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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 VBOs not giving any performance

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Hey everyone... It seems that VBOs are not giving any performance on my pc. It was not woking in my application, so I downloaded the VBO demo from here which has a VBO and a regular vertex array version, but both of them run at the same speed. Has anyone got any idea why isn't VBO faster? My specs: GeForce 6600 AMD64 3000+ 512MB RAM Windows XP SP 2 I tried the same demo on my brother's Radeon X700 and the VBO version ran about 50% faster.

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Performance relative to what? I take it you mean glBegin/glEnd.

VBOs are best used for large amounts of verticies. With few verticies you are unlikely to get much of a performance boost and I think it may even be possible to get a performance loss.

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Quote:
Original post by TGA
Performance relative to what? I take it you mean glBegin/glEnd.

VBOs are best used for large amounts of verticies. With few verticies you are unlikely to get much of a performance boost and I think it may even be possible to get a performance loss.


I mean performance relative with regular Vertex Arrays, and I'm rendering 250.000 triangle to test it...

But I don't think there is a problem in my code, since none of the VBO demos are giving any performance boost, like on other systems... check out the demo in my first post.

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Your computer and your brother's no doubt have different OpenGL implementations. You'll have to read up on your card and see whether or not it supports the VBO extension and actually stores the vertex data on-card, or just simulates them with vertex arrays (caching the vertex data in main memory, then streaming it over each pass).

Since you're getting no performance boost (but your brother is), I doubt your card supports the extension (but his does). There's probably an easy way to check it, but I've no idea how </3

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well... I think a GeForce 6 class video card should have support for VBOs, even if it's not a high end video card right now... the extensenion is obviously present, but the performance is exactly the same as normal vertex arrays, so it might be simulated internally.

It is quite weird...


Is someone else experiencing this on a 6600?

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I use something such as this:

int CheckExtension(char* extensionName)
{
// get the list of supported extensions
char* extensionList = (char*) glGetString(GL_EXTENSIONS);

if (!extensionName || !extensionList)
return 0;

while (*extensionList)
{
// find the length of the first extension substring
unsigned int firstExtensionLength = strcspn(extensionList, " ");


if (strlen(extensionName) == firstExtensionLength &&
strncmp(extensionName, extensionList, firstExtensionLength) == 0)
{
return 1;
}

// move to the next substring
extensionList += firstExtensionLength + 1;
}

return 0;
} // end CheckExtension()


Then call with:

if (!CheckExtension("GL_ARB_vertex_buffer_object"))
MessageBox(NULL, "You don't have VBO Support", "No VBO Support", MB_OK);

Obviously the MessageBox Call is assuming Windows but I'm sure you could write to a file or use OS independent calls.

P.S how do you get nice code scroll windows in my posts? Thanks
[Like this. Edit your post to see how it works. -Yann]

Jamie

[Edited by - Yann L on August 14, 2007 5:02:06 PM]

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Quote:
Original post by jsg007
It is quite weird...

No, it's not. If your test app is not bus-bandwidth bound (highly unlikely with only 250k triangles on a modern PCIe, or even an AGPx8 system), then you won't see the slightest difference between VAs and VBOs. Also, I highly suspect NVidia to cheat a little around the litteral (read: obsolete) wording of the GL specs, and cache VAs onboard. Which for all practical purposes make them equivalent to VBOs in terms of performance.

Never forget that profiling a stream processor (ie. a GPU) is very different than profiling a general purpose CPU. Unless you modify the part of the pipeline that happends to make the current bottleneck of the stream operation chain, you won't see any difference in performance at all. In fact, if you're eg. fragment bound, then immediate mode can be just as fast (or slow) as VBOs.

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r u testing in a small window eg 400x300 (or smaller)

i just tried my game ( which pushes >100k tris frame )
1366x766 VBO=51fps, VA=48fps
400x300 VBO=70fps, VA=58fps (much bigger gap)

preprocessing at 1366x768 on both

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Thanks Yann.

Was a bit weird at first, was shocked when the page loaded to see my code in blocks lol.

I would expect VBO's to be available for your graphics card (mine's really old but it still has it), maybe its a graphics driver thing?

Jamie

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Well, I made my app to be vertex bound, it renders to a small viewport,no texture or fragment program, it loads a model with ~61.000 triangles and renders it 4 times (that's about 250.000 triangles), in 4 different places (so there's no overdraw).

The VA is much faster than the immediate mode, but the VBO runs with the same speed as normal VA, just like in every application I have tested.

I also use the latest driver.

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