OpenGL is a graphics standard and API which targets the desktop and workstation markets. It is designed to be easy to accelerate with dedicated computer hardware, and hence most implementations give greatly improved performance over traditional software rendering. Currently, OpenGL is used for ...

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votes
4answers
885 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 ...
6
votes
1answer
168 views

Excluding Background from Color Picking

I've implemented picking based on color coding, but I don't want the background color to be pickable. Is there any way in openGL (2.x) to exclude the background color? For some reason, doing ...
6
votes
1answer
623 views

OpenGL ES object rotation around z axis

I have an object on my screen which is presented rotated and panned, But i have 2 problems regarding the z axis rotations. It's a bit tricky to explain so i uploaded 2 videos to describe each problem. ...
6
votes
1answer
241 views

How to debug framerate drops with VBOs, OpenGL

I'm working on an experimental app to test how VBOs perform when rendering a minecraft-like world. If the performance is better than what I use now I'll update my actual game. Based on what everyone ...
6
votes
3answers
440 views

State of the art Culling and Batching techniques in rendering [closed]

I'm currently working with upgrading and restructuring an OpenGL render engine. The engine is used for visualising large scenes of architectural data (buildings with interior), and the amount of ...
6
votes
1answer
288 views

How to find the bottleneck in a typical OpenGL game?

I am working on a little game engine. All major features are implemented yet, despite game logic which I assume not to be such a computational effort. The framerate is at least around 40 FPS, most of ...
6
votes
1answer
408 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 ...
6
votes
2answers
1k views

Getting the number of fragments which passed the depth test

In "modern" environments, the "NV Occlusion Query" extension provides a method to get the number of fragments which passed the depth test. However, on the iPad / iPhone using OpenGL ES, the extension ...
6
votes
1answer
1k views

How can I get my meshes to work with Bullet Physics?

The problem is that I'm trying to use my meshes with Bullet Physics for the collision part of my game. When I attempted doing this method with my GLM(model loading library by nate robins) model, I ...
6
votes
1answer
2k views

gl_PointCoord always zero

I am trying to draw point sprites in OpenGL with a shader but gl_PointCoord is always zero. Here is my code Setup: //Shader creation..(includes glBindAttribLocation(program, ATTRIB_P, "p");) ...
6
votes
3answers
1k views

Common light map practices

My scene consists of individual meshes. At the moment each mesh has its associated light map texture, I was able to implement the light mapping using these many small textures. 1) Of course, I want ...
6
votes
2answers
761 views

atmospheric scattering and sky geometry

I'm trying to implement an atmospheric scattering in my graphics (game) engine based on the gpu gems article: link. An example implementation from that article uses a skydome. My scene is different - ...
6
votes
0answers
170 views

OpenGL profiling with AMD PerfStudio 2 [closed]

I'm rendering just a really small amount of polygons for my UI but however I still tried to increase the FPS. In the end I removed redundant calls which increased the FPS. I really don't want to lose ...
6
votes
1answer
284 views

Getting started to OpenGL - little question

Im starting to learn opengl, and after 2 days, searching and trying hard, i finally installed all the libraries i need (lol). So, I'm following this tutorial, and it says to use glfwOpenWindowHint ...
5
votes
3answers
864 views

Started game development no idea of computer graphics. Should I learn tools or concepts? [closed]

I am in 6th semester of my Computer science bachelor degree program, Working as Intern in a start up company. I started game development using AndEngine, things are going good because I have good hold ...
5
votes
3answers
5k views

Should I use Game Engines to learn to make 3D games? [closed]

HI i am a software engineering student in his second-last year. I am proficient with C,C++,C# and java programming languages, and being a student of engineering I have studied calculus, vectors etc ...
5
votes
2answers
2k views

What is the order-less rendering technique that allows partial transparency?

I've seen somewhere rendering technique that allows order-less rendering of partially transparent sprites/objects. Though I can't remember what the technique is called, so I'm having trouble Googling ...
5
votes
3answers
401 views

What is the purpose of indices in 3D rendering?

Suppose you were creating a 3D cube in OpenGL. You implement the necessary vertex data for the object (cube). What would be the point of using indices? void CreateCube() { ...
5
votes
2answers
184 views

How to use OpenGL functions from multiples thread?

I'm writing a small game using OpenGL. I'm implementing basic networking in this game and I'm facing a problem. I have a thread in my client socket class that check for available data, when there ...
5
votes
1answer
9k views

Why is Minecraft's default resolution (seemingly) non-standard?

Background: I'm writing some articles on Minecraft in an attempt to introduce 10-year olds to development through modding. I know very little about the game itself, though :) I'm trying to understand ...
5
votes
3answers
609 views

How portable are OpenGL versions, really?

If I write a game engine that uses OpenGL 1.5 (not assuming what else I do), is it portable now and is it still portable five years from now or are/will support for OpenGL by hardware and drivers (be) ...
5
votes
2answers
851 views

Is the “impossible object” possible in computer graphics?

This may be a silly question but I want to know the answer to it. I saw this thing called the "impossible object", while they're many different images of this online, it's suppost to be impossible ...
5
votes
3answers
2k views

OpenGL Vertex Attributes - Normalisation

Alas, I have searched, and have found no definitive answer. When would you normalize the vertex data in OpenGL using the following command: glVertexAttribPointer(index, size, type, normalize, ...
5
votes
1answer
2k views

GLSL Light (Attenuation, Color and intensity) formula

I'm implementing point lights in my Voxel engine, and I'm really struggling to get a good flow of light, from 100% near the light source to 0% at the light radius. I have 5 arguments for the ...
5
votes
2answers
2k views

OpenGL: Is it possible to use VAO's without specifying a VBO

On all the tutorials I can find about VAO's (Vertex Array Objects), they show on how to use them by configuring vertex attributes and binding a VBO (Vertex Buffer Object). But I want to create a VAO ...
5
votes
4answers
4k views

Geometry instancing in OpenGL ES 2.0

I am planning to do geometry instancing in OpenGL ES 2.0 Basically I plan to render the same geometry(a chair) maybe 1000 times in my scene. What is the best way to do this in OpenGL ES 2.0? I am ...
5
votes
5answers
810 views

What are some low-level performance tweaks for iPhone games written in c?

I'm interested in some performance tweaks for a relatively simple OpenGL ES based 2D iPhone game. What performance tweaks have you found? The performance of the game is pretty good on most devices ...
5
votes
3answers
5k views

How can I get started programming OpenGL on Mac OS X?

I'm trying to start OpenGL programming on a Mac, which brings me into unknown territory on a lot of things. During the day, I'm a Web Developer, working in C# and before that in PHP and Delphi, all ...
5
votes
3answers
3k views

Trapping mouse inside window in OpenGL with GLUT?

I perfectly understand that GLUT is limited and the following problem can't probably be solved with OpenGL/GLUT, but since I don't know exactly if it can or not, I better just ask. Maybe I'm doing ...
5
votes
2answers
724 views

3D models on 2D tilemap perspective when scrolling

I am creating a small top-down game, where the player traverses a 2D tilemap, with an illusion of depth provided by 3D models for things like buildings or trees. Having gotten to the point where I ...
5
votes
3answers
8k views

How to draw 2D images using OpenGL, in SDL?

After everything, I managed to find a simple piece of code that shows how to draw a 2D image with openGL: #include "SDL/SDL.h" #include "SDL/SDL_opengl.h" #include "SDL/SDL_image.h" ...
5
votes
2answers
3k views

In OpenGL Can I Discover the Depth Range of a Depth Buffer?

I am doing a GL multi-pass rendering app for iOS. The first pass renders to a depthbuffer texture. The second pass uses the values in the depth buffer to control the application of a fragment shader. ...
5
votes
2answers
736 views

Atmospheric Scattering

I want to add some nice atmospheric scattering to my 3D game engine but I am very concerned with conserving resources. I am not very familiar with how its done but can someone please give me some ...
5
votes
4answers
623 views

Creating a voxel world with 3D arrays using threads

I am making a voxel game (a bit like Minecraft) in C++(11), and I've come across an issue with creating a world efficiently. In my program, I have a World class, which holds a 3D array of Region ...
5
votes
2answers
3k views

Toggle Fullscreen at Runtime

Using the library GLFW, I can create a fullscreen window using this line of code. glfwOpenWindow(Width, Height, 8, 8, 8, 8, 24, 0, GLFW_FULLSCREEN); The line for creating a standard window looks ...
5
votes
2answers
883 views

Disadvantages of using multiple versions of OpenGL in LWJGL?

So, I'm trying to figure out LWJGL, and my goal is to use OpenGL 3.2 (because pretty shaders are pretty). But in every tutorial I can find for LWJGL, they import a bunch of different OpenGL versions ...
5
votes
1answer
358 views

Why would I support multiple rendering engines simultaneously?

I've seen some games from the early 2000s that had a launcher where you could select the rendering engine you wanted to use: DirectX or OpenGL. Maybe I haven't looked hard enough, but I haven't seen ...
5
votes
2answers
2k views

Integrate LibRocket With SDL And OpenGL

I been currently involved in a game project and we reach the point we're want to added the GUI for menus and other stuff but the time that we maybe spent developing our own system could cost us a bit ...
5
votes
2answers
620 views

Which are the most futureproof languages for graphics (shader) programming?

I have written some GLSL and Cg shaders a couple years back. I am starting another graphics engine project and I want to choose my technologies carefully so that my code will be accessible years down ...
5
votes
1answer
706 views

Particle System OpenGL (ortho)

I want to implement a particle system in my game but i have no idea where to start :S I've never programmed a particle system, so this is my first time >.<. I only want to display pixels ...
5
votes
3answers
5k views

Open Source Engine for RTS [closed]

I must write a cross-platform real-time-strategy game within 2-3 months. I want use C++ and OpenGL and am looking for an engine. The engine must be open source and work under both Linux and Windows. ...
5
votes
1answer
489 views

Is a 10 meg 2048x2048 bitmap too big a size texture to use in an OpenGL game?

This is a speed question, I have a texture, which is 2048 per 2048, the texture is designed to run in big resolutions (1920x1080 for example). The problem is, that the texture have a size of 10MB in ...
5
votes
2answers
206 views

Game has noticeable frame drops but when through a profiler it always runs smooth

I'm trying to optimize my PC game but I can find the bottleneck since every time I run it through a profiler (gDEBugger) it runs smooths. When running outside gDEBugger I get these annoying hiccups. ...
5
votes
3answers
13k views

glTranslate, how exactly does it work?

I have some trouble understanding how does glTranslate work. At first I thought it would just simply add values to axis to do the transformation. However then I have created two objects that would ...
5
votes
2answers
780 views

Best way to do buttons for an OpenGL ES iPhone game

I'm making a simple 2d game in OpenGL ES and I want to add movement buttons to it. What's the best way of going about this? In previous projects I've simply added UIButtons to the view but I hear ...
5
votes
2answers
1k views

What is causing these texture edge artifacts on some video cards?

I have a 2d heightfield converted into a very simple mesh and textured with tiles from a texture atlas. The tiles texture is drawn with: glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_CLAMP); ...
5
votes
2answers
1k views

Generating geometry when using VBO

Currently I am working on a project in which I generate geometry based on the players movement. A glorified very long trail, composed of quads. I am doing this by storing a STD::Vector, and removing ...
5
votes
2answers
1k views

3D primitive rendering library

I am looking for a library which would easily allow me to render shapes (cubes, spheres, lines, circles, etc.) in 3D3 and OpenGL if possible. I want to be able to rapidly design visual debugging tools ...
5
votes
1answer
3k views

How to use modern OpenGL for 2D games?

I've found a plethora of "modern" OpenGL (3.0+) tutorials for 3D, but I have found next to nothing when looking for information on how to use it for 2D game development. How can I get started using ...
5
votes
2answers
272 views

Include deprecated OpenGl “immediate mode” context in OpenGl 4?

I'm working on an app that uses immediate mode in all of it's draw routines and I'd like to keep those functions intact when updating our graphics drivers to OpenGl 4. My intention is to get the app ...