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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 glDrawArrays race condition

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Hi everybody, while I think I've already found a working solution for the problem, I still don't really understand why it actually does work. I was hoping somebody could clarify the following for me. I was trying this on an ipod touch (OpenGL ES 1.1). simplified code:
void Foo::drawSome()
{
	GLfloat *vertices = new GLfloat[strLength*12];
	GLfloat	*coordinates = new GLfloat[strLength*18];

	// fill with correct verts and coords...

	// draw stuff
	glPushMatrix();
	
	glTranslatef(x, y, 0.0f);
	
	glBindTexture(GL_TEXTURE_2D, m_fontTex.name);
	glVertexPointer(3, GL_FLOAT, 0, vertices);
	glTexCoordPointer(2, GL_FLOAT, 0, coordinates);
	glDrawArrays(GL_TRIANGLES, 0, strLength*6);
	
	glPopMatrix();

	// here it crashes, basically complaining that I'm freeing memory still in use	
	delete [] vertices;
	delete [] coordinates;
}
The app crashes as soon as I reach a certain amount of verts. Obviously the array are still in use when I try to free the memory. The solution is to use static arrays like this:
void Foo::drawSome()
{
	GLfloat vertices[256*18];
	GLfloat coordinates[256*12];

	// fill with correct verts and coords...

	// draw stuff
	glPushMatrix();
	
	glTranslatef(x, y, 0.0f);
	
	glBindTexture(GL_TEXTURE_2D, m_fooTex.name);
	glVertexPointer(3, GL_FLOAT, 0, vertices);
	glTexCoordPointer(2, GL_FLOAT, 0, coordinates);
	glDrawArrays(GL_TRIANGLES, 0, strLength*6);
	
	glPopMatrix();	
}
I don't understand why this works and dynamically allocated arrays don't. Shouldn't the static arrays be gone as soon as the function returns? So what's the real difference? Does the data on the stack live longer? Long enough for it to work? Please explain...

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When you call gl[Vertex|TexCoord|BlahBlah]Pointer, you're telling the GL that your data is located at that address. OpenGL assumes that the data stays valid indefinitely. In this case, this is not true. The second example (local variables) works through luck - the memory for those variables is located on the stack. The stack remains part of your process's memory space for its whole lifetime, and therefore your program won't crash. However, there's no guarantee that you won't overwrite that data in the next function call.
There are several solutions that I can think of:
1) (Easiest) Call glFinish() before freeing the data. This will ensure that the GL finishes using your data before you free it. This will adversely affect the performance of your application.
2) (Medium) Make your buffers members of your Foo class, allocate them and use them, but don't free them until you're done rendering. You still need to make sure that the GL is finished before you overwrite the data, though.
3) (Harder, but worthwhile). Use VBOs. You can call glBufferData to copy data into the object, or glMapBuffer(GL_ARRAY_BUFFER, GL_WRITE_ONLY) to write directly into it. Then, you render from the VBO, not client memory. Assuming your data doesn't change too often, this will provide the best performance.

If your application crashes after implementing one of these solutions, then either you have a problem elsewhere, or there is a bug in the OpenGL-ES implementation.

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Thanks Graz. So I was indeed just lucky that it works with static arrays. VBOs sound like the right solution for what I need, I'll look into that.


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Quote:
Original post by Graz
When you call gl[Vertex|TexCoord|BlahBlah]Pointer, you're telling the GL that your data is located at that address. OpenGL assumes that the data stays valid indefinitely. In this case, this is not true. The second example (local variables) works through luck - the memory for those variables is located on the stack. The stack remains part of your process's memory space for its whole lifetime, and therefore your program won't crash. However, there's no guarantee that you won't overwrite that data in the next function call.
There are several solutions that I can think of:
1) (Easiest) Call glFinish() before freeing the data. This will ensure that the GL finishes using your data before you free it. This will adversely affect the performance of your application.
2) (Medium) Make your buffers members of your Foo class, allocate them and use them, but don't free them until you're done rendering. You still need to make sure that the GL is finished before you overwrite the data, though.
3) (Harder, but worthwhile). Use VBOs. You can call glBufferData to copy data into the object, or glMapBuffer(GL_ARRAY_BUFFER, GL_WRITE_ONLY) to write directly into it. Then, you render from the VBO, not client memory. Assuming your data doesn't change too often, this will provide the best performance.

If your application crashes after implementing one of these solutions, then either you have a problem elsewhere, or there is a bug in the OpenGL-ES implementation.

This is not how OpenGL treats the client side buffer data, and I cannot find anything in the OpenGL ES specification that suggests it works otherwise (although I only checkd quickly, I may very well be wrong). On a call to glDrawArryas, the data is fully processed and the client is free to do whatever with he want the buffer afterwards whenever he chose to as soon as the function returns. If OpenGL does not draw it immediately, it is OpenGL's responsibility to copy the content to internal buffers. The user is not responsible for synchronization. So it is perfectly valid, as far as OpenGL concerns (driver bugs is another issue), to delete the buffers immediately when glDrawArrays returns.

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Quote:
Original post by Brother Bob
This is not how OpenGL treats the client side buffer data, and I cannot find anything in the OpenGL ES specification that suggests it works otherwise (although I only checkd quickly, I may very well be wrong). On a call to glDrawArryas, the data is fully processed and the client is free to do whatever with he want the buffer afterwards whenever he chose to as soon as the function returns. If OpenGL does not draw it immediately, it is OpenGL's responsibility to copy the content to internal buffers. The user is not responsible for synchronization. So it is perfectly valid, as far as OpenGL concerns (driver bugs is another issue), to delete the buffers immediately when glDrawArrays returns.


Pretty interesting. I just can say that Apple includes some samples with the SDK where they're doing exactly the same thing with static arrays. I know that doesn't necessarily have to mean much, but it looks like it was intended to work that way.


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Quote:
Original post by Brother Bob
On a call to glDrawArryas, the data is fully processed and the client is free to do whatever with he want the buffer afterwards whenever he chose to as soon as the function returns.

Yep, on closer inspection, you're right. This is a driver bug. My suggestions will suffice as workarounds, but the original code as posted is correct. I've just seen a lot of bugs caused by freeing data that's still considered valid by GL.

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