• Advertisement
  • Popular Tags

  • Popular Now

  • Advertisement
  • Similar Content

    • 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!
  • Advertisement
  • Advertisement
Sign in to follow this  

OpenGL How to quickly draw just an 2d image

This topic is 3670 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

Hi, I need just to draw an image generated(computed) my own way(raytracing). And I want to redraw it fast - every time user moves a slider(it changes parameters of illuminating model - illusion of realtime raytracing). The way I'm doing it now is to simply draw the pixels as points(in GL_POINTS mode) in ortho projection with the same z coord. But it is slow, for each pixel one glVertex3f call. How to do it faster? I tried to use glDrawPixels, but that was incredibly slow. Would glTexImage2D faster? But if it would, it accepts(according OpenGL ref) only power-of-two sized textures, and I need arbitrary sized images(user can resize the graphics window). There is SetDIBitsToDevice function(Win32), could this one be fast? Thanks for your help. I'm an OpenGL beginner, please respect it in your asnwers.

Share this post

Link to post
Share on other sites
One thing is not clear to me : is your image already stored in a bitmap, or do you output each pixel from your raytracing ? In the first case, the fastest way is to render a single quad filling your window and textured with your bitmap. POwer-of-2 textures are no more mandatory from openGL 2.0 on. if you still need them, increase your texture dimensions to the nearest power of 2 and use only the usefull part by playing with the texture coordinates.
In the second case, you could write your pixel data (color) straight to the array used by the glTexImage2D command and proceed as above.

Remember GPU's are optimized for one thing : render as many polygons as possible in the shortest time, so always prefer rendering polygons to another solution (when it's possible)

Share this post

Link to post
Share on other sites
One thing is not clear to me : is your image already stored in a bitmap, or do you output each pixel from your raytracing ?

Well, it actually doesn't matter if I process each pixel immediately or if I store them in a bitmap.

What concerns OpenGL 2, I'm not sure how it is supported in older graphics cards(for example, at this computer I'm running GeForce MX 440 ;-) ), but the trick with increasing dimensions is fine.

And vertex arrays may be also good, it does what I need exactly - get rid of many calls of glVertex3f.

Thank you guys!

Share this post

Link to post
Share on other sites
Original post by mrlocus
One thing is not clear to me : is your image already stored in a bitmap, or do you output each pixel from your raytracing ?

Well, it actually doesn't matter if I process each pixel immediately or if I store them in a bitmap.

I assume Farfadet means whether each pixel is transferred by its own to OpenGL, or else is transferred in a bulk (i.e. a bitmap with more than 1x1 pixel). Bulk transfers have a better benefit-to-cost ratio, since the (more or less same) overhead is used to transfer more pixels.

Original post by mrlocus
What concerns OpenGL 2, I'm not sure how it is supported in older graphics cards(for example, at this computer I'm running GeForce MX 440 ;-) ), but the trick with increasing dimensions is fine.

Long before OpenGL 2, there is an extension to support non-power-of-2 textures: GL_ARB_texture_rectangle or GL_EXT_texture_rectangle, resp. However, they may suffer from the fact not being power-of-2 sized in the one or other way.

Share this post

Link to post
Share on other sites
I solved it finally.

First I tried the vertex arrays, but the speed didn't change at all.

Now I draw a big Quad and set its texture. The speed increased in a big way, my old method(glVertex3f for each pixel) took about 60ms, now it takes 15ms!

As I have a very old card in my home comp(Riva TNT2! ;) ), I couldn't debug my program using an extension there, for example Riva doesn't have *_texture_rectangle extension. Hopefully, glTexSubImage2D accepts non-power-of-2 sizes. And, furthermore, it is faster than glTexImage2D.

So I first create a bigger power-of-2 texture (glTexImage2D), "render"(evaluate my equations) into part of it and set that useful part to the quad by glTexSubImage2D.

Similar topic is covered in Nehe's 35th tutorial - playing AVI video in OpenGl.

Thank you!

Share this post

Link to post
Share on other sites
just use a power of 2 sized image eg 2048x2048 + only update the top 1280x720 (or whatever) part of the texture
with glTexSubImage2d( .... );
if done this before with a raytracer, the benifits of doing this instead of drawpixels, maybe faster but more importantly u can draw to a small image eg 320x240 + then display it fullscreen with some semi-nice bilinear filtering

Share this post

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

  • Advertisement