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    • 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:
      https://github.com/fleissna/flyEngine

      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.

      Bye,

      Phil
    • 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 ==========  
       
      Renderer.cpp
      #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; }  
      Game.zip
    • 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!
       
      Eric
    • By Fadey Duh
      Good evening everyone!

      I was wondering if there is something equivalent of  GL_NV_blend_equation_advanced for AMD?
      Basically I'm trying to find more compatible version of it.

      Thank you!
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OpenGL Ensuring proper cleanup of GPU memory in OpenGL

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I am wondering what are some good  strategies to make sure I am definitely cleaning up all my GPU allocated memory when I exit a level. I plan to allocate/de-allocate on a per-level basis. I am using the OpenGL 4.x C++ API. 

My thought was maybe:

1.  measure GPU memory,
2. instantiate a level, then delete it
3. measure GPU memory again and verify that its the same amount.

I am not sure if functions exist to even accurately measure GPU memory used by a process.. I see there are some functions that I could use on my NVidia card, such as the one mentioned here: http://www.geeks3d.com/20100531/programming-tips-how-to-know-the-graphics-memory-size-and-usage-in-opengl/ 
but I think that only operates at the Kilobyte level...

Alternatively, I believe all the GPU memory allocated for my level will be local to my GL Context. So maybe I could delete and re-create the context, but I'd have to do this through SDL and wonder if this would be practical, or good practice to do between levels.

Suggestions and advice are appreciated!

 

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It looks like, in theory, I could use:

    SDL_GL_DeleteContext(mainGLContext);
    mainGLContext = SDL_GL_CreateContext(mainWindow);

Between levels... not sure how common this approach would be...

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Assuming that your code is correct and doesn't leak, this will have no benefit and only make your loading screens take longer.

I wrap up every GL function that allocates memory and convert them into my own handles. I can then place these handles into an internal list to keep track of active allocations. Whenever I call a GL function that deletes memory I assert that a matching handle is present in my list and then remove it.

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Keep a list of all GL objects allocated for you level, during your level transitions delete all objects from that list - simple as.

How to verify that it actually has been deleted?  You can't and you probably shouldn't worry about it.

A GL implementation may have it's own memory management strategies, and deleting a GL object (via a glDelete* call) is only guaranteed to make the object name available for immediate re-use.

If you want absolute control over memory then use Vulkan.  Otherwise this is something that nobody worries about in GL.

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It looks like, in theory, I could use:

    SDL_GL_DeleteContext(mainGLContext);
    mainGLContext = SDL_GL_CreateContext(mainWindow);

Between levels... not sure how common this approach would be...

No! ... just ... no ...

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It looks like, in theory, I could use:

SDL_GL_DeleteContext(mainGLContext);    mainGLContext = SDL_GL_CreateContext(mainWindow);
Between levels... not sure how common this approach would be...
Destroying and recreating the context is as much of a heavyweight operation as can be, only topped by rebooting the computer. I wouldn't advise doing that.

Keeping track of what objects exist is no magic (in fact, in a correct program it's pretty much a prerequisite that you know, not just about GL objects), so deleting what you no longer need shouldn't really be magic either. There is no verifying that your stuff has been deleted, and no reason why you should need that.
GL does an awful lot of management (and abstraction) for you, and while that's sometimes annoying when you want the bleeding edge, the good thing is that it frees you from worrying about such nitpicks. It also means for example that in the worst case you can just call exit(0) when your game exits. While morally wrong, this will work just fine with OpenGL, the driver will clean up behind you. Try doing that with Vulkan, good luck (on my machine, you do this a couple of times, then the display driver crashes).

So... deleting an object doesn't guarantee that the memory is freed, that's right. Just forget about it. It's somebody else's problem to make it work!

measure GPU memory

OpenGL deliberately doesn't let you do that (though some IHVs have extensions for that). You shouldn't know, nor want to know, how much GPU memory is free. Again, that's both a blessing and a curse, it depends on the situation. Measuring twice and making sure the amount of free memory is the same won't work anyway. That's almost guaranteed to fail.

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On the original question, I think that if you capture a frame in Renderdoc with the "ref all initials" option ticked (or something like that), then it will let you view a full list of textures/buffers.
You could capture a frame before loading a level and after quitting that level, and then manually verify these lists are the same in both captures.

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Thank you all for your input!

On the original question, I think that if you capture a frame in Renderdoc with the "ref all initials" option ticked (or something like that), then it will let you view a full list of textures/buffers.
You could capture a frame before loading a level and after quitting that level, and then manually verify these lists are the same in both captures.

 

Yes! Ideas like this are what I'm looking for. On my engine, I have been lazy about memory management on both GPU and CPU (hence a similar post on the general programming forum for C++ cleanup) and I'm paying the price for it now. Trying to make sure I have all my cleanup in place, and looking for a way to check that I have been thorough.. 

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