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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 How To Create Pre-Multiplied Alpha for use with OpenGL

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I feel like this should be a simple answer, but for the life of me I cannot find it.

I've been rendering my game using the alpha blend mode:

glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);


but have been getting the gray outlines around a lot of my png images like Riruilo has outlined in this post on idevgames.com: http://www.idevgames...thread-966.html

What I gathered from that post is that to fix the problem I should convert all my images (currently in png format) to premultiplied alpha png's, and use the alpha blend mode:

glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);

So my question is this:

How do you convert a normal png to a premultiplied alpha png?

I had thought this would exist as a feature (like a checkbox) within Photoshop or GIMP or Paint.Net, but am unable to find it. I understand that one could convert the png's on loading into the correct format, but I would prefer to have them in the correct format before loading. Could anyone shed some light on this issue, I'm feeling very dumb being unable to find out this can be done.

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AFAIK the PNG standard explicitly requires non-premultiplied alpha. So image editors behave correctly if they do not allow you to save as premultiplied.
I had similar problem and resolved it by using separate color and mask images (thus transparent pixels had color as well), compositing them in game editor and converting to compressed texture format with included mipmaps.

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I'm afraid I don't think I understand your process. So if I have this right, you made 2 "pngs" (or whatever image format you used) for each image you have. One is the actual image itself, and the other is am image that represents all the alpha values of the first, with alpha represented as a shade between black and white? If this is what you have done (I think I'm getting something wrong), then why not just use a single png image and multiply the RGB values by the alpha value of that single image to get to "pre-multiplied alpha" state.

Just in case it matters, I should mention that I have many images with alpha values that fall between 0 and 1, and are not simply just opaque or transparent.

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Well, here's short tutorial about doing it in gimp (the wording might be incorrect, you need to know gimp).

Assumption:
You have an image with alpha value.

1. Load the image with gimp, call the layer "image"
2. Right-click the layer and select "mask from alpha"
3. Left click on alpha layer(white border around right thumbnail) => Ctrl+C => Ctrl+V
4. A new temporary layer exists, right click and choose "new layer", rename it to "alpha"
5. Create a new layer with black (0x000000) and call the layer "background"
6. Adjust the layer like this:
- alpha
- image
- background
7. right click the "image" layer and choose "merge with underlying layer"
8. right click the resulting layer and choose "create opaque alpha mask"
9. select alpha layer => Ctrl+C => select alpha channel of "image" layer => Ctrl+V => anchor
10. delete alpha layer
11. save file as png

This should leave you with the premultiplied image with alpha layer.

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I'm afraid I don't think I understand your process. So if I have this right, you made 2 "pngs" (or whatever image format you used) for each image you have. One is the actual image itself, and the other is am image that represents all the alpha values of the first, with alpha represented as a shade between black and white? If this is what you have done (I think I'm getting something wrong), then why not just use a single png image and multiply the RGB values by the alpha value of that single image to get to "pre-multiplied alpha" state.

Just in case it matters, I should mention that I have many images with alpha values that fall between 0 and 1, and are not simply just opaque or transparent.

Yes, I am using seaparate color images and grayscale masks (and thus non-premultiplied textures).
The reason is twofold:

  1. It is easier to edit images this way. Although in theory GIMP should allow me to save color values for fully transparent pixels to png, these more than often get "lost" is some editing steps.
  2. I want to have full control over how colors are mixed in mipmap creation. n certain textures (foliage). Premultiplied alpha means, that transparent pixels do not contribute any color to scaled down image, but for some textures (foliage) is is sometimes preferable to let these to "bleed" certain color into mipmap.

I am currently using edge detection filter on alpha while generating foliage mipmaps and this needs non-premultiplied colors anyways.

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Thank you both for your replies. I ended up using Ashaman73's approach using GIMP. Thanks a lot, it worked great! For anyone who is not familiar with GIMP, I will post his instructions but for GIMP 2.6:


1. Load the image with GIMP, In the layer window, name the image layer "image".
2. Right-click the layer and select "Add Layer Mask". Select "Transfer layer's alpha channel", click add.
3. Create a new layer by hitting the "Create new layer" button in the bottom left of the layer window, call this layer "Alpha"
4. Left click on the alpha mask of the "image" layer (white border around right thumbnail) => Ctrl+C.
5. Left click on the "Alpha" layer => Ctrl+V.
6. Right click on the new temporary layer that is created, select "Anchor Layer".
7. Create a new layer with black (0x000000) and call the layer "background".
8. Order the layer like this (by left clicking and dragging the layers around):
- alpha
- image
- background
9. right click the "image" layer and choose "Merge Down"
10. right click the resulting layer and select "Add Layer Mask". Select "White (full opacity)", click add.
11. select the "Alpha" layer => Ctrl+C => select alpha mask of "background" layer => Ctrl+V.
12. Right click on the new temporary layer, select "Anchor Layer".
13. delete the "Alpha" layer.
14. save file as png.

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