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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 Shadow mapping with GLSL

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Hey guys!

 

I'm having some serious trouble implementing shadow mapping in my OpenGL/OpenGL ES application. There are many sources and discussions out there, but they often cover different versions of the API or omit some details. The way I'm doing it is by first constructing an orthographic projection matrix based on a light source. The "frustum" is adjusted to contain a terrain mesh.

 

Vector3 offset = {1.0f, -1.0f, 1.0f}; // Light direction
offset.Normalize();
offset *= 30.0f;
Vector3 center = {15.0f, 0.0f, 15.0f};
Vector3 eye = center - offset;
Vector3 up = {0.0f, 1.0f, 0.0f};
Matrix4 viewMatrix = LookAt(eye, center, up);

Matrix4 projectionMatrix = Ortho(-30.0f, 30.0f, -30.0f, 30.0f, 0.0f, 60.0f); // Depth range is 60.0

Matrix4 shadowMatrix = viewMatrix * projectionMatrix;

 

Then I am drawing all the models that populate the world to the shadow map, and projecting it onto the terrain. It looks great for things that are positioned above ground. The problem emerges when they are not, in which case they are projected just the same. Naturally they should appear in the shadow map, so I am assuming that it is the depth comparison that fails. The shadow map is being rendered directly to a texture (no render buffer involved), with settings GL_RGBA and GL_UNSIGNED_BYTE. The attachment is done through GL_COLOR_ATTACHMENT0, and for the color value I have tried to use a linearized and normalized gl_FragCoord.z, but now I am more inclined to use the same manually projected vertex z that is used in the other render step. The shaders look roughly like this:

 

// Shadow vertex shader
attribute vec4 a_Position;
uniform mat4 u_ShadowMatrix;
uniform mat4 u_WorldMatrix;
varying vec4 v_ShadowCoordinate;
void main()
{
  v_ShadowCoordinate = u_ShadowMatrix * u_WorldMatrix * a_Position;
  gl_Position = v_ShadowCoordinate;
}
 
// Shadow fragment shader
varying vec4 v_ShadowCoordinate;
void main()
{
  gl_FragColor = vec4(v_ShadowCoordinate.z / 60.0); // Without packing
}
 
// Render vertex shader
uniform mat4 u_WorldMatrix;
uniform mat4 u_ViewProjectionMatrix;
uniform mat4 u_ShadowMatrix;
attribute vec4 a_Position;
attribute vec2 a_TextureCoordinate;
varying vec2 v_TextureCoordinate;
varying vec4 v_ShadowCoordinate;
void main()
{
  // I have a suspicion this might mess up the z, but it's vital for the projection
  mat4 shadowBiasMatrix = mat4(
    0.5f, 0.0f, 0.0f, 0.0f,
    0.0f, 0.5f, 0.0f, 0.0f,
    0.0f, 0.0f, 0.5f, 0.0f,
    0.5f, 0.5f, 0.5f, 1.0f);
 
  v_TextureCoordinate = a_TextureCoordinate;
  v_ShadowCoordinate = shadowBiasMatrix * u_ShadowMatrix * u_WorldMatrix * a_Position;
  gl_Position = u_ViewProjectionMatrix * u_WorldMatrix * a_Position;
}
 
// Render fragment shader
uniform sampler2D u_Texture;
uniform sampler2D u_ShadowMap;
varying vec2 v_TextureCoordinate;
varying vec4 v_ShadowCoordinate;
void main()
{
  vec4 textureColor = texture2D(u_Texture, v_TextureCoordinate);
  vec4 shadowMapColor = texture2D(u_ShadowMap, v_ShadowCoordinate.xy);
  if ((shadowMapColor.x * 60.0) < v_ShadowCoordinate.z) // Same projection as in the shadow shader, right?
    shadowMapColor = vec4(vec3(0.5), 1.0);
  else
    shadowMapColor = vec4(1.0); // No shadow
  
  gl_FragColor = textureColor * shadowMapColor;
}
 
I have tried different ways of computing the shadow map, with more elaborate packing methods. Ultimately I am assuming that OpenGL clamps the values between 0.0 and 1.0, or rather 0 and 255 as in the case of my texture format. There has to be a more obvious problem with my implementation. I can mention that changes to the render state such as dither, depth test and face culling doesn't make a noticeable difference. Can anyone think of a possible flaw? Any tips are greatly appreciated.
 
- David
Edited by Vanderry

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I guess I am getting better results from using gl_FragCoord.z in the shadow fragment shader, in which case the problem is how to depth test the fragments. I did at one point pass the target texture into the shader, to write the minimum of the old and new z but that didn't work so well in OpenGL ES...

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The shadow map is being rendered directly to a texture (no render buffer involved), with settings GL_RGBA and GL_UNSIGNED_BYTE.

That would be the first problem. Render shadows to float textures.
 

gl_FragColor = vec4(v_ShadowCoordinate.z / 60.0); // Without packing

You didn’t divide by .w. 60.0 is an arbitrary number—there is no reason to expect that you will get correct results this way.
gl_FragColor = vec4(v_ShadowCoordinate.z / v_ShadowCoordinate.w);
gl_FragColor = vec4(gl_FragCoord.z); // Alternative.
 

 

mat4 shadowBiasMatrix = mat4(
    0.5f, 0.0f, 0.0f, 0.0f,
    0.0f, 0.5f, 0.0f, 0.0f,
    0.0f, 0.0f, 0.5f, 0.0f,
    0.5f, 0.5f, 0.5f, 1.0f);

Shouldn’t this be column-major?
 

v_TextureCoordinate = a_TextureCoordinate;
  v_ShadowCoordinate = shadowBiasMatrix * u_ShadowMatrix * u_WorldMatrix * a_Position;

This should all be moved to the CPU, I’ve never heard of the shadow coordinate being set in the vertex shader (I would have to spend more time than I am willing to think about whether or not it is possible), below this you have magic numbers again—let’s just stop there.


This section needs to be rewritten.
There is plenty of source code here: http://codeflow.org/entries/2013/feb/15/soft-shadow-mapping/#hard-shadow-mapping
And here: http://www.opengl-tutorial.org/intermediate-tutorials/tutorial-16-shadow-mapping/


L. Spiro Edited by L. Spiro

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Vanderry, on 09 Mar 2015 - 8:32 PM, said:
The shadow map is being rendered directly to a texture (no render buffer involved), with settings GL_RGBA and GL_UNSIGNED_BYTE.
That would be the first problem. Render shadows to float textures.

 

Right you are. That takes care of all the packing business.

 


Vanderry, on 09 Mar 2015 - 8:32 PM, said:
gl_FragColor = vec4(v_ShadowCoordinate.z / 60.0); // Without packing
You didn’t divide by .w. 60.0 is an arbitrary number—there is no reason to expect that you will get correct results this way.
gl_FragColor = vec4(v_ShadowCoordinate.z / v_ShadowCoordinate.w);
gl_FragColor = vec4(gl_FragCoord.z); // Alternative.

 

I could see how this would be appropriate when using the depth value calculated by OpenGL, to linearize it if my understanding is correct. I have been assuming that a manual transformation wouldn't suffer the same "skewing". After all, if I performed the same calculation in C++, then the results should be linear, and w would remain 1.0. The 60.0, or view depth, was a desperate attempt to contain the result within the 0.0-1.0 range. I would use a uniform in practice. With the many opportunities for error here, please don't hesitate to correct me.

 


Vanderry, on 09 Mar 2015 - 8:32 PM, said:
mat4 shadowBiasMatrix = mat4(
    0.5f, 0.0f, 0.0f, 0.0f,
    0.0f, 0.5f, 0.0f, 0.0f,
    0.0f, 0.0f, 0.5f, 0.0f,
    0.5f, 0.5f, 0.5f, 1.0f);
Shouldn’t this be column-major?

 

My math support classes are assuming row-majority. It would have been a good catch if this wasn't the case.

 


Vanderry, on 09 Mar 2015 - 8:32 PM, said:
v_TextureCoordinate = a_TextureCoordinate;
  v_ShadowCoordinate = shadowBiasMatrix * u_ShadowMatrix * u_WorldMatrix * a_Position;
This should all be moved to the CPU, I’ve never heard of the shadow coordinate being set in the vertex shader (I would have to spend more time than I am willing to think about whether or not it is possible), below this you have magic numbers again—let’s just stop there.

 

Isn't the purpose of varying variables to let OpenGL generate fragment-adjusted values across faces? It certainly seems to work, but I may just be doing a whole lot of overcalulation if my assumption is wrong.

 

Thank you very much for taking the time to read this mess :)

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Since it is already back from the dead…

Isn't the purpose of varying variables to let OpenGL generate fragment-adjusted values across faces?

That’s not what I meant. These matrices (included in my previous quote) should all be concatenated on the CPU side and only the final matrix sent to the shader. There are only very rare cases where it is justified to combine matrices in a shader.


L. Spiro

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