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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 opengl proper using of program

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If I have some shader functions to draw single meshes with large number of vertices, some brushes with gradient colors, some particles, should I put these functions in different render passes in a single program or in different programs? will switch programs will do much damage to performce?

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Try to reduce to some minimum or too many programs will hurt your performance.

+ There's a limit to it (Find the constant that defines it).

It would be good to split different effects into different shaders.

If you have similar effects, try to build one shader for all of them. 

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You could also link shaders together after compiling them in modern OpenGL (didnt try it for a version lower thant 4.3). In general shaders can (and propably should) only act on one object at a time. If you have particle system you shouldnt use the same shader for a static mesh.

 

In GL you compile the shader first then attach it to the program, you could use that to build a couple of shaders for the needs of the object rendered with where same kind of objects should use same shader but keep in mind to have only one main per shader type (vertes, fragment and so on). Getting the program object means linking compiled shader assemblies to one single assembly so you even could resolve functions used but not declared in the source.

 

For example

//fragment
#pragma version 450

vec4 colorComponent;
out vec4 Color;

void main()
{
  #ifdef USE_TEXTURE_UNIT_0
  ProcessTextureUnit_0(colorComponent);
  #endif
  #ifdef USE_TEXTURE_UNIT_1
  ProcessTextureUnit_1(colorComponent);
  #endif
  #ifdef USE_TEXTURE_UNIT_2
  ProcessTextureUnit_2(colorComponent);
  #endif
  #ifdef USE_COLOR_COMPONENT
  ProcessColor(colorComponent);
  #endif

  Color = colorComponent;
}

And in your ColorShader have

#pragma version 450

in vec3 BaseColor;

void ProcessColor(inout vec4 colorComponent)
{
  colorComponent =
  {
     colorComponent.x * BaseColor.x,
     colorComponent.y * BaseColor.y,
     colorComponent.z * BaseColor.z,
     colorComponent.w
  };
}

Or you use one single shader with all #ifdef-blocks as done in Unreal Engine 3 and compile justs etting the flags right

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You could also link shaders together after compiling them in modern OpenGL (didnt try it for a version lower thant 4.3). In general shaders can (and propably should) only act on one object at a time. If you have particle system you shouldnt use the same shader for a static mesh.

 

In GL you compile the shader first then attach it to the program, you could use that to build a couple of shaders for the needs of the object rendered with where same kind of objects should use same shader but keep in mind to have only one main per shader type (vertes, fragment and so on). Getting the program object means linking compiled shader assemblies to one single assembly so you even could resolve functions used but not declared in the source.

 

For example

//fragment
#pragma version 450

vec4 colorComponent;
out vec4 Color;

void main()
{
  #ifdef USE_TEXTURE_UNIT_0
  ProcessTextureUnit_0(colorComponent);
  #endif
  #ifdef USE_TEXTURE_UNIT_1
  ProcessTextureUnit_1(colorComponent);
  #endif
  #ifdef USE_TEXTURE_UNIT_2
  ProcessTextureUnit_2(colorComponent);
  #endif
  #ifdef USE_COLOR_COMPONENT
  ProcessColor(colorComponent);
  #endif

  Color = colorComponent;
}

And in your ColorShader have

#pragma version 450

in vec3 BaseColor;

void ProcessColor(inout vec4 colorComponent)
{
  colorComponent =
  {
     colorComponent.x * BaseColor.x,
     colorComponent.y * BaseColor.y,
     colorComponent.z * BaseColor.z,
     colorComponent.w
  };
}

Or you use one single shader with all #ifdef-blocks as done in Unreal Engine 3 and compile justs etting the flags right

sorry for the late reply... :(

but in this way I have to compile many program objects and switch between them during runtime. if so, will it damage performance of thr program?

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The problem isnt compiling many program objects because you first need to take care that you unify your materials. Dont create a new material for an object that uses color and one that dosent but has similar properties and is rendered similar rather than setting a default color value for white for example. There arent that many kinds of rendering normaly like the few standard shaders used in mostly every game (specular, bumped, diffuse and so on) and a few for special advantages like particle system and post processing so there might be not even 100 shader programs you need to compile.

 

When you take the link different kinds of shaders together method then you still have one single program object per shader and also minimize the shader objects created because you compile the code for each shader object only once and link them together in any way to the program object by attaching the handle returned by GL to your created program handle and then call the linker.

 

Performance is lost when switching shaders during render step so you need to build your render pipeline to minimize switching by sorting your objects either by shader and then by texture or vise versa like I described here

 

http://www.gamedev.net/topic/678502-best-way-to-abstract-shaders-in-a-small-engine/#entry5290755

Edited by Shaarigan

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sorry but I still dont get it...I mean if I have a fragment shader subroutine that use a texture and another subroutine that uses only vertex color, how can I merge these two into one in order to minimize states changes? seems impossible to me

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So your problem is more logical or technical?

You know what the #ifdef Tag does in GLSL?

 

I just take the above example as base for this so lets think you have again

//fragment
#pragma version 450

vec4 colorComponent;
out vec4 Color;

void main()
{
  #ifdef USE_TEXTURE_UNIT_0
  ProcessTextureUnit_0(colorComponent);
  #endif
  #ifdef USE_TEXTURE_UNIT_1
  ProcessTextureUnit_1(colorComponent);
  #endif
  #ifdef USE_TEXTURE_UNIT_2
  ProcessTextureUnit_2(colorComponent);
  #endif
  #ifdef USE_COLOR_COMPONENT
  ProcessColor(colorComponent);
  #endif

  Color = colorComponent;
}

as your main Shader linking to the other components and an example component

#pragma version 450

in vec3 BaseColor;

void ProcessColor(inout vec4 colorComponent)
{
  colorComponent =
  {
     colorComponent.x * BaseColor.x,
     colorComponent.y * BaseColor.y,
     colorComponent.z * BaseColor.z,
     colorComponent.w
  };
}

So you want the color fragment shader enabled  then you need to first pass the color shader component to the compiler by call

GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, &ColorComponentSource, 0);
glCompileShader(fragmentShader);

glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &isCompiled);
if(isCompiled == GL_FALSE)
{
  //throw error here
  return;
}

YourShaderManager.StoreComponent(fragmentShader, YOUR_COLOR_SHADER_COMPONENT_ID)

You never discard that shader until your program leaves. After that you pass the compiler flags to glsl and your 'main' shader

GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);

const char* defines = "#define USE_COLOR_COMPONENT 1\n"; //add defines here seperated by \n
const char* sources[2] = { defines, FragmentMainSource };
glShaderSource(fragmentShader, 2, sources, 0);
glCompileShader(fragmentShader);

glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &isCompiled);
if(isCompiled == GL_FALSE)
{
  //throw error here
  return;
}

GLuint program = glCreateProgram();
/**
  Dont forget vertex stuff here ;)
*/
glAttachShader(program, YourShaderManager.GetComponent(YOUR_COLOR_SHADER_COMPONENT_ID));
glAttachShader(program, fragmentShader);

glLinkProgram(program);

(I have not checked this for syntax corectness)

 

and this will result in your fragment shader because the code will look in a way like this to the linker

<colorShader assembly>

in vec3 BaseColor;

void ProcessColor(inout vec4 colorComponent)
{
  colorComponent =
  {
    colorComponent.x * BaseColor.x,
    colorComponent.y * BaseColor.y,
    colorComponent.z * BaseColor.z,
    colorComponent.w
  };
}

<fragmentShader assembly>
#define USE_COLOR_COMPONENT 1

vec4 colorComponent;
out vec4 Color;

void main()
{
  #ifdef USE_TEXTURE_UNIT_0
  <ignored>
  #endif
  #ifdef USE_TEXTURE_UNIT_1
  <ignored>
  #endif
  #ifdef USE_TEXTURE_UNIT_2
  <ignored>
  #endif
  #ifdef USE_COLOR_COMPONENT
  ProcessColor(colorComponent);
  <not defined here but linker will find in previous assembly>
  #endif

  Color = colorComponent;
}

And the program will finaly look like this

in vec3 BaseColor;

void ProcessColor(inout vec4 colorComponent)
{
  colorComponent =
  {
    colorComponent.x * BaseColor.x,
    colorComponent.y * BaseColor.y,
    colorComponent.z * BaseColor.z,
    colorComponent.w
  };
}

vec4 colorComponent;
out vec4 Color;

void main()
{
  ProcessColor(colorComponent);
  Color = colorComponent;
}

Or depending on the optimizer of your GPU vendor

in vec3 BaseColor;
out vec4 Color;

void main()
{
  Color =
  {
    colorComponent.x * BaseColor.x,
    colorComponent.y * BaseColor.y,
    colorComponent.z * BaseColor.z,
    colorComponent.w
  };
}

I hope that will help you

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