• Advertisement
  • Popular Tags

  • Popular Now

  • Advertisement
  • Similar Content

    • 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!
    • By Jens Eckervogt
      Hello guys, 
       
      Please tell me! 
      How do I know? Why does wavefront not show for me?
      I already checked I have non errors yet.
      using OpenTK; using System.Collections.Generic; using System.IO; using System.Text; namespace Tutorial_08.net.sourceskyboxer { public class WaveFrontLoader { private static List<Vector3> inPositions; private static List<Vector2> inTexcoords; private static List<Vector3> inNormals; private static List<float> positions; private static List<float> texcoords; private static List<int> indices; public static RawModel LoadObjModel(string filename, Loader loader) { inPositions = new List<Vector3>(); inTexcoords = new List<Vector2>(); inNormals = new List<Vector3>(); positions = new List<float>(); texcoords = new List<float>(); indices = new List<int>(); int nextIdx = 0; using (var reader = new StreamReader(File.Open("Contents/" + filename + ".obj", FileMode.Open), Encoding.UTF8)) { string line = reader.ReadLine(); int i = reader.Read(); while (true) { string[] currentLine = line.Split(); if (currentLine[0] == "v") { Vector3 pos = new Vector3(float.Parse(currentLine[1]), float.Parse(currentLine[2]), float.Parse(currentLine[3])); inPositions.Add(pos); if (currentLine[1] == "t") { Vector2 tex = new Vector2(float.Parse(currentLine[1]), float.Parse(currentLine[2])); inTexcoords.Add(tex); } if (currentLine[1] == "n") { Vector3 nom = new Vector3(float.Parse(currentLine[1]), float.Parse(currentLine[2]), float.Parse(currentLine[3])); inNormals.Add(nom); } } if (currentLine[0] == "f") { Vector3 pos = inPositions[0]; positions.Add(pos.X); positions.Add(pos.Y); positions.Add(pos.Z); Vector2 tc = inTexcoords[0]; texcoords.Add(tc.X); texcoords.Add(tc.Y); indices.Add(nextIdx); ++nextIdx; } reader.Close(); return loader.loadToVAO(positions.ToArray(), texcoords.ToArray(), indices.ToArray()); } } } } } And It have tried other method but it can't show for me.  I am mad now. Because any OpenTK developers won't help me.
      Please help me how do I fix.

      And my download (mega.nz) should it is original but I tried no success...
      - Add blend source and png file here I have tried tried,.....  
       
      PS: Why is our community not active? I wait very longer. Stop to lie me!
      Thanks !
  • Advertisement
  • Advertisement
Sign in to follow this  

OpenGL Comparing two textures in openGL

This topic is 818 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

I'm new to OpenGL, in my android game I'm looking for a way to compare two textures to tell me the similarity of two in percent value or in any other way! I know how to to this with two bitmap images but I really need to use a method to compare two textures.

Question is: Is there any way to compare two textures as we compare two images? Like comparing two images pixel by pixel? 

any resources? 

Share this post


Link to post
Share on other sites
Advertisement

Do you need the result on the CPU or is it OK if it stays on the GPU?  If the former, it can be done, but you're not going to get acceptable performance from it, so you may need to totally redesign your algorithm.  It might help us to help you a bit more if you talked a little about why you're doing this, what you want to do with the result, and so on.

Share this post


Link to post
Share on other sites

which version of ogles are you using if 1.0 forget about performance,

for 2.0 and above theres something in glsl like texture2d(for sampler2d)

 

values are between 0..1 for all channels.

 

either way you always load textures from a file so you could do that on cpu when loading textures to opengl.

 

but like mhagain said you must tell us more like which ver of ogles, and what are you trying to do.

Share this post


Link to post
Share on other sites

Do you need the result on the CPU or is it OK if it stays on the GPU?  If the former, it can be done, but you're not going to get acceptable performance from it, so you may need to totally redesign your algorithm.  It might help us to help you a bit more if you talked a little about why you're doing this, what you want to do with the result, and so on.

 

 

which version of ogles are you using if 1.0 forget about performance,

for 2.0 and above theres something in glsl like texture2d(for sampler2d)

 

values are between 0..1 for all channels.

 

either way you always load textures from a file so you could do that on cpu when loading textures to opengl.

 

but like mhagain said you must tell us more like which ver of ogles, and what are you trying to do.

 

 

i am making an origami like game and user folds the paper in 2D Space, i want to check if the final texture is what i wanted the user to make or not, i am using opengl 1! 

does i need to upgrade to 2.0?! and if so, how to achieve this by that?

Share this post


Link to post
Share on other sites

well doing that in es 1.0 is only acceptable if you do the check only once, if you manage to do it after every change of the origami then you are 'screwed'

it really depends on the size of the texture itself (screen size aswell) let me be clear first of all you load image to unisgned char * array then you upload that to texture, 

then depending on the screenspace of origami, (the window where you draw it - this is your compare space you will need to make another unsigned char * base_origami = new unsigned char[that_screen_width * that_screen_height * 4] (i recall that es 1.0 uses 32 bit colorspace [rgba])

then you draw that texture you want to compare (as the base) to that screen and call glReadPixels() where you upload screen to base_origami

then to actually compare textures you will have to draw the actual folded origami, and then again call glReadPixels but to another unsigned char array

HOWEVER this won't guarantee you 100% image recognition, there could be a thing with texture borders so colors wont match additionally you will have to add specific drawing routine to draw only the folded origami without any additional draw calls. (like colored lines etc), also backgrounds of both base origami and folded origami must be the same.

then you go in a loop on cpu side and compare these two arrays.

 

so when you have like 95-100% similarity then you are done they should be the same.

This is really not the thing you would like to go for, so maybe you could post here images of a base image of origami, and the folded one  (not completed but folded somehow)

so then we could think of something else.

 

The same problem is for es 2.0, you will have to use glreadpixels aswell but you could compare each fragment in shader (knowing the floating point inaccuracy) if they do not match you flag output color alpha as lets say 0 and if they do match you flag output red color (you dont change the alpha), then anyway you have to call glreadpixels to find every 0 in alpha value, this would suck either but should be faster a bit. too bad we cant change fragment coord in fragment shader and vertex shader wont interpolate through all pixels in texture so we could write only to another texture 1 pixel and glreadpixels one pixel so we acutally could read it back even in realtime. anyway for es 3.0, you could compare everything in shader and use transformfeedback to fill an array on cpu (or something) so you could actually have rapid check.

 

so again we need more details, because your way won't work as you expect.

Edited by WiredCat

Share this post


Link to post
Share on other sites
Just to add a possible alternative view, might it be easier to remember the list of transformations needed to fold the paper to get the final result and a list of actions taken by the player and simply compare the list and take into account error.

Share this post


Link to post
Share on other sites

well doing that in es 1.0 is only acceptable if you do the check only once, if you manage to do it after every change of the origami then you are 'screwed'

it really depends on the size of the texture itself (screen size aswell) let me be clear first of all you load image to unisgned char * array then you upload that to texture, 

then depending on the screenspace of origami, (the window where you draw it - this is your compare space you will need to make another unsigned char * base_origami = new unsigned char[that_screen_width * that_screen_height * 4] (i recall that es 1.0 uses 32 bit colorspace [rgba])

then you draw that texture you want to compare (as the base) to that screen and call glReadPixels() where you upload screen to base_origami

then to actually compare textures you will have to draw the actual folded origami, and then again call glReadPixels but to another unsigned char array

HOWEVER this won't guarantee you 100% image recognition, there could be a thing with texture borders so colors wont match additionally you will have to add specific drawing routine to draw only the folded origami without any additional draw calls. (like colored lines etc), also backgrounds of both base origami and folded origami must be the same.

then you go in a loop on cpu side and compare these two arrays.

 

so when you have like 95-100% similarity then you are done they should be the same.

This is really not the thing you would like to go for, so maybe you could post here images of a base image of origami, and the folded one  (not completed but folded somehow)

so then we could think of something else.

 

The same problem is for es 2.0, you will have to use glreadpixels aswell but you could compare each fragment in shader (knowing the floating point inaccuracy) if they do not match you flag output color alpha as lets say 0 and if they do match you flag output red color (you dont change the alpha), then anyway you have to call glreadpixels to find every 0 in alpha value, this would suck either but should be faster a bit. too bad we cant change fragment coord in fragment shader and vertex shader wont interpolate through all pixels in texture so we could write only to another texture 1 pixel and glreadpixels one pixel so we acutally could read it back even in realtime. anyway for es 3.0, you could compare everything in shader and use transformfeedback to fill an array on cpu (or something) so you could actually have rapid check.

 

so again we need more details, because your way won't work as you expect.

 

here is some pictures of it (the dashed line is not drawn in opengl and is just a test image on top of opengl render space)

 

1_a2377.jpg

 

2_dc380.jpg

 

3_c29f2.jpg

Share this post


Link to post
Share on other sites

Just to add a possible alternative view, might it be easier to remember the list of transformations needed to fold the paper to get the final result and a list of actions taken by the player and simply compare the list and take into account error.

thats not possible because the user may use different ways to achieve the final shape... 

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement