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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 GL_MAX_TEXTURE_SIZE barrier on OpenGL ES 2

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Good 'morrow, this is for Android game (possibly iOS later) : I'm currently hitting up against maximum texture size limits on some devices. I've decided to not bother with trying to support 1024x1024, but I'm aiming to support 2048x2048 as a lot of devices still have this limit (including my 2013 nexus 7).
 
Now for some games this isn't an issue, you just downsize the textures .. however I'm using a pixel perfect spritesheet for depth ordered billboards, and want to be able to draw everything with one drawcall, and I'm thinking I'm going to need at least 4096 x 2048. I can't just render with 2 drawcalls, as the sprites are interleaved randomly and have to be drawn in depth order.
[attachment=35662:zorder.jpg]
So some options I have:
  1. Half size the spritesheet on load and upsize at rendering (ugly blocky)
  2. Half size the spritesheet and half the game resolution (very involved to support 2 version of the game, but would better support different screen sizes?)
  3. Use some shader jiggery pokery to get around the limit

I'm currently thinking along the lines of 3, something like :

  • Binding 2 halves of the spritesheet to active texture 0 and 1 (each 2048 x 2048)
  • Pass the uv coords in pixel space
  • In the fragment shader, if the u coord >= 2048, then -2048 and sample from texture 1 (and vice versa).
I could also maybe make the spritesheet generator avoid placing on the boundary, and decide which spritesheet in the vertex shader, if this would help.
 
Is this feasible? What kind of penalty should I be expecting for such an approach (with a conditional in the frag shader) versus the hardware supporting it natively?

 

 

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Option 3 with a 3D texture could work, seeing as you're also limited to 8 textures at once, then just select the layer based on your UV like you say.

Hm it's kinda funny considering back 5 years to when I was keeping fragment shaders uber simple, that's compared with today's crazy goings on with MSAA, lights galore, etc! But just like today I would say aim to optimize speed rather than size, perhaps even pass the texture layer as an attribute with each vertex.

 

edit: I was reading your post more than thinking; in terms of speed it'll just be your vertex shader passing a lowp int to the fragment shader. (or if adjusting the U element then an extra vertex instruction or two) [frag shader will be the same except for referencing a varying rather than a uniform]

Edited by jezham

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Yeah I guess I'll try passing the texture ID from the vertex shader and compare with just using the fragment shader. If there's not a lot of difference I might just go for the easier method so I don't have to adjust the spritesheet code.

If there is a performance hit I can have 2 sets of shaders, depending on whether the hardware supports > 2048, so the later hardware does not pay a price for the compatibility. :)

I've also had problems with devices not supporting frame buffers > 2048 for scrolling textures, but that's a whole other problem lol. Does make you wonder how the GPU guys decide what the limits should be... It must be intriguing what goes into GPU design, although I'm sure all top secret lol.

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Is this feasible? What kind of penalty should I be expecting for such an approach (with a conditional in the frag shader) versus the hardware supporting it natively?

Depends. If you do:

float4 val0 = texture( tex0, uv );
float4 val1 = texture( tex1, uv );

finalVal = uv.y > 0.5 ? val1 : val0;

There is no branch, and the cost is only slightly less performance, and higher power consumption (since you're consuming twice the bandwidth).

But if you do:

vec2 uvDdx = ddx( uv );
vec2 uvDdy = ddy( uv );

if( uv.y )
    val = texture( tex0, uv, uvDdx, uvDdy );
else
    val = texture( tex1, uv, uvDdx, uvDdy );

Then the performance impact could be quite serious (the cards you're targeting are very bad at hiding latency) but the power consumption should stay in check.

It boils down to whether the performance decrease you get puts you below the minimum you are targeting and decide to consume more power instead.

 

I've also had problems with devices not supporting frame buffers > 2048 for scrolling textures, but that's a whole other problem lol. Does make you wonder how the GPU guys decide what the limits should be... It must be intriguing what goes into GPU design, although I'm sure all top secret lol.

Smaller resolutions means less bits in the texture unit to perform addressing and filtering. Less bits means less transistors; which translates to lower costs, less power consumption therefore less heat and increased battery life.

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I'm not sure how feasible this is for your use case, but you could have a full mipmap chain for the texture, pack sprites into different miplevels, then do an explicit miplevel lookup (desktop GL has textureLod for this, I don't know GL ES but expect that it should have similar).

It won't give you the full extra texture space that a 4096x2048 texture would, but it will give you some extra.

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If you (miss-)use mipmaps you do not get very much out of it for making it more complicated. 33,3_% to be exact. And you can hardly make full use of the smaller mipmap levels.

My question would be if you really need more then a 2048x2048 texture for what you draw as ordered billboards? The only thing you normaly draw ordered without depth write are alpha transparent objects. And everything else (including stencil transparency) can be drawn before that with depth write enabled. So you can sort for texture affiliation and only need to bind each texture once per frame.

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Some good info there from Matias regarding the decision between branchless (more texture lookups) and branched shaders (have the same issue in some other shaders, I'll have to do some tests to compare performance .. it maybe the shader compiler decides it is quicker to do both the lookups even in the branched shader).

Using mipmaps is an interesting idea and something I hadn't thought of, but as osbios says this only gains a little extra texture space at quite a bit more complexity, so I'll probably go with the simpler approach.

My question would be if you really need more then a 2048x2048 texture for what you draw as ordered billboards? The only thing you normaly draw ordered without depth write are alpha transparent objects.

This is for that situation of alpha transparent depth sorted sprites (trees etc in the screenshot). :) 

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 I don't think it can be done much faster and smaller than just adjusting your UV coords in the vertex shader.

// vertex
uniform		lowp		int	u_baseTextureID;

attribute	mediump		vec2	a_uv; // normalized UV, .x also contains texture ID

varying		lowp		int	v_textureID;
varying		mediump		vec2	v_uv;

	...
	v_textureID = a_uv.x < 1.0 ? u_baseTextureID : 1 + u_baseTextureID;
	v_uv.x = a_uv.x < 1.0 ? a_uv.x : a_uv.x - 1.0;
	v_uv.y = a_uv.y;

edit...Better still, plus allows more textures than GLES2 can shake a stick at:


    //ex. vec2(2.0, 0.0) is adjusted to vec2(0.0, 0.0) w/ texture id 2
    v_textureID = int(a_uv.x);
    v_uv = vec2(a_uv.x - float(v_textureID), a_uv.y);

I suggest your UVs are pointing at pixel centers vec2i(2047, 0) would be vec2(2047.5, 0.5) / textureDim

 

edit2: might as well go all the way; use GL_REPEAT then you only have to pass the textureID and leave the UVs as is (v_uv = a_uv). Note the advantage of doing this in the vertex shader rather than for every texel.

Edited by jezham

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