, texturing is not working [closed]
I am having troubles getting texturing working in my OpenTK/OpenGL 3.3 code. I am sure it is something simple that I am missing, but I just can't seem to get a texture on the square I am rendering. ...
4
votes
1answer
136 views
OpenGL, fetching the names of all uniform blocks in your program
I want to auto-bind uniform blocks with certain named values to certain binding points when I compile a shader. For example, I have some basic, default fixed binding points that are always used for ...
0
votes
1answer
120 views
In OpenGL Shader, Why adding color change vertex position?
I have the following vertex shader:
#version 120
attribute vec4 position;
attribute vec4 acolor;
varying vec4 theColor;
void main(){
gl_Position = position;
//theColor = acolor; //[1]
...
0
votes
1answer
86 views
OpenGL RTT FrameBuffer question and Rendering to texture while sampling it
What i need to do:
Blur the selected texture and pass the texture to another effect for postprocessing.
Notice that i want one texture passed all over.
How do i want to do this:
Bind the FBO ( ...
3
votes
1answer
155 views
How do I render a filled and stroked path using OpenGL?
I want to render a 2-dimensional geometric path consisting of Bézier curves and straight lines. Paths can be concave.
What is the most efficient way to draw this using modern OpenGL? Can I do this ...
16
votes
1answer
389 views
After a succesful glLinkProgram, should I delete / detach my shaders?
After I have a linked program, and thinking about defensive programming, should I delete and detach the shaders used to link this program?
If yes, is that going to free any resources? Or do these ...
1
vote
1answer
236 views
Apply portion of texture atlas
I'm trying to write a shader that only maps a portion of a large texture to my sprite and I'm getting a strange behaviour with my current code.
This is what I have right now:
Texture atlas ...
2
votes
1answer
186 views
VBO and shaders confusion, what's their connection?
Considering OpenGL 2.1 VBOs and 1.20 GLSL shaders:
When creating an entity like "Zombie", is it good to initialize just the VBO buffer with the data once and do N glDrawArrays() calls per each N ...
2
votes
1answer
124 views
Shadow cubemapping?
I am working on a game with C++ and OpenGL 3.2. I have successfully implemented directional shadow maps and now I'd like to upgrade them to shadow cube maps (for point lights). I've done some Googling ...
3
votes
1answer
397 views
How are vertex shader outs sent as inputs to the fragment shader?
I'm learning some OpenGL 3.2 way of doing things and I think it's quite great, I'm actually understanding more of shaders and non-fixed pipeline in 1 week rather than those 2 years I tried to learn ...
12
votes
2answers
333 views
OpenGL: Where shoud I place shaders?
I'm trying to learn OpenGL ES 2.0 and I'm wondering what is the most common practice to "manage" shaders.
I'm asking this question because in the examples I've found (like the one included in the API ...
2
votes
1answer
161 views
How can I pass an array of floats to the fragment shader using textures?
I want to map out a 2D array of depth elements for the fragment shader to use to check depth against to create shadows. I want to be able to copy a float array into the GPU, but using large uniform ...
1
vote
2answers
202 views
Deferred rendering order?
There are some effects for which I must do multi-pass rendering. I've got the basics set up (FBO rendering etc.), but I'm trying to get my head around the most suitable setup. Here's what I'm ...
3
votes
0answers
189 views
Suitability of ground fog using layered alpha quads?
A layered approach would use a series of massive alpha-textured quads arranged parallel to the ground, intersecting all intervening terrain geometry, to provide the illusion of ground fog quite ...
0
votes
0answers
80 views
Opengl binding shaders vs binding buffers performance
Quick question for an opengl guru, I'm in the process of building a render queue and can either reduce the number of shader binding or the number of vertex buffer binding. I just want to know which ...
1
vote
0answers
521 views
ssao implementation
I try to implement a ssao based on this tutorial: link I use a deferred rendering and world coordinates for shading calculations. When saving gbuffer a vertex shader output looks like this:
...
0
votes
2answers
217 views
LWJGL - OpenGL - Texture shading
I want to use LWJGL to create a shader that all it does is change the color of the given texture. For example I tell it to draw the letter A using a sprite sheet then I can tell the shader to draw the ...
11
votes
2answers
359 views
Do I lose/gain performance for discarding pixels even if I don't use depth testing?
When I first searched for discard instruction, I've found experts saying using discard will result in performance drain. They said discarding pixels will break GPU's ability to use zBuffer properly ...
5
votes
2answers
306 views
Geometry shader for multiple primitives
How can I create a geometry shader that can handle multiple primitives? For example when creating a geometry shader for triangles, I define a layout like so:
layout(triangles) in;
...
3
votes
2answers
441 views
Learning OpenGL GLSL - VAO buffer problems?
I've just started digging through OpenGL and GLSL, and now stumbled on something I can't get my head around this one!? I've stepped back to loading a simple cube and using a simple shader on it, but ...
0
votes
1answer
125 views
Artifacts when draw particles with some alpha
I want to draw in my game some particles. But when I draw one particle above another particle, alpha channel from this above "clear" previous drawed particle.
I set in OpenGL blend in this way:
...
2
votes
1answer
164 views
What are the factors that determine the default frequency of a shader call?
After i have been played for some days with various vertex and fragments shaders seems clear to me that this programs are called by the GPU at every and each rendering cycle, the problem is that I ...
12
votes
1answer
735 views
Should I distribute shaders in a compiled form or in plain text?
Having an application that uses shaders that have been wrote in GLSL, what is the best strategy for the distribution in the real world and for the desktop and mobile?
I'm aiming to distribute this in ...
5
votes
1answer
723 views
GLSL, all in one or many shader programs?
I am doing some 3D demos using OpenGL and I noticed that GLSL is somewhat "limited" (or is it just me?). Anyway I have many different types of materials. Some materials have ambient and diffuse color, ...
0
votes
1answer
142 views
Dynamically change shader syntax with the help of C++
I'm starting with the programmable pipeline and the shaders in C++ for OpenGL 3.0+, i would love to be able to change some settings on the fly, for example replacing a function with another function, ...
1
vote
1answer
136 views
Can I limit the number of shader units used by my video card?
Can I limit the number of shader units used by my video card? (A shader unit is the part of the hardware which can execute a shader program, where each unit runs in parallel).
I'm interested in this ...
4
votes
1answer
995 views
Access vertex data stored in VBO in the shader
If I wanted to store extra data in a VBO for skinning (indices for indexing into an array of matrices of bones and floats for applying weights to those bones) How would I go about accessing that data ...
1
vote
2answers
633 views
OpenGL ES high-quality 2D scaling
Let's say I'm making a 2D game and I want to implement a zoom in/out feature. Normally this is as simple as modifying the projection matrix to get more or less of the world to show. However, this ...
1
vote
3answers
207 views
Shaders not linking correctly
I'm writing a rather simple "ShaderManager" which aids me with loading shaders in Open GL, altough I am having a few issues:
The shaders don't link correctly
The the attributes don't bind
Here's ...
1
vote
1answer
919 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
428 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 ...
0
votes
0answers
233 views
Making shaders work for both ATI and NVIDIA in Blender Game Engine
Unfortunately coding OpenGL shaders is more strict for ATI cards. I am trying to get this code from this thread http://blenderartists.org/forum/showthread.php?245954-preethams-sky-impementation-HDR to ...
1
vote
1answer
528 views
How to draw reflection of shaded objects in OpenGL?
I am trying to draw a scene with objects floating around and a mirror among them to reflect the objects in front of it.
I managed to draw the reflection properly when the floating objects aren't ...
3
votes
1answer
1k 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 ...
8
votes
4answers
1k views
Fixed-Function vs Shaders: Which for beginner?
I'm currently going to college for computer science. Although I do plan on utilizing an existing engine at some point to create a small game, my aim right now is towards learning the fundamentals: ...
4
votes
1answer
505 views
Multiplication for MVP matrices: Any benefits to doing so within the vertex shader?
I'd like to understand under what circumstances (if any) it is worth doing MVP matrix multiplication inside a vertex shader.
The vertex shader is run once per vertex, and a single mesh typically ...
4
votes
2answers
815 views
Should the modelview and projection matrices be calculated in the shader or on the CPU?
At minimum I would have a camera with rotation and world position; projections parameters such as angle of view and perspective vs. orthographic; and meshes with scale, angle, and world position.
...
1
vote
1answer
154 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 ...
