• Advertisement
  • Popular Tags

  • Popular Now

  • Advertisement
  • Similar Content

    • 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
  • Advertisement
  • Advertisement
Sign in to follow this  

OpenGL Shader Permutations

This topic is 558 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Hi there,

 

So I have been building a material / shader system which will allow me to compile permutations depending on a shaders options.

 

When you create a material, you provide it with:

  • A Shader Path
  • A list of defines that it uses
  • A list of passes 
  • texture paths
  • Material specific uniforms
  • State (backface culling)
  • Custom flags

 

Now when rendering, I get a bitmask for the options defined in the material; to get the premutation that supports the materials features.

 

This all works pretty well, but I am having some issues with Uniforms (where to add them etc)...

 

 

How do you guys handle uniforms when supporting multiple permutations of a shader?

 

Do you store the uniform locations for each permutation? Or some other method I haven't thought of?

 

 

 

(Using OpenGL 3.3+ as the basis

but will be adding support for 4.5 to get access to compute etc in the future)

 

 

Also if anyone knows of a good implementation that I could look at (for additional ideas), please let me know :)

 

 

Thanks 

Edited by nickyc95

Share this post


Link to post
Share on other sites
Advertisement

If you care that much about performance then maybe it is easier to learn descriptor sets in Vulkan that should be closer to what I tried in DirectX. Each individual uniform takes a lot of time to upload separatelly but if you pack them together in groups with correct alignment for the GPU then not using all of them is okay because it is not a lot of data. If they are not aligned then you can have memory corruption which is why the OpenGL way is said to be easier.

Share this post


Link to post
Share on other sites

If you care that much about performance then maybe it is easier to learn descriptor sets in Vulkan that should be closer to what I tried in DirectX. Each individual uniform takes a lot of time to upload separatelly but if you pack them together in groups with correct alignment for the GPU then not using all of them is okay because it is not a lot of data. If they are not aligned then you can have memory corruption which is why the OpenGL way is said to be easier.

 

Isn't this basically UBOs (Uniform buffers)? Which I could use if I moved up to 4.5

 

The thing that I am trying to find out is, what is the best way to associate these uniforms (whether they be single uniforms or packed ubos) with a specific instance of a shader / a shader permutation

 

Thanks 

Share this post


Link to post
Share on other sites

I have not tried OpenGL 4.5 yet but if you go with uniform buffers or descriptor sets then you will probably apply the same principles as DirectX has used for a long time.

Large things like light sources do not have to change too often so we keep them in a buffer that rarely has to update.

Then you have data associated with instances in one buffer and another buffer for each material if you have the time left for the most frequently changed settings.

 

* A set of variables that update once per frame/pass.

    Light sources[]

    Camera settings

    Fog color

* A set of variables that update once per instance

    Transform

    Color

* A set of variables that update once per material within the instance (optional)

    Specular

    Gloss

 

If something like bone data takes extra space then additional buffers can be used only when needed.

Edited by Dawoodoz

Share this post


Link to post
Share on other sites

I have not tried OpenGL 4.5 yet but if you go with uniform buffers or descriptor sets then you will probably apply the same principles as DirectX has used for a long time.

Large things like light sources do not have to change too often so we keep them in a buffer that rarely has to update.

Then you have data associated with instances in one buffer and another buffer for each material if you have the time left for the most frequently changed settings.

 

* A set of variables that update once per frame/pass.

    Light sources[]

    Camera settings

    Fog color

* A set of variables that update once per instance

    Transform

    Color

* A set of variables that update once per material within the instance (optional)

    Specular

    Gloss

 

If something like bone data takes extra space then additional buffers can be used only when needed.

Yeah I get that,

 

but do you associate a buffer PER SHADER INSTANCE?

Share this post


Link to post
Share on other sites

Then you would not be able to reuse the same shader with multiple materials, if I understand correct this time.

 

So how would I get around this?

 

 

Thanks for input btw :)

Share this post


Link to post
Share on other sites

Just ignore that arguments are given to the shaders in OpenGL. That is a poor legacy design just like the coupling of textures and sampler states that got stuck from old hardware refusing to be compabile with DirectX. Upload the per instance uniforms each time to make sure that no garbage is left from the previous use or you might get highly unpredictable behaviour that is very hard to debug because of the global state causing flickering colors.

 

If you have a lot of data to share between shaders and performance is no problem then you can also upload a texture in advance encoded with general information. I made a text editor by storing character codes in a texture and rendering them using a font atlas.

Generating lots of alternative shaders can be messy if you don't have dynamic shader linking but if it is only for enabling/disabling normal mapping and such then consider making your own GLSL precompiler or simply a function taking boolean feature flags and returning a shader string since the shader compiler in OpenGL is highly unpredictable on different graphics drivers. For example, the token concatunation operand ## is sometimes not available on certain phone models. Integer math operations may sometimes generate random noise.

Some engines even have their own shading languages but that is overkill when you can now use Spir-V and get consistent offline compilation for Vulkan instead of guessing what works everywhere.

Share this post


Link to post
Share on other sites

Just ignore that arguments are given to the shaders in OpenGL

 

How can you do this?

 

When you add the uniforms to the shader you have to specify a shader program 

Share this post


Link to post
Share on other sites

There is not much you can do with an old OpenGL version so you should really consider upgrading for both performance and sanity.

As an ugly and slow workaround, you can wrap the shader into a class and let the class insert what the shader needs from all the data but the dynamic call overhead from using class inheritance will stall the branching predictions for out of order execution. Class objects will also ruin cache locality and load lots of cache lines with garbage even if you have an arena allocator. Even a static function call to a getter or setter will usually fail to inline and generate 16 assembly instructions of bloat just to set up all the registers and then perform the one instruction that you actually wanted to do. The API overhead for redundant safety checks when not using pipeline objects in Vulkan adds more wasted time in your render loop.

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement