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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:

      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!
    • 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 Custom math data structure accessing same memory block

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Hi everyone,


I have been having problems with my GLXMATRIX data, when I was sending it to GLSL shader.
So I decided to do test with a simple triangle and to see if there is a problem with my math or data structure.
I created several variables:
  • GLXMATRIX projection
  • GLXMATRIX translate

Then I initialized them as Identity matrices and I uploaded perspective data to projection matrix and scaling data to translation matrix:

  • GLXMatrixPerspectiveCM(&projection, 45.0f, 800.0f/600.0f, 0.1f, 100.0f);
  • GLXMatrixScaling(&translate, 0.5f, 0.5f, 0.5f);

Perspective collumn major function looks like this.

GLXMATRIX* GLXMatrixPerspectiveCM(GLXMATRIX *pOut,float fov,float aspect, float zn,float zf) {
#ifdef TYW_DEBUG
	if (!pOut)return nullptr;
	float q = 1.0f / tan(0.5f*fov * (PI / 180.0f));
	float A = q / aspect;
	float B = (zn + zf) / (zn - zf);
	float C = (2.0f * zn * zf) / (zn - zf);

	pOut[0][0] = A;
	pOut[1][1] = q;
	pOut[2][2] = B;
	pOut[2][3] = C;
	pOut[3][2] = -1;
	pOut[3][3] = 0;
	return pOut;

Then I sended those matrices to shader.

 //SetUniformMatrix4fv(std::string progIndx, std::string unfIndx, int count, bool transpose, const float* value);

  • renderProgManager.SetUniformMatrix4fv("text.glsl", "objectPosition", 1, false, translate);
  • renderProgManager.SetUniformMatrix4fv("text.glsl", "orthoMatrix", 1, false, projection);

But instead of seing triangle properly I got this.

I could not get what was wrong. I thought the problem will be with math but it couldn't be becaue I used the same math code from OpenGL superbible. So I decided to test if my perspective matrix is wrong or is something else fucks up.This time I didn't send projection matrix and sended only translation matrix. I thought that the triangle will display at least normaly. But guess what, it wasn't. It was displaying the same, even if my translation matrix was equals to identity. The I figured out that somewhy it access same memory block when I'm modifying it.
So I decided to create GLXMATRIX pointer to see if I was right.
  • GLXMATRIX* projection
  • GLXMATRIX* translate

I created memory space for them.

  • projection = new GLXMATRIX;
  • translate = new GLXMATRIX;
Then I did all the same things that I did before. Just needed to put in some places " * " operator that I could send data to shader. Luckily, this time the triangle looked as it was supposed to look.
The thing is that I can't understand why it was like this and maybe any of you have an answer?
The data structure is basicly the same as it is defined in D3DX math library.
typedef struct _GLMATRIX {
	union {
		struct {
			float _11, _21, _31, _41;
			float _12, _22, _32, _42;
			float _13, _23, _33, _43;
			float _14, _24, _34, _44;
		float m[4][4];

typedef struct GLXMATRIX : public GLMATRIX {
	GLXMATRIX(const float*);
		float m11, float m21, float m31, float m41,
		float m12, float m22, float m32, float m42,
		float m13, float m23, float m33, float m43,
		float m14, float m24, float m34, float m44);

	//acces grants
	float& operator () (unsigned int row, unsigned int col);
	float  operator () (unsigned int row, unsigned int col) const;

	//casting operators
	operator float* ();
	operator const float* () const;

	//assignement operators
	GLXMATRIX& operator *= (const  GLXMATRIX&);
	GLXMATRIX& operator += (const  GLXMATRIX&);
	GLXMATRIX& operator -= (const  GLXMATRIX&);
	GLXMATRIX& operator *= (float);
	GLXMATRIX& operator /= (float);

	//unary operators
	GLXMATRIX operator + () const;
	GLXMATRIX operator - () const;

	//binary operators
	GLXMATRIX operator * (const GLXMATRIX&) const;
	GLXMATRIX operator + (const GLXMATRIX&) const;
	GLXMATRIX operator - (const GLXMATRIX&) const;
	GLXMATRIX operator * (float) const;
	GLXMATRIX operator / (float) const;

	friend GLXMATRIX operator * (float, const GLXMATRIX&);

	bool operator == (const GLXMATRIX&) const;
	bool operator != (const GLXMATRIX&) const;

//casting operators
inline GLXMATRIX::operator float* ()
	return (float*)&_11;

inline GLXMATRIX::operator const float* () const
	return (const float*)&_11;



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When I wrote this article I noticed that the way I access array in Perspective function was totally wrong and this explains why it was like this. Strangely I was not getting any errors.

So the fixed math function looks like this

GLXMATRIX* GLXMatrixPerspectiveCM(GLXMATRIX *pOut,	float fov, float aspect, float zn,	float zf) {
#ifdef TYW_DEBUG
	if (!pOut)return nullptr;
	float q = 1.0f / tan(0.5f*fov * (PI / 180.0f));
	float A = q / aspect;
	float B = (zn + zf) / (zn - zf);
	float C = (2.0f * zn * zf) / (zn - zf);

	pOut->m[0][0] = A;
	pOut->m[1][1] = q;
	pOut->m[2][2] = B;
	pOut->m[2][3] = C;
	pOut->m[3][2] = -1;
	pOut->m[3][3] = 1;
	return pOut;

However in OpenGL supperbible at the array location [3][3] the data is setted to zero but in here I setted to one because the triangle was not showing to me. Do you know why it is like this?

Edited by renderkid

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I managed to solve the problem with perspective matrix. Jus needed to position triangle on z = -1 axis. However I found out that I have to use row major and not collumn major even though my multiplication in shader looks like this

  • gl_Position = perspective * translate * rotation * object;

As the main problem of this thread was solved I moved to new thread which has the problem with rotation-> http://www.gamedev.net/topic/673538-rotation-matrix-stretches-geometry/

Edited by renderkid

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