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• ### 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:
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

• 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!

# OpenGL 3D rendering of bilinear surface patch

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## Recommended Posts

This may be the incorrect thread, and the subject may not describe my issue very well, but I ask that you bear with me. I'm currently working on a renderer for bilinear surface patches just as a fun little side project and I've currently got my algorithm spitting out a list of ordered vertices as the patch is sampled. I'm having a problem figuring out how best to reorder the vertices in to a vertex array for rendering as a 3D mesh. I know it's basically the same process as polygonizing a height map, however instead of one value for each point, I've got three and I'm not exactly sure the best way to render the data. When thrown straight in to an array and rendered as points using GL_POINT in OpenGL I get the desired shape of the surface patch (This would mostly likely work in DirectX as well so it's not an API dependent question), however it's not really 3D and it's a very bad way to render a vertex array and nothing can really be done with the data as there aren't any polygons. I've been thinking that reordering all the vertices in order to create triangle strips would be expensive so perhaps an index array would work, however I'm not sure how best to calculate the indices. Any help would be appreciated as this has been bugging me for days and I can't seem to see the answer or come up with a clean algorithm for reordering the vertices into triangle strips. For clarification in case it's necessary:
current vertex array:
x1, y1, z3, x2, y2, z3, x4, y4, z4, etc..

Need to reorder or index so that triangle strip looks something like:

(x1,y1,z1)--------(x2,y2,z2)-----------(x3,y3,z3)
|                  /|                     /
|                /  |                  /
|              /    |               /
|            /      |             /
|           /       |           /
(x4,y4,z4)/         (x5,y5,z5)/


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Indexed tri strips. see this for an example. The ParametricSurface.cpp file contains the code to do what you are after.

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Hi,

You should go with indexed triangle lists, using indexed triangle strips will just give you some extra head ache (need of degenerated triangles to join strips together).

You don't need to re-order any vertices, assuming that they are in a grid shape.

Here's a little example for the indexed tri-list:

The vertex layout:

0-1-2
|/|/|
3-4-5
|/|/|
6-7-8

The index buffer (put on different lines to show different triangles)

0,1,3,
1,3,4,
1,2,4,
2,4,5,
3,4,6,
4,7,6,
4,5,7,
5,8,7

I think that you should study the matter on the paper to find out the rule used here.

Good luck!

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RobTheBloke: Thanks for the source. I looked at it briefly and I'm not entirely sure it really helps as the vertices appear to already be assumed to be in the correct order unless I'm mistaken.

kauna:I have figured that an indexed array would probably be the best way to do what I'm after, however I'm not 100% sure how they work anymore as I tend to avoid them because they make normal calculations a bit less straightforward. From your example I would be doing something like this?:

vertexArray = {x1,y1,z1, x2,y2,z2, x3,y3,z3, x4,y4,z4}indexArray = {0,0,0, 1,1,1, 2,2,2, 1,1,1, 3,3,3, 2,2,2}Where the polygon looks like:P0-P1| / |P2-P3and is wound clockwise.

[Edited by - DerUnterMensch on January 30, 2008 1:57:58 PM]

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Quote:
 I have figured that an indexed array would probably be the best way to do what I'm after, but I can't really remember how to do indexed arrays and can't seem to find any of my books on either DirectX or OpenGL.

DirectX SDK (for example) should have examples about using indexed primitives.

Quote:
 When provided with an array of vertices the API looks for a single index for every three vertices in the vertex array? Or is it more complicated?

When using triangle list, the API reads 3 indices at a time from the index buffer and makes one triangle out of them (by using the vertices defined in the vertex buffer).

So, when defining triangle list the index buffer has three times as many indices as there is triangle primitives.

Quote:
 Regrettably even if I can find my books and refresh on index arrays, I've no idea how to calculate the indexes algorithmically as I want to be able to control the resolution of the patch on runtime so I can't simply work out the indexes and expect them not to change.

I am not sure what you are talking about. Are you trying to implement some sort of LOD algorithm?

If I am not totally mistaken about your question, the following code would do the work for you.

//Something like thisfor(int y = 0; y < NumVerticesY-1; ++y){for(int x = 0; x < NumVerticesX-1; ++x){    int Index = y * NumVerticesX;    *indices++ = Index;    *indices++ = Index+1;    *indices++ = Index+NumVerticesX;    *indices++ = Index+1;    *indices++ = Index+NumVerticesX;    *indices++ = Index+NumVerticesX+1;}}

Regards!

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Quote:
 Original post by DerUnterMenschkauna:I have figured that an indexed array would probably be the best way to do what I'm after, however I'm not 100% sure how they work anymore as I tend to avoid them because they make normal calculations a bit less straightforward.

Having index array shouldn't really affect the way you calculate your normals.

Quote:
 vertexArray = {x1,y1,z1, x2,y2,z2, x3,y3,z3, x4,y4,z4}indexArray = {0,0,0, 1,1,1, 2,2,2, 1,1,1, 3,3,3, 2,2,2}Where the polygon looks like:P0-P1| / |P2-P3

Your index array should look like:

indexArray = {0,1,2,1,3,2}

and usually vertices have more components than just position (such as normal, texture coordinates etc).

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Quote:
 ...and usually vertices have more components than just position (such as normal, texture coordinates etc).

I tend to send vertices, normals, and texture coordinates to the GPU in separate arrays. When I know the mesh isn't going to be messed with I try to package everything together, but repacking an array constantly for a program that changes the normals or texture coordinates every frame and doesn't touch the rest is a pest.

Quote:
 I am not sure what you are talking about. Are you trying to implement some sort of LOD algorithm?

At the moment I'm sampling the patch in increments to give me a 10x10 grid of points, but if I were to make it to were the program could sample more or less often the number of points would change. This would break most of the ways I can think of calculating the indices so that the grid would render as triangle strips as I can't simply say a polygon is vertexArray[x], vertexArray[x+1], and vertexArray[x+1*gridWidth] or something like that as the vertices are in groups of three and x would be the x coord, x+1 would be the y coord (not the x coord of the next point), and x+1*gridWidth would be something completely wrong.

Quote:
 If I am not totally mistaken about your question, the following code would do the work for you.

Perhaps this is exactly what I'm trying to do but I don't think so. I guess I'm just going to have to leave this unsolved and go back to basics as I seem to have allowed myself to forget way to much after I wrote my engine to do all this stuff for me (though I never did finish a model loader so I don't have any code relevant to this sort of problem, though an imported mesh is usually ordered correctly from the start, so that probably wouldn't help anyways).

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Hi,

I think that you are trying to do things a bit in hard way.

Quote:
 ...but repacking an array constantly for a program that changes the normals or texture coordinates every frame and doesn't touch the rest is a pest.

It is quite the same to change normals or texture coordinates was the data in vertex structures or in separate arrays. So, constant repacking shouldn't be needed.

Quote:
 At the moment I'm sampling the patch in increments to give me a 10x10 grid of points, but if I were to make it to were the program could sample more or less often the number of points would change.

It is perfectly ok to resample or recreate your patch vertices/indices if you want to present it in a different sampling resolution. In the case you are doing it very often so that it creates some significant overhead, then (and only then) you might consider a more complicated solutions.

However, I'd first work out the simple and working version, then do the profiling to see if it requires some optimisations.

As a programmer you'll need to define yourself the rules how your system works. For example, for triangulating a grid I have made a rule which works. Although it works only for grids, thats enough because it is only used with grids.

If you have just a bunch of vertices, there is absolutely no way to figure out the correct triangulation.

Cheers!

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Quote:
 Original post by DerUnterMenschRobTheBloke: Thanks for the source. I looked at it briefly and I'm not entirely sure it really helps as the vertices appear to already be assumed to be in the correct order unless I'm mistaken.

they are ordered as such

idx=0;for(i=0;i<divsu;++i){  for(int j=0;j<divsv;++j)  {    verts[idx] = evalAt(i,j);    ++idx;  }}

The tri strips then get generated as...

0       1       2            divsv-1|   /   |   /   |   /divsv+0 divsv+0 divsv+2 .... divsv+divsv-1

or something along those lines anyway.