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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:
      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
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OpenGL Rule of thumb for VAO & VBO usage?

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I've had a Google around for this but haven't yet found some solid advice. There is a lot of "it depends", but I'm not sure on what.

My question is what's a good rule of thumb to follow when it comes to creating/using VBOs & VAOs? As in, when should I use multiple or when should I not? My understanding so far is that if I need a new VBO, then I need a new VAO. So when it comes to rendering multiple objects I can either:

* make lots of VAO/VBO pairs and flip through them to render different objects, or

* make one big VBO and jump around its memory to render different objects. 

I also understand that if I need to render objects with different vertex attributes, then a new VAO is necessary in this case.

If that "it depends" really is quite variable, what's best for a beginner with OpenGL, assuming that better approaches can be learnt later with better understanding?

 

Edited by Defend

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I've seen comments about storing all UI vertex data in one big VBO. This is unnecessary since you can just store 4 vertices that form a 1 by 1 rectangle, and then translate and scale it to the correct position and dimensions. You can also use this VBO with only 4 vertices for billboards, and particle effects (assuming you don't use a point sprite instead). This will save space on the GPU, but sending data from the CPU (after translating and scaling it) to the shader on the GPU will slow the game down. So, it may be more efficient to store all billboards, and particle effects combined together in one separate VAO & VBO.

As far as I know one huge buffer is slower to work with than multiple smaller buffers that equal the same size as the huge one, you probably won't have to worry about this if each model (not just a rectangle, but a complex model) is stored in its own VAO & VBO.

A short summary: It depends on how much data you store in the buffer, and what you're going to do with it, and the game's performance. Also any like models can use the same VAO & VBO, just translate it to the correct position. For example: boxes or a few chests scattered around a room or an area. Also, if your environment is not too huge you can combine static environment models into one VBO. I would only do this for small areas not an open world.

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10 hours ago, Yxjmir said:

I've seen comments about storing all UI vertex data in one big VBO. This is unnecessary since you can just store 4 vertices that form a 1 by 1 rectangle, and then translate and scale it to the correct position and dimensions.

Streaming data into a VBO from the CPU is very cheap - each map/unmap/draw has a coat, but writing the actual data is very cheap (100k verts a frame shouldn't break a sweat - but 100k draw calls of one quad each is impossibly slow). 

If you translate and scale it using a matrix, then the translation/scale data will be bigger than the extra vertices that you saved. If you tightly pack the translation/scale data in a uniform it will be smaller, but setting a uniform value is extremely expensive compared to writing a few extra vertices to a mapped buffer. Not to mention that sending that data via uniforms would mean that you're performing one draw call per quad instead of one draw call for the entire UI. 

The modern way to avoid those extra vertices is to fill a VBO with the per-quad data (position, size, uv area) - one entry per-quad instead of 4 vertices. Then bind the VBO to your shader as a TBO instead of using the VAO to bind it. In the vertex shader you can then read from the buffer manually using offset 'gl_VertexID / 4' (aka id>>2) to get the per-quad data, and then use 'gl_VertexID % 4' (aka id&3) to determine which corner is being processed / whether to offset positively or negatively by half the size. 

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3 hours ago, Hodgman said:

Streaming data into a VBO from the CPU is very cheap - each map/unmap/draw has a coat, but writing the actual data is very cheap (100k verts a frame shouldn't break a sweat - but 100k draw calls of one quad each is impossibly slow). 

If you translate and scale it using a matrix, then the translation/scale data will be bigger than the extra vertices that you saved. If you tightly pack the translation/scale data in a uniform it will be smaller, but setting a uniform value is extremely expensive compared to writing a few extra vertices to a mapped buffer. Not to mention that sending that data via uniforms would mean that you're performing one draw call per quad instead of one draw call for the entire UI. 

The modern way to avoid those extra vertices is to fill a VBO with the per-quad data (position, size, uv area) - one entry per-quad instead of 4 vertices. Then bind the VBO to your shader as a TBO instead of using the VAO to bind it. In the vertex shader you can then read from the buffer manually using offset 'gl_VertexID / 4' (aka id>>2) to get the per-quad data, and then use 'gl_VertexID % 4' (aka id&3) to determine which corner is being processed / whether to offset positively or negatively by half the size. 

So, lets say we had a scene with several boxes, and chests, and maybe other static objects, was I right that it would be better to store all of that (environment included) in one VBO? Also, is there an max size that a VBO can be, or is it just the maximum number of vertices your card can support?

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51 minutes ago, Yxjmir said:

So, lets say we had a scene with several boxes, and chests, and maybe other static objects, was I right that it would be better to store all of that (environment included) in one VBO? Also, is there an max size that a VBO can be, or is it just the maximum number of vertices your card can support?

Probably -- putting it in the same VBO means you can (potentially) draw it all in a single draw-call, which means there's less CPU overhead (less calls to GL functions) and the GPU will be happy (lots of parallel work to do in one big batch). To achieve this you've also got to merge all your materials into a single UBO/etc, bind all the textures at once, etc... Texture arrays can help for this, and you can put material data into a TBO instead of a UBO, or just arrays inside an UBO and index them.

There is a max size and a way to query it in GL (I forget how exactly :o ). On ancient cards the limit might be a few megabytes, and on modern cards the limit will be a few gigabytes.

If you do need multiple draw-calls, you can still use one VBO though -- draw functions take an offset parameter which specifies where to start reading from the VBO. You can put one model at the start of the VBO and another in the middle. Then you can draw them both without having to change VBO/VAO bindings in between.

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