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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. 
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    • 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.

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      - Real-Time Rendering Third Edition
      - 3D Game Programming with DirectX 11
      - Vulkan Cookbook (not started yet)

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      Procedural grass on the GPU
      Procedural Terrain Engine
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      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:
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      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 What is a suitable default value for buffers/vertex arrays/textures etc

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I am struggling to choose an appropriate default value to assign for my buffers and so on. For example, I might have a class that has vertex array (unsigned int), what value should I assign by default before it is initialised? 0/-1? Later on I do use these values to check this/these values for sanity checks before using them.

 

Looking at my last and current project I am mostly using 0 but I see a few -1s popping up. Obviously that's not good. Is the first value that the 'Gen' functions will return 1? That seems to be the case as logically if they did return 0 I would notice the effects from that. -1 (unsigned int wrap around) just seems like a value that works purely based on the fact that it ends up being a very large integer that I am probably unlikely to ever have returned from one of these functions. 

 

So what is the 'correct' value I should be using as default values before calling any of these functions:

glGenTextures

glGenBuffers

glGenFramebuffers

glGenVertexArrays

 

I realise I could also use glGetError for validation after calling the functions but I still need a default value and I am now confused what to use.

 

I checked some of the references e.g.

https://www.opengl.org/sdk/docs/man/html/glGenTextures.xhtml

and it doesn't really mention a range for the values returned.

 

Experimentally I am finding that the first value I get is 1 so 0 seems like the best choice, can anyone confirm this?

 

The reason I have gotten confused is glGetUniformLocation as a location of 0 is perfectly valid. What is a good default for that, -1?

 

Thanks.

Edited by Nanoha

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I don't think the glGen* functions can fail, since they don't actually do anything with the GPU.  They simply generate a name, while any allocation happens at bind/upload time.  The reason you can't get 0 back as a name is because 0 is the "name" used to unbind objects.

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Use -1 because object 0 often has very specific meaning in OpenGL, and may give you unexpected behaviour, especially in compatibility contexts.  It's not just for unbinding.

 

Texture object 0 is the "default" texture; in other words it reproduces the behaviour of GL 1.0 before texture objects were added to the core.  You can bind it, you can glTexImage it, you can draw with it.

 

Buffer object 0 disables buffer objects as input and goes back to system/client memory - for certain types of buffer objects.

 

VAO 0 disables VAOs and goes back to GL 2/2.1 style drawing.

 

Program object 0 disables shaders and goes back to the fixed pipeline.

 

Etc.

 

To repeat: binding object 0 often has a very specific meaning that goes beyond just unbinding.  If you bind object 0 you will get behaviour and side-effects, and if you're not aware of that, you'll have some nice debugging sessions ahead of you.

 

Defaulting to -1 will on the other hand give you a nice error if you try to use it, so if you're doing error-checking in your program (you are, aren't you) then you'll more easily catch unintended usage of uninitialized objects.

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Careful with this. There is absolutely zero guarantee in the standard that any of the glGen*() functions won't return the value GLuint(-1) as a valid handle. We've seen drivers that allocate texture handles starting at very high numbers before.

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Careful with this. There is absolutely zero guarantee in the standard that any of the glGen*() functions won't return the value GLuint(-1) as a valid handle. We've seen drivers that allocate texture handles starting at very high numbers before.

 

That is actually true as well.  In fact the only guarantees are (1) a generated name won't be one that is currently in use, and (2) a generated name won't be 0.

 

So with the benefit of this additional information, the only safe thing to do is to remove dependencies on a default/uninitialized state actually mattering.

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Thanks for the responses, given me something to think about.

 

So I guess the only sensible way to do this is perhaps use a flag of some sort rather than rely on using the value as an 'initialized' flag. Most of the time this is ok as I usually need a 'initialize' function to set everything up so returning false should mean that the object doesn't get used anyway but sometimes I do things 'just in time' and create things just before I use them.

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A great many engines just don't actually directly return GL names to the higher-level code.

Nothing in your engine should have any idea it's working with GL other than the low-level renderer. If your Sprite class has a texture, it should have a MyEngine::TextureHandle object, not a GLuint.

Your custom resource handles then can deal with handling uninitialized or failed resources. For instance, you might want all your textures to actually use some specific "default" GL texture if there isn't another texture mapped to it, e.g. some kind of bright and obnoxious pattern. Your high-level logic becomes much simpler as you don't have to constantly check for invalid or null handles, and instead you can just log an error on load failure and then not worry about it.

Buffers are a bit trickier, but the pattern still holds: wrap your buffer handles in a higher-level primitive that protects the users from buffer creation problems. You'll likely get garbled rendering or the like, but it's still probably better than the alternative during development.

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Just allocate texture/buffer/shader/etc handles as and when you need them. They are just handles - you aren't actually performing memory allocation when you create one.

 

Until you actually bind and write to one of these resources, they haven't been allocated.

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I always use zero, it's the only value that says "this is not an allocated name". -1 (0xffffffff) is a valid name that an OpenGL implementation could give at any time.

 

@Boreal Games, I think you're right that in general glGen* functions can't normally fail, but I have had instances where glGen* functions return zero, so it's always worth asserting. IIRC it happened when doing threaded loading on iOS and the OpenGL context I'd created for a thread was in a weird broken state because the system had created/leaked too many OpenGL contexts on prior loads. So it's probably worth an assert after a glGen* call to make sure you're not being given a zero.

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I always use zero, it's the only value that says "this is not an allocated name". -1 (0xffffffff) is a valid name that an OpenGL implementation could give at any time.

 

zero is a valid name for texture objects.

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