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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.

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      - Rendering large amounts of static meshes
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      - Wind animations based on vertex displacement
      - A very basic integration of the Bullet physics engine
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      Features I would like to have:
      - Global illumination methods
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      - Occlusion culling
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      - Scripting
      - Level Editing
      - Sound system
      - Optimization techniques

      Books I have so far:
      - Real-Time Rendering Third Edition
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      - 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
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      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:
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      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 DX11 changing window coordinate origin (upper-left -> lower-left)

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hi there,

 

I want to change the window coordinate origin to use OpenGL conventions (ie. lower-left is (0,0)). 
In GLSL the default is lower-left, however you can change to upper-left using layout(origin_upper_left). Is there such a thing in HLSL that changes to lower-left?

 

best regards,

Yours3!f

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Which part of the vertex-transform / rasterization pipeline do you want to change?

Both OpenGL and D3D use x,y=-1,-1 for the lower left, and x,y=1,1 for the top right.

You can construct your projection matrices differently (concatenate with a "scale y by -1" matrix) if you want to flip that upside down.

After projection into NDC (-1 to 1 range). The viewport is used to convert into pixel coordinates. D3D's viewport coords do treat the upper left as the 0,0 origin. You can flip these with something like:
vp.y = renderTarget.height - vp.y - vp.height;

With texture coords, GL uses lower left origin and D3D uses upper left. Easy to flip with uv.y=1-uv.y;

D3D typically doesn't have options to adopt GL's conventions at the API level, while GL does have a few nice 'compatability' extensions.

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Which part of the vertex-transform / rasterization pipeline do you want to change?

Both OpenGL and D3D use x,y=-1,-1 for the lower left, and x,y=1,1 for the top right.

You can construct your projection matrices differently (concatenate with a "scale y by -1" matrix) if you want to flip that upside down.

After projection into NDC (-1 to 1 range). The viewport is used to convert into pixel coordinates. D3D's viewport coords do treat the upper left as the 0,0 origin. You can flip these with something like:
vp.y = renderTarget.height - vp.y - vp.height;

With texture coords, GL uses lower left origin and D3D uses upper left. Easy to flip with uv.y=1-uv.y;

D3D typically doesn't have options to adopt GL's conventions at the API level, while GL does have a few nice 'compatability' extensions.

 

well, I'm rendering a fullscreen quad, and the vertices are defined in ndc space

      vec3 ll( -1, -1, 0 );
      vec3 lr( 1, -1, 0 );
      vec3 ul( -1, 1, 0 );
      vec3 ur( 1, 1, 0 );
This way I don't need to multiply them w/ a matrix in the vertex shader. I wanted to display a texture, but it appeared upside down.
So I figured that I have two options, flip the window coords, or flip the texture coords, as you mentioned. I figured the window coords would be less painful smile.png
where do I set this? vp.y = renderTarget.height - vp.y - vp.height;
Edited by Yours3!f

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where do I set this? vp.y = renderTarget.height - vp.y - vp.height;

In your D3D11_VIEWPORT, but... that's just to convert the placement of your viewport rect from GL coords to D3D (or vice versa), it won't actually flip it vertically.

well, I'm rendering a fullscreen quad, and the vertices are defined in ndc space, but it appeared upside down.

That's because NDC is the same in GL/D3D, but tex-coords are flipped. So the right thing(tm) to do is to flip your texcoords.

Or as a quick fix, you can just flip your VS's position.y output variable, but that won't fix the same bug in other cases (e.g. when artists put a texture on a model, it will be vertically flipped between the two APIs...)
 
As an alternative real fix, you can flip all of your textures on disk or when loading them (D3D expects the top row of pixels to come first in the buffer, GL expects the bottom row of pixels to come first in the buffer...), and also flip all your projection matrices upside down in one of the APIs (so that render-targets get flipped as well as texture files -- D3D's NDC->pixel coordinate mapping is flipped vertically from GL's)... In shaders like that which don't use a projection matrix, you'd just multiply the VS's position.y output by -1.
This will have the same effect -- the texture data itself (and render-target data) will now be upside down, so there's no need to flip the texcoords any more.

 

Personally, I choose to use D3D's coordinate systems as the standard, and do all this flipping nonsense in GL only -- but vice versa works too.

 

[Edit]

BTW, layout(origin_upper_left) only modifies the pixel coordinate value that is seen by the fragment shader, it doesn't actually change the window coordinate system or the rasterization rules.

The ARB_clip_control extension allows you to actually use D3D window coordinates in GL (including finally fixing GL's busted NDC depth range)... however, it only exists in GL4.

Edited by Hodgman

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where do I set this? vp.y = renderTarget.height - vp.y - vp.height;

In your D3D11_VIEWPORT, but... that's just to convert the placement of your viewport rect from GL coords to D3D (or vice versa), it won't actually flip it vertically.

well, I'm rendering a fullscreen quad, and the vertices are defined in ndc space, but it appeared upside down.

That's because NDC is the same in GL/D3D, but tex-coords are flipped. So the right thing(tm) to do is to flip your texcoords.

Alternatively, you can just flip your VS's position.y output variable, but that won't fix the same bug in other cases (e.g. when artists put a texture on a model, it will be vertically flipped between the two APIs...)
 
Alternatively, you can flip all of your textures on disk or when loading them (D3D expects the top row of pixels to come first in the buffer, GL expects the bottom row of pixels to come first in the buffer...), and also flip all your projection matrices upside down in one of the APIs (so that render-targets get flipped as well as texture files -- D3D's NDC->pixel coordinate mapping is flipped vertically from GL's)... In shaders like that which don't use a projection matrix, you'd just multiply the VS's position.s output by -1.
This will have the same effect -- the texture data itself (and render-target data) will now be upside down, so there's no need to flip the texcoords any more.

 

Personally, I choose to use D3D's coordinate systems as the standard, and do all this flipping nonsense in GL only -- but vice versa works too.

 

[Edit]

BTW, layout(origin_upper_left) only modifies the pixel coordinate value that is seen by the fragment shader, it doesn't actually change the window coordinate system or the rasterization rules.

The ARB_clip_control extension allows you to actually use D3D window coordinates in GL (including finally fixing GL's busted NDC depth range)... however, it only exists in GL4.

 

 

awesome, thank you for the detailed explanation! :)
I think I'll go w/ the flipping tex coords on the CPU solution, it seems to me that this is the least painful :)

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