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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:

      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.


    • 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 ==========  
      #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; }  
    • 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!
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OpenGL Bloom Fail

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I have just implemented bloom in my engine but on the OpenGL side I have these black artifacts.

In Direct3D 9 they are fine.

They are both using the exact same shaders, being fed the exact same data, and using the same HDR formats (16-bit float).

I know that the problem is in the blur filters, both horizontal and vertical, but I can’t see why it is happening, especially when it doesn’t happen in Direct3D 9.

Horizontal blur.

#version 130
precision mediump float;
invariant gl_Position;
float shadow2dDepth(sampler2D s,vec2 v){return texture(s,v).z;}
out vec2 LSG_VERT_OUT_PIXEL_IN_379_0/*_vOut2dTex0*/;
in vec2 _vIn2dTex0;
in vec3 _vInPos;
uniform mat4x4 g_mModelViewProjMatrix;

void main(){
gl_Position = ((g_mModelViewProjMatrix) * (vec4( _vInPos, 1.0 )));

LSG_VERT_OUT_PIXEL_IN_379_0/*_vOut2dTex0*/ = _vIn2dTex0;

#version 130
precision mediump float;
out vec4 lsg_vColor[8];
float shadow2dDepth(sampler2D s,vec2 v){return texture(s,v).z;}
out vec4 _vOutColor;
in vec2 LSG_VERT_OUT_PIXEL_IN_379_0/*_vIn2dTex0*/;
in vec4 LSG_VERT_OUT_PIXEL_IN_375_0/*_vInPos*/;

uniform sampler2D g_sSampler2dTex0;

uniform float g_fOffsets[9];
uniform float g_fWeights[9];

void main() {
_vOutColor = vec4( 0.0, 0.0, 0.0, 0.0 );

for ( int I = 0; I < 9; I++ ) {
_vOutColor += (texture( g_sSampler2dTex0, LSG_VERT_OUT_PIXEL_IN_379_0/*_vIn2dTex0*/ +
vec2( g_fOffsets, 0.0 ) ) * g_fWeights);


_vOutColor.w = 1.0;

I know it looks a little strange. This was generated output from my own shader language, and I added back some of the whitespace to make it more readable.

g_fOffsets has normal-looking values from -0.0049999999 to 0.0049999999.


[0x0] 0.032394581
[0x1] 0.077710561
[0x2] 0.14518245
[0x3] 0.21123920
[0x4] 0.23936538
[0x5] 0.21123920
[0x6] 0.14518245
[0x7] 0.077710561
[0x8] 0.032394581

The only difference with the vertical pass is g_fOffsets, which is normal because it is based off the height instead of the image.
Any ideas?

L. Spiro

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Those black artifacts are often indicative of NaN Pixels which get drawn as black on most GPUs.

NaN mostly results from divisions by 0. One typical example being 0/0.

Since any operation with a NaN value results in a NaN, you then get those black block artifacts when applying a filter.

You can test this in GLSL at the end of you shader with this code snippet:

if (any(isnan(color))) {
color = vec4(1,0,0,1);

This will set NaN pixels to red.

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That was helpful information.

I found out that my bright pass is writing NaN values to the texture due to a dot() with a zero-vector (black texels).
Why it doesn’t have to all black texels I have no clue, but I applied the appropriate checks and fixed it.

Thank you.

L. Spiro

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I found out that my bright pass is writing NaN values to the texture due to a dot() with a zero-vector (black texels).

Dot has no division, only multiplications... so it should not be the cause of NaN-value. The issue must be somewhere before that.. like it already was a NaN-value vector. Possible cause exponent of the floating point is not correctly interpreted (all bits are set to 1, according to IEEE-754).

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In glsl, the pow(x, y) function return value is undefined if x < 0 or if x = 0 && y = 0. I once had a situation where the specular multiplier and specular exponent of a specular map were both zero at some texels, which caused pow to return NaN. You can also check for that.

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I guess I was thinking dot() was a target because the returned value is relative to the lengths of the input vectors, and as we all know, a 0-vector has to be handled as a special case in order to avoid division by 0.

However it is correct in reality that both dot() and cross() have no divides.

Except apparently in OpenGL and OpenGL ES 2 implementations.
It was the cause for the large black blocks. Simply by changing from this (bright pass, the only pass before doing a horizontal blur):

float fLuminance = dot( vAverage.rgb, vWeight );
if( fLuminance < g_fThresh ) {
vAverage = vec4( 0.0f, 0.0f, 0.0f, 1.0f );

to this:

float fLuminance = dot( vAverage.rgb, vWeight );
if( fLuminance < g_fThresh || isnan( fLuminance ) ) {
vAverage = vec4( 0.0f, 0.0f, 0.0f, 1.0f );

made the blocks go away. I rendered the result of the horizontal blue before and after this change and confirmed that without this change, the first blur has black streaks, with the change it is perfect.

Meanwhile, since a typical dot() and cross() do not have divides, Direct3D 9 was working fine.
This appears to be unnecessary extra work being done by OpenGL. There is no reason for it to generate NaN here, unless it is specifically testing for the case of a 0-length input vector.

I do still have black dots (rather than blocks) and those appear in Direct3D 9 also, but I haven’t yet been able to find the cause.
Since I can render the bright pass and blurs, and they are always perfect, I know that it is in the last stage which combines them and does the tone mapping.

Anyway I will find it eventually.

L. Spiro

I was thinking about another idea I have been entertaining—that the source image has NaN values in it that I could never see before because they are black pixels and the end result is still black.
Just tested it and it is correct.
It isn’t in the pow() but it is in the main image result.
I will remove my dot() checks since they are now superfluous, and will find the actual cause of my woes soon.

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However it is correct in reality that both dot() and cross() have no divides.

Except apparently in OpenGL and OpenGL ES 2 implementations.
It was the cause for the large black blocks. Simply by changing from this (bright pass, the only pass before doing a horizontal blur):

I don't think that makes sense. As far as I know, the only way for dot to return NaN is if one of the components are NaN. Are you sure the input is good..?

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Have you checked if the inputs to [font=courier new,courier,monospace]dot[/font] are [font=courier new,courier,monospace]nan[/font]s? e.g.if( any(isnan( vAverage.rgb )) || any(isnan( vWeight )) ) {
vAverage = vec4( 0.0f, 1.0f, 0.0f, 1.0f );
float fLuminance = dot( vAverage.rgb, vWeight );

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For both replies, read my edit.

The dot() was not the culprit, the source image was. Something I had not considered accepting before because the results were always exactly what I had expected (a [0,0,0] input generates a [0,0,0] output regardless of any Nan’s).
I changed my checks for isnan() to those output by my main shader (which generates the image to be pre-processed), which I have used since the beginning, and that alone eliminated all errors in OpenGL.
Actually, now only Direct3D 9 has remaining problems.

However my check for isnan() comes at the very end of that shader, and is present in ALL variants. If a NaN is present, it cannot possibly be due to an NaN value being stored in the main image. So now OpenGL and OpenG ES 2 are working while Direct3D 9 is in the wrong. With my above change, only Direct3D 9 has black artifacts, and OpenGL is entirely 100% perfect, including the overall luminance calculation which was also sometimes turning full black due to NaN.

From here out I need to focus on the Direct3D side of things, but I gained enough insight from this topic that I should be able to solve the remaining issues on my own.

L. Spiro

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