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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 Resources on heightmaps?

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Hi! Could somebody point me to some information dealing with heightmaps? (best image format to store them, load them, how to convert them to polygonal geometry and viceversa, etc). Specific OpenGL oriented implementation details would also appreciated!

 

While I'm looking for details on how to implement them myself, most articles I found deal with already existing tools so they're not useful to me : /

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This has been discussed several times. I'll do a quick recap of heightmaps and terrain algorithms.

Terrain algorithms: dead. Just brute force. Caveat: perhaps using pixel-based tracing might make sense.

 

Heightmaps: they are 2D array of values.

Format to use: everything lossless will fit. I like PNG 16-bit grayscale. A raw dump might be more appropriate in some cases. Multichannel recomposition (value = red + (green << 8) + (blue << 16)) is hard to work with but at least it won't get garbled if some processing program does not support it. Floating-point based formats are to be taken with extra super special care.

How to convert them: they are a bunch of triangles! In the past, several methods have been proposed. In the end, they're not really required unless going for AAA quality, and even in this case, you'll find out many games triangolate trivially.

OpenGL implementation: there are plenty.

 

You're better with a specific question.

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Great, I already have a PNG loader.

 

Now, as for specific question. Well, what pixels in a heightmap represent? Vertices of a triangle? Quads?

 

I was thinking that maybe I could draw one with triangle strips, considering each pixel as a vertex, and using the (X,Y) positions as indexes for indexed drawing, though I'm not so sure since I can't picture it on my head yet. Got set up the loader and a PNG file made up of random noise. I'm trying to code it right now.

 

I'm using LWJGL by the way.

Edited by TheChubu

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Generally the pixels are consodered to be the vertices, and you draw triangles betwwen them.

There are different ways to draw the triangles though.

4 triangles with an imaginary middle vertex that is the average of the 4 pixel vertices in the corners

2 triangles

2 triangles with alternating direction for diagonal (to make the tiling not so obvious?)

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Thanks! Thats useful information.

 

Anyway, I did ended up rendering something out of a grayscale image, though I just set up GL_TRIANGLE_STRIP and that's it, so the vertices have no coherence at all. I have no idea what is going on the upper side of the pic (all those horizontal lines).

 

Now I'll try to correct the vertices...

 

 

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Yes! Got it! Though there is something terribly wrong with my depth test I think.


GL11.glEnable(GL11.GL_CULL_FACE);
GL11.glCullFace(GL11.GL_BACK);
GL11.glFrontFace(GL11.GL_CW);
 
GL11.glEnable(GL11.GL_DEPTH_TEST);
GL11.glDepthMask(true);
GL11.glDepthFunc(GL11.GL_GEQUAL);
GL11.glDepthRange(0.0f, 1.0f);
 

If i change it to GL_LEQUAL seems like every depth test fails and I see nothing. Probably there is something wrong with the data or my perspective matrix, maybe I'm not drawing in the correct order.

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Terrain algorithms: dead. Just brute force.

Though I kind of agree with that, "dead" is not 100% right. It still makes sense to use some kind of LOD in many situations, for two reasons.

 

1. Brute force is OK for small to medium view ranges but simply impossible otherwise, unless your resolution is extremely poor. If you have, say, a resolution of 1 meter and you brute force with a 2 kilometer visible range (which is about half of what you see in real life), that's a ... huge ... budget. Now if you think 1 meter is too coarse, you might want to add tesselation, which further increases the number of vertices.

 

2. Brute force creates a lot of small triangles in the distance. Small triangles are fragment shader poison. One does not normally want to have too many triangles that are "too small", in particular one does not want triangles that are hardly larger than a fragment (or, worse, smaller).

 

Insofar I would word it as "terrain algorithms are not THAT important any more, and may be unnecessary in some cases, while in other cases something very coarse is totally sufficient".

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Hi! Well, I got it working. I wasn't clearing the depth buffer so It added up after each frame and I wasn't seeing anything biggrin.png

 

I load the image and get the (x,y,z) coords like this: The x is the X of the pixel in the image, the y is the avg of the red green and blue colors at that pixel (pointless to avg in grayscale though) and the z is the Y coordinate of the pixel of the image. Color of the vertex is the color of the pixel.

 

Got some rotations/translations working too, so here are the views from above and below the mesh (from below it looks like some crazy cloudy thing).

 

Now I need to implement a proper camera.

 

Thanks for the help guys!

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