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    • By racarate
      Hey everybody!
      I am trying to replicate all these cool on-screen debug visuals I see in all the SIGGRAPH and GDC talks, but I really don't know where to start.  The only resource I know of is almost 16 years old:
      http://number-none.com/product/Interactive Profiling, Part 1/index.html
      Does anybody have a more up-to-date reference?  Do people use minimal UI libraries like Dear ImgGui?  Also, If I am profiling OpenGL ES 3.0 (which doesn't have timer queries) is there really anything I can do to measure performance GPU-wise?  Or should I just chart CPU-side frame time?  I feel like this is something people re-invent for every game there has gotta be a tutorial out there... right?
    • By Achivai
      Hey, I am semi-new to 3d-programming and I've hit a snag. I have one object, let's call it Object A. This object has a long int array of 3d xyz-positions stored in it's vbo as an instanced attribute. I am using these numbers to instance object A a couple of thousand times. So far so good. 
      Now I've hit a point where I want to remove one of these instances of object A while the game is running, but I'm not quite sure how to go about it. At first my thought was to update the instanced attribute of Object A and change the positions to some dummy number that I could catch in the vertex shader and then decide there whether to draw the instance of Object A or not, but I think that would be expensive to do while the game is running, considering that it might have to be done several times every frame in some cases. 
      I'm not sure how to proceed, anyone have any tips?
    • By fleissi
      Hey guys!

      I'm new here and I recently started developing my own rendering engine. It's open source, based on OpenGL/DirectX and C++.
      The full source code is hosted on github:

      I would appreciate if people with experience in game development / engine desgin could take a look at my source code. I'm looking for honest, constructive criticism on how to improve the engine.
      I'm currently writing my master's thesis in computer science and in the recent year I've gone through all the basics about graphics programming, learned DirectX and OpenGL, read some articles on Nvidia GPU Gems, read books and integrated some of this stuff step by step into the engine.

      I know about the basics, but I feel like there is some missing link that I didn't get yet to merge all those little pieces together.

      Features I have so far:
      - Dynamic shader generation based on material properties
      - Dynamic sorting of meshes to be renderd based on shader and material
      - Rendering large amounts of static meshes
      - Hierarchical culling (detail + view frustum)
      - Limited support for dynamic (i.e. moving) meshes
      - Normal, Parallax and Relief Mapping implementations
      - Wind animations based on vertex displacement
      - A very basic integration of the Bullet physics engine
      - Procedural Grass generation
      - Some post processing effects (Depth of Field, Light Volumes, Screen Space Reflections, God Rays)
      - Caching mechanisms for textures, shaders, materials and meshes

      Features I would like to have:
      - Global illumination methods
      - Scalable physics
      - Occlusion culling
      - A nice procedural terrain generator
      - Scripting
      - Level Editing
      - Sound system
      - Optimization techniques

      Books I have so far:
      - Real-Time Rendering Third Edition
      - 3D Game Programming with DirectX 11
      - Vulkan Cookbook (not started yet)

      I hope you guys can take a look at my source code and if you're really motivated, feel free to contribute :-)
      There are some videos on youtube that demonstrate some of the features:
      Procedural grass on the GPU
      Procedural Terrain Engine
      Quadtree detail and view frustum culling

      The long term goal is to turn this into a commercial game engine. I'm aware that this is a very ambitious goal, but I'm sure it's possible if you work hard for it.


    • By tj8146
      I have attached my project in a .zip file if you wish to run it for yourself.
      I am making a simple 2d top-down game and I am trying to run my code to see if my window creation is working and to see if my timer is also working with it. Every time I run it though I get errors. And when I fix those errors, more come, then the same errors keep appearing. I end up just going round in circles.  Is there anyone who could help with this? 
      Errors when I build my code:
      1>Renderer.cpp 1>c:\users\documents\opengl\game\game\renderer.h(15): error C2039: 'string': is not a member of 'std' 1>c:\program files (x86)\windows kits\10\include\10.0.16299.0\ucrt\stddef.h(18): note: see declaration of 'std' 1>c:\users\documents\opengl\game\game\renderer.h(15): error C2061: syntax error: identifier 'string' 1>c:\users\documents\opengl\game\game\renderer.cpp(28): error C2511: 'bool Game::Rendering::initialize(int,int,bool,std::string)': overloaded member function not found in 'Game::Rendering' 1>c:\users\documents\opengl\game\game\renderer.h(9): note: see declaration of 'Game::Rendering' 1>c:\users\documents\opengl\game\game\renderer.cpp(35): error C2597: illegal reference to non-static member 'Game::Rendering::window' 1>c:\users\documents\opengl\game\game\renderer.cpp(36): error C2597: illegal reference to non-static member 'Game::Rendering::window' 1>c:\users\documents\opengl\game\game\renderer.cpp(43): error C2597: illegal reference to non-static member 'Game::Rendering::window' 1>Done building project "Game.vcxproj" -- FAILED. ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========  
      #include <GL/glew.h> #include <GLFW/glfw3.h> #include "Renderer.h" #include "Timer.h" #include <iostream> namespace Game { GLFWwindow* window; /* Initialize the library */ Rendering::Rendering() { mClock = new Clock; } Rendering::~Rendering() { shutdown(); } bool Rendering::initialize(uint width, uint height, bool fullscreen, std::string window_title) { if (!glfwInit()) { return -1; } /* Create a windowed mode window and its OpenGL context */ window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL); if (!window) { glfwTerminate(); return -1; } /* Make the window's context current */ glfwMakeContextCurrent(window); glViewport(0, 0, (GLsizei)width, (GLsizei)height); glOrtho(0, (GLsizei)width, (GLsizei)height, 0, 1, -1); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glfwSwapInterval(1); glEnable(GL_SMOOTH); glEnable(GL_DEPTH_TEST); glEnable(GL_BLEND); glDepthFunc(GL_LEQUAL); glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); glEnable(GL_TEXTURE_2D); glLoadIdentity(); return true; } bool Rendering::render() { /* Loop until the user closes the window */ if (!glfwWindowShouldClose(window)) return false; /* Render here */ mClock->reset(); glfwPollEvents(); if (mClock->step()) { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glfwSwapBuffers(window); mClock->update(); } return true; } void Rendering::shutdown() { glfwDestroyWindow(window); glfwTerminate(); } GLFWwindow* Rendering::getCurrentWindow() { return window; } } Renderer.h
      #pragma once namespace Game { class Clock; class Rendering { public: Rendering(); ~Rendering(); bool initialize(uint width, uint height, bool fullscreen, std::string window_title = "Rendering window"); void shutdown(); bool render(); GLFWwindow* getCurrentWindow(); private: GLFWwindow * window; Clock* mClock; }; } Timer.cpp
      #include <GL/glew.h> #include <GLFW/glfw3.h> #include <time.h> #include "Timer.h" namespace Game { Clock::Clock() : mTicksPerSecond(50), mSkipTics(1000 / mTicksPerSecond), mMaxFrameSkip(10), mLoops(0) { mLastTick = tick(); } Clock::~Clock() { } bool Clock::step() { if (tick() > mLastTick && mLoops < mMaxFrameSkip) return true; return false; } void Clock::reset() { mLoops = 0; } void Clock::update() { mLastTick += mSkipTics; mLoops++; } clock_t Clock::tick() { return clock(); } } TImer.h
      #pragma once #include "Common.h" namespace Game { class Clock { public: Clock(); ~Clock(); void update(); bool step(); void reset(); clock_t tick(); private: uint mTicksPerSecond; ufloat mSkipTics; uint mMaxFrameSkip; uint mLoops; uint mLastTick; }; } Common.h
      #pragma once #include <cstdio> #include <cstdlib> #include <ctime> #include <cstring> #include <cmath> #include <iostream> namespace Game { typedef unsigned char uchar; typedef unsigned short ushort; typedef unsigned int uint; typedef unsigned long ulong; typedef float ufloat; }  
    • By lxjk
      Hi guys,
      There are many ways to do light culling in tile-based shading. I've been playing with this idea for a while, and just want to throw it out there.
      Because tile frustums are general small compared to light radius, I tried using cone test to reduce false positives introduced by commonly used sphere-frustum test.
      On top of that, I use distance to camera rather than depth for near/far test (aka. sliced by spheres).
      This method can be naturally extended to clustered light culling as well.
      The following image shows the general ideas

      Performance-wise I get around 15% improvement over sphere-frustum test. You can also see how a single light performs as the following: from left to right (1) standard rendering of a point light; then tiles passed the test of (2) sphere-frustum test; (3) cone test; (4) spherical-sliced cone test

      I put the details in my blog post (https://lxjk.github.io/2018/03/25/Improve-Tile-based-Light-Culling-with-Spherical-sliced-Cone.html), GLSL source code included!
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OpenGL OpenGL for Linux and MacOSX?

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Hello OpenGL gurus,

I’ve been developing with OpenGL exclusively on Windows for several years now and I’m entering the cross-platform compiling world.

So far, I use skaslev-gl3w https://github.com/skaslev/gl3w to generate gl3w.h, gl3.h and gl3w.c. I found OpenGL32.lib within Visual Studio… it’s a wonderful world indeed… but when compiling with g++ on Linux, gl3w.c is requesting glx.h… and cough at glXGetProcAddress... Oups! There is no trace of this file on opengl.org and Googling on this topic is rather confusing so I decide to ask here.

1 - Why GLX? I thought pure GL was king on Linux... I'm confuse! (I surely dont want to rewrite my code)

2 - Where to find the official OpenGL package to develop on Linux and MacOSX?

Thx Edited by Neosettler

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I can't answer about MaC OS X, it's been too many years for me. Linux isn't an OS so there's no definitive answer there, but I can tell you about Debian-derived OSes (like Ubuntu), which are GNU-based OSes that can sometimes use the Linux kernel: try installing the libgl1-mesa-dev package. If you're asking about Android, another common OS that uses the Linux kernel, the GLES libraries should come with your devkit.

The answer to why your third-party software (skaslev-gl3w) uses GLX, well, you'd have to ask whoever developed it, but it's a handy and standard way to create a GL context on an X11 server.

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Thank you Bregma,

Your answer almost gave me a heart attack. For all the porting a need to do, I thought OpenGL would be a breeze.

I’m currently working with CentOS/Redhat and I tried yum install libgl1-mesa-dev but the package is not found. So I’m guessing there’s extra steps to be made.

I simply need a pure OpenGL context 4.x, no extra lib, no fancy stuff, only the core… I’d really appreciate if anyone could help clear this up.

Thx again

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On MacOSX read this about how OpenGL development works there: http://www.geeks3d.com/20121109/overview-of-opengl-support-on-os-x/

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On CentOS/RHEL, you're probably after the mesa-libGL-devel package. :)


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I simply need a pure OpenGL context 4.x, no extra lib, no fancy stuff, only the core… I’d really appreciate if anyone could help clear this up.

Problems is there's not really such as thing as a pure OpenGL context. You're going to need something to draw to.

Even if you're going full screen, you're not directly programming the GPU and you're not driving the video output chips, you need to go through the OS kernel. A typical modern OS kernel is design to prevent you from getting at the hardware directly: you need to ask it nicely at the very least if it will do you the favour of accessing the hardware on your behalf. On a GNU/Linux system, that means getting the X11 server to share nicely. On Mac OS X that means getting the Quartz service to share nicely. Even on Microsoft Windows you need to share nicely with other applications calling into the embedded display service. On Android you use EGL to share the flinger nicely.

There are cross-platform libraries that will get you an OpenGL context. That's what they're for and why they're there. SDL, for example, works very well on all the above platforms. If you insist on doing without such a library, the source is free so you can see how it works and reimplement it yourself. Of course, it might turn out SDL uses glx/wgl/egl underneath, because to do otherwise would reimplement all those ioctl/X11/port/SYS calls. Might be worth checking, though, or even just using the library directly.

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The closest you can get to a "pure" OpenGL rendering context on X11 is by just using the X11 library itself.
Some of the older OpenGL books go into this but unfortunately it is becoming a bit of a lost art in the newer literature.

A good example is http://content.gpwiki.org/index.php/OpenGL:Tutorials:Setting_up_OpenGL_on_X11
As you can see, this uses GLX (which is what provides the rendering context).

Some more typical rendering contexts include...

wxGLWidget (wxWidgets)
QtOpenGL (Qt)
Gtkglext (Gtk)

Personally, even though I am a C++ developer, I still highly recommend Glut. It is really portable and is already installed on most Linux distros. The 100% free implementation is called FreeGlut. Edited by Karsten_

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I use SDL and OpenGL for my game. I found porting my game from windows to Linux was a breeze I didn't even need to edit any code and the computer seemed to have all the files I needed. As far as I know there is no such thing as "pure" OpenGL you will always need some way to window it. I also find using Glew helps but to each his own.

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If you want something portable that gives you only the OpenGL context, and nothing more, then I recommend glfw. Well, it gives you a little more, like interface to I/O (e.g. mouse, keyboard). In my opinion, glfw is a stronger and cleaner library than glut.

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Thank you Bregma,

Your answer almost gave me a heart attack. For all the porting a need to do, I thought OpenGL would be a breeze.

Note though that all these libraries are only for setting up the GL context and getting a window to draw in, and some input (and possibly a few utility functions)

Those of course have to be OS specific.

All the actual rendering is the same standard OpenGL, as long as you use the same profile, so no need for heart attacks :)

(some drivers might have bugs, or allow some invalid behaviour that breaks on other drivers, but that is a separate story... ) Edited by Olof Hedman

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