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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 SDL_image to textured quad

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Hey I've a got 2D game going on. I used SDL and also OpenGL. For loading images I always use .TGA's and I load them myself with code I mostly took from NeHe's site. It's like this: I declare this data type:
struct TextureImage
{
   GLubyte *imageData;
   GLuint bpp;
   GLuint width;
   GLuint height;
   GLuint texID;
};

Then I declare some variable:
TextureImage *whatever;

Then I declare this function:
bool LoadTGA(TextureImage *texture, string &filename)
{
   GLubyte TGAheader[12]={0,0,2,0,0,0,0,0,0,0,0,0};
   GLubyte TGAcompare[12];
   GLubyte header[6];
   GLuint bytesPerPixel;
   GLuint imageSize;
   GLuint temp;
   GLuint type=GL_RGBA;

   FILE *file = fopen(filename.c_str(), "rb");

   if(file==NULL||
      fread(TGAcompare,1,sizeof(TGAcompare),file)!=sizeof(TGAcompare)||
      memcmp(TGAheader,TGAcompare,sizeof(TGAheader))!=0||
      fread(header,1,sizeof(header),file)!=sizeof(header))
   {
      if(file!=NULL)
         fclose(file);
      return false;
   }
   texture->width  = header[1] * 256 + header[0];
   texture->height = header[3] * 256 + header[2];

   if(texture->width<=0||texture->height<=0||(header[4]!=24 && header[4]!=32))
   {
      fclose(file);
      return false;
   }

   texture->bpp=header[4];
   bytesPerPixel=texture->bpp/8;
   imageSize=texture->width*texture->height*bytesPerPixel;

   texture->imageData = (GLubyte *)malloc(imageSize);  //Ah, malloc, C's answer to "new".  So when is this memory freed?
                                                       //you have to free it yourself NeHe has a Deinitialize function

   if(texture->imageData==NULL||fread(texture->imageData, 1, imageSize, file)!=imageSize)
   {
      if(texture->imageData!=NULL)
      {
         free(texture->imageData);  //well, I guess this is how you free it
         texture->imageData = NULL;
      }
      fclose(file);
      return false;
   }

   //for a fun time comment this out
   for(GLuint i=0; i<(unsigned int)imageSize; i+=bytesPerPixel)
   {
      temp=texture->imageData;
      texture->imageData = texture->imageData[i + 2];
      texture->imageData[i + 2] = temp;
   }

   fclose (file);

   // Build A Texture From The Data
   glGenTextures(1, &texture[0].texID);  //texture is a pointer to a TextureImage
                                         //why not just texture.texID?  why &texture[0]??  wtf
                                         //the the address of a pointer?  the first element of it?  it has no elements, wtf?
                                         //wtf could [0] possibly mean?
   //oh I remember, you use -> for pointers instead of . like above
   //so here he wants to use . so maybe ampersand on a pointer "converts" it back to a regular data type?
   //I have no idea what's going on

   glBindTexture(GL_TEXTURE_2D, texture[0].texID);  //And here it needs no ampersand.  Why?  I don't know.
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

   if(texture[0].bpp==24)
   {
      type=GL_RGB;
   }

   //Here using . instead of -> so maybe [0] takes care of it?  Then why the ampersand above?
   glTexImage2D(GL_TEXTURE_2D, 0, type, texture[0].width, texture[0].height,0, type, GL_UNSIGNED_BYTE, texture[0].imageData);

   return true;
}

So now I pass *whatever to that function along with the name of a .tga file and I can bind *whatever whenver I want and slap on some quads.
glBindTexture(GL_TEXTURE_2D, whatever.texID);
glBegin(GL_POLYGON);
   glTexCoord2f(0.0,1.0);	glVertex3f(0,768,0.0);
   glTexCoord2f(1.0,1.0);	glVertex3f(1024,768,0.0);
   glTexCoord2f(1.0,0.0);	glVertex3f(1024,0,0.0);
   glTexCoord2f(0.0,0.0);	glVertex3f(0,0,0.0);
glEnd();

But TGA's always take up a few trillion terrabytes and no one's used them since Fred Flintstone so I want to start loading .PNG's instead. I want to use SDL_image loader and using SDL_image loader for an SDL game is easy enough except I want it to load the PNG into a data type that I can bind to an OpenGL texture like I'm doing above with .tga's. I cannot find how to do this. I don't think it would take more than a page of code, I figured there would be something out there I could just block copy and figure out later but I can't find anything. I don't know why, lots of people have probably loaded .png's with SDL_image and textured OpenGL quads with them.

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Enjoy all the love of many different formats the SDL_IMage loads


bool TextureLoader::Load(std::string& filename)
{
SDL_Surface* tex = IMG_Load(filename.c_str());
if(!tex)
return false;
//setup your texture parameters however you like here
glBindTexture(...);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB8, tex->w, tex->h, 0, GL_RGB, GL_UNSIGNED_BYTE, tex->pixels);

SDL_FreeSurface(tex);
return true;
}





[Edited by - MARS_999 on July 9, 2008 1:30:19 AM]

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I don't really get it. What is this TextureLoader class? Am I supposed to write it myself and add imageWidth and all those variables to it and add the Load(string) function?

It looks to me like all it does is return true. tex is freed at the end, I don't see what the result is. I need something that I can bind and then map to a quad. Sorry I'm probably just not understanding it, I don't understand graphics very well.

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Quote:
Original post by icecubeflower
I don't really get it. What is this TextureLoader class? Am I supposed to write it myself and add imageWidth and all those variables to it and add the Load(string) function?

It looks to me like all it does is return true. tex is freed at the end, I don't see what the result is. I need something that I can bind and then map to a quad. Sorry I'm probably just not understanding it, I don't understand graphics very well.


When you call glTexImage2d, it will actually copy the data over to the video card, not just bind it. Once you done this it isn't necessary to keep the image loaded. In his snippet, he only shows how to use SDL's image library capabilities. You can use your knowledge on OpenGL's texture ability with his code to -texture a quad-. He also didn't show exactly how the params are passes as it isn't necessary, you can come up with it.

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Why do I need to make a TextureLoader class? Why do I need a class? Why can't I just make a function like this:


void Load(SDL_Surface* tex, std::string& filename)
{
tex = IMG_Load(filename.c_str());
if(!tex)
return false;
//setup your texture parameters however you like here

return true;
}



And then after I use that function I have my tex variable to work with so I can go like this back in my main program:


glBindTexture(...);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB8, tex->w, tex->h, 0, GL_RGB, GL_UNSIGNED_BYTE, tex->pixels);
SDL_FreeSurface(tex);



Really I'm not even sure why I even need that glTexImage2D function. Usually I just bind a texture and then draw a quad and I'm done. Unless I need glTexImage2D back in my Load function?

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The function you are questioning is what dumps the image into video memory! This way the video card can use its own memory rather than the slow transfer of ram -> video ram.

Here is a snippet of my texture class:

#include "Texture.h"
#include <string>
#include <sdl/sdl_image.h>
#include <sdl/sdl_opengl.h>

Texture::Texture(const char *filename)
{
// Load Texture into Memory
SDL_Surface *image = IMG_Load(filename);
if(!image)
throw std::pair<const char*, const char*>("Texture::Texture", "Error Loading Image from Disk");

// Create Video-Card Texture
glGenTextures(1, &tex_id);
glBindTexture(GL_TEXTURE_2D, tex_id);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, image->w, image->h, 0, GL_RGBA, GL_UNSIGNED_BYTE, image->pixels);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

SDL_FreeSurface(image);
}


void Texture::Bind()
{
glBindTexture(GL_TEXTURE_2D, tex_id);
}



Using something like this makes it a little neater (at least in my opinion) when binding different textures at different instances. Also the destructor can take care of any texture releasing, etc, if needed to be done in real time. =)

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I think I almost get it. That *image you declared is used and then freed on the spot. Before it's freed the image is loaded into video memory via that function I dared to question. So that function call goes out of scope. Now anytime I draw a quad that texture is going to be mapped to it until I call Texture::Texture(const char *filename) again. Am I right?

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For small projects, keep all of the texture objects in video memory. Bind which ever texture you need to use by calling the Bind method in the class, that way the next textured raster being rendered it will use the newly bound texture without having to do any IO (still in video memory). Basically the less IO you do, the faster... Much faster. :)

One way I have been doing this is creating a texture manager, where it will load images from a directory, than the user can request a reference of the texture object for rendering. Once the manager goes out of scope all the resources are freed.

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Sorry man, I don't really understand what you just said.

I don't really understand how the textures you have loaded into video memory are ever accessed again. When I did it with the LoadTGA(TextureImage *texture, string &filename) function that I listed in my first post *texture was NOT freed at the end like your *image is. It's up to me to make sure it's freed later.

That way whenever I load a new map and new monsters I assign a TextureImage* to every new TGA file by sending it into my LoadTGA() function along with the name of the file. Then my Draw() function executes continuously but as it draws the map and hero and monsters it just binds those TextureImage*'s over and over.

Your *image is freed at the end of the function. It is bound so it can be texture mapped right then. But then if something else is bound then it seems to me that the image is lost.

I just don't see how you can free the image from memory right after you bind it. The Draw() function uses that image every cycle. Why would you free it?

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