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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 Obtaining part of an image and bind that as texture

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I have lots of texture's and I thought it'd be a good idea to store them by category in one bigger texture. That is, images are placed in the bigger image with known x, y, w, h values, then I load the big image into memory and pick one of the smaller images inside. That smaller image should be loaded into OpenGL. I use Corona for the image loading/converting, which returns me a void* to the pixel buffer. Code:
#include <corona.h>

class Textures
{
    public:
        void load(int, char *[]);

        GLuint *ids;

    private:
        Texture *textures;
        int size;
};

void Textures::load(int isize, char *filenames[])
{
    if (isize > 0)
    {
        if (size)
        {
            free();
        }

        size = isize;
        textures = new (nothrow) Texture[size];
        if (!textures)
        {
            fatal << "could not allocate memory" << POS;
            quit();
        }

        ids = new (nothrow) GLuint[size];
        if (!ids)
        {
            fatal << "could not allocate memory" << POS;
            quit();
        }

        corona::Image *image = NULL;
        for (int i = 0; i < size; i++)
        {
            image = corona::OpenImage(filenames, corona::PF_R8G8B8A8);
            if (image)
            {
                glGenTextures(1, &textures.texture);
                textures.w = image->getWidth();
                textures.h = image->getHeight();

                ids = textures.texture;
                glBindTexture(GL_TEXTURE_2D, textures.texture);

                glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
                glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
                glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
                glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

                glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, image->getWidth(), image->getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, image->getPixels());
            }
            else
            { warning << "could not allocate memory or load image [" << filenames << "]" << POS; }
        }
        delete image;
    }
    else
    { warning << "textures already loaded [" << isize << "]" << POS; }
}
Can I somehow cut a part of the pixel buffer and put that into OpenGL? Or do we have a function in OpenGL for this? Thank you, Decrius

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You can send only a subset (a rectangular region) of the data in memory, to OpenGL with glTexSubImage2D (http://www.opengl.org/sdk/docs/man/xhtml/glTexSubImage2D.xml). Just make sure you set the glPixelStore parameters correctly (GL_UNPACK_SKIP_ROWS, GL_UNPACK_SKIP_PIXELS, GL_UNPACK_ROW_LENGTH).

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Doesn't really seems what I'm looking for...

I wrote this function, though it doesn't really works...

#include <corona.h>

class Textures
{
public:
void load(int, char *[]);
void getPixels(unsigned char *, int, int, int, int, int, int);

GLuint *ids;

private:
Texture *textures;
int size;
};

void Textures::load(int isize, char *filenames[])
{
if (isize > 0)
{
if (size)
{
free();
}

size = isize;
textures = new (nothrow) Texture[size];
if (!textures)
{
fatal << "could not allocate memory" << POS;
quit();
}

ids = new (nothrow) GLuint[size];
if (!ids)
{
fatal << "could not allocate memory" << POS;
quit();
}

corona::Image *image = NULL;
for (int i = 0; i < size; i++)
{
image = corona::OpenImage(filenames, corona::PF_R8G8B8A8);
if (image)
{
glGenTextures(1, &textures.texture);
textures.w = image->getWidth();
textures.h = image->getHeight();

ids = textures.texture;
glBindTexture(GL_TEXTURE_2D, textures.texture);

glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

if (image->getWidth() == 1000)
{
getPixels((unsigned char *) image->getPixels(), 200, 20, image->getWidth() - 200, image->getHeight() - 20, image->getWidth(), image->getHeight());
}

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, image->getWidth(), image->getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, (void *) image->getPixels());
}
else
{ warning << "could not allocate memory or load image [" << filenames << "]" << POS; }
}
delete image;
}
else
{ warning << "textures already loaded [" << isize << "]" << POS; }
}

void Textures::getPixels(unsigned char *pixels, int x, int y, int w, int h, int w_max, int h_max)
{
if (!((x <= 0 || (x + w) >= w_max) && (y <= 0 || (y + h) >= h_max) && w >= w_max && h >= h_max))
{
unsigned char *new_pixels = new unsigned char [w * h * 4];
for (int ih = 0; ih < h; ih++)
{
for (int iw = 0; iw < w; iw++)
{
new_pixels[iw * ih * 4] = pixels[(x + iw) * (y + ih) * 4];
}
}
*pixels = *new_pixels;
delete [] new_pixels;
}
}

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If I understand you correctly, you want to take many smaller images put them into a large texture atlas, and then grab some image out of that atlas to render with?

Well if you know how large of texture sizes your card can deal with, you create as large as you want up to the limit size, and then call glTexSubImage2D() and upload that smaller texture into the larger one and then later use the texture coordinates to reference that image. Not sure if that is what you are looking for....

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Quote:
Original post by MARS_999
If I understand you correctly, you want to take many smaller images put them into a large texture atlas, and then grab some image out of that atlas to render with?

Well if you know how large of texture sizes your card can deal with, you create as large as you want up to the limit size, and then call glTexSubImage2D() and upload that smaller texture into the larger one and then later use the texture coordinates to reference that image. Not sure if that is what you are looking for....


Yes, I could've done that too, but I thought selecting a part of the texture before uploading would be much faster.

Quote:
Original post by V-man
Why don't you just use a paint software and make separate files?


It's already seperated, but I want them to be sticking together in categories...for example:

All normal buttons, selected buttons, pressed buttons and disabled buttons in one image, because I can have around 30 buttons.

So, OR uploading one file and handling it, OR uploading 120 small images directly into memory.

First method requires only one request from the harddisk, and is thus faster I think.

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If anyone is interested in the code:

unsigned char *getPixels(unsigned char *, unsigned char *, int, int, int, int, int, int);

int main()
{
// load texture into memory, in this case it is in 'image->getPixels()' from Corona
int width = 200;
int height = 800;

unsigned char *pixels = new unsigned char [width * height * 4];
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, (void *)
getPixels((unsigned char *) image->getPixels(), pixels, 0, 0, width, height, image->getWidth(), image->getHeight()));
delete [] pixels;
}

unsigned char *getPixels(unsigned char *pixels, unsigned char *new_pixels, int x, int y, int w, int h, int w_max, int h_max)
{
if (x >= 0 && y >= 0 && w > 0 && h > 0 && ((w - x) < w_max || (h - y) < h_max))
{
for (int ih = 0; ih < h; ih++)
{
for (int iw = 0; iw < w; iw++)
{
int npos = (iw * 4) + (ih * w * 4);
int opos = ((x + iw + ((w_max - w) * ih)) * 4) + ((y + ih) * w * 4);

new_pixels[npos] = pixels[opos];
new_pixels[npos + 1] = pixels[opos + 1];
new_pixels[npos + 2] = pixels[opos + 2];
new_pixels[npos + 3] = pixels[opos + 3];
}
}
return new_pixels;
}
return pixels;
}

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Why should ndhb's solution not work for you? From your code snippets it seems me that the pixel format of your files is useable for OpenGL. Then, glPixelStore can be used to specify the rectangular texture region out of a bigger source image. Furthur, using glTexSubImage can be more efficient than using glTexImage. IMHO his suggestion is definitely worth a look, since it unburdens you from making copies of image portions.

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