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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 Shaking object on near object

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I am writing a space model program when i go near the same object in space, the same objects shake when i rotate the view. but when i move far away from it, it looks okay again. someone told me that it is related to the z buffer precision in opengl. am i right? and how can i solve it?thx

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It might be a precision issue, but I'm not sure it's the precision of the depth buffer.

Where is your object located?
How is your projection set up?
How do you calculate and set the transformations?

Some code (and maybe some screenies) would really be helpful.

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Quote:
Original post by Lord_Evil
It might be a precision issue, but I'm not sure it's the precision of the depth buffer.

Where is your object located?
How is your projection set up?
How do you calculate and set the transformations?

Some code (and maybe some screenies) would really be helpful.

I am drawing a very big city.
when i look from the sky ,there is no problem.
but when i go inside the house, which has some furniture,
the furniture shakes.
On the other hand, i also want to see the environment through the windows of the house , so i can not just draw the house when i am inside it.


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Well, it could be a precision issue with the coordinates that isn't noticable from far distances. Where are the furniture located (coordinates)?

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Quote:
Original post by Lord_Evil
Well, it could be a precision issue with the coordinates that isn't noticable from far distances. Where are the furniture located (coordinates)?

so close to eye and with small difference in their vertex coorindates.

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Yes, close to the eye if you move the camera next to them. That's why depth precision almost can't be the problem.

But what are the absolute coordinates? If the coordinates are very far from the origin, floating point precision in the vector/matrix math might be the issue.

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Quote:
Original post by Lord_Evil
Yes, close to the eye if you move the camera next to them. That's why depth precision almost can't be the problem.

But what are the absolute coordinates? If the coordinates are very far from the origin, floating point precision in the vector/matrix math might be the issue.


yes. the coordinate was very large, becuase it is the real coordinates (around 8000000) ,but with tiny difference between the furniture in coordinates (~0.001-0.0000001).
Someone told me that this make the z buffer has a very large range( due to the very far object and very near object), together with the small differnece between the furnitures in coordinates , opengl will have some precision error on the obj coordinates. So how can i solve it?

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No, that isn't a problem with the z-buffer.

The depth resembles the distance of a fragment to the camera, so if you are close to the objects depth precision is generally good enough.

The z-buffer distributes depth values non-linearly between the near plane (close to the viewer) and the far plane (maximum visible distance to the viewer), with highest precision being close to the viewer. Thus if you view the objects from a large distance you might see z-fighting, which might however be almost not noticable if the objects are small (i.e. have a small on-screen size).

You problem most likely results from lack of floating point precision. Your very large coordinates cause heavy rounding and you might not even be able to distinguish between 800000.0 and 800000.1.

Now, arithmetic operations worsen that problem since small rounding errors add up. This is likely to happen with your transformations.

One possible solution is to use sectors with integer sector coordinates, i.e. the sector at the origin has 0/0/0 and the sectors next to it could have -1/0/0, 1/0/0, ...
Each sector coordinate represents a certain unit, e.g. 1 km or 100m, so the center of the sector with coordinates 2/0/3 might have a distance of x=200m, y=0m and z=300m from the origin.

Objects are now places in relation to a sector, i.e. their coordinate stores the sector coordinate and an offset. For example, if your table is at x=800000.5, y=15.0 and z=4021.7 and a sector coordinate represents 1000 units the table's coordinate would be:
xsector=800, ysector=0, zsector=4 and
xoffset=0.5, yoffset=15, zoffset=21.7

When rendering and transforming you calculate the sector coordinates of the camera and use that as your local origin, i.e. if the camera is located in sector x=799, y=0 and z=4 your table would be rendered at x=(800-799)*1000 + 0.5=1000.5, y=(0-0)*1000 + 15 = 15 and z=(4 - 4) * 1000 + 21.7 = 21.7


Edit: have a look at this thread for some more information, especially the links in the second post.

Edit: another note, just to make it clear: Although I think your problem is not a depth precision one, you should not forget that a high far/near ratio will kill your depth precision anyways. It's not the object coordinates but the settings for the near and far plane of your projection matrix that matter in this case. Near should be as far away as possible (often 1.0 is a good value) whereas far (the maximum viewing distance) should be as near as possible (values between 500 and 1000 should be sufficient). Have a look here.

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