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    • 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 akshayMore
      I am trying to make a GeometryUtil class that has methods to draw point,line ,polygon etc. I am trying to make a method to draw circle.  
      There are many ways to draw a circle.  I have found two ways, 
      The one way:
      public static void drawBresenhamCircle(PolygonSpriteBatch batch, int centerX, int centerY, int radius, ColorRGBA color) { int x = 0, y = radius; int d = 3 - 2 * radius; while (y >= x) { drawCirclePoints(batch, centerX, centerY, x, y, color); if (d <= 0) { d = d + 4 * x + 6; } else { y--; d = d + 4 * (x - y) + 10; } x++; //drawCirclePoints(batch,centerX,centerY,x,y,color); } } private static void drawCirclePoints(PolygonSpriteBatch batch, int centerX, int centerY, int x, int y, ColorRGBA color) { drawPoint(batch, centerX + x, centerY + y, color); drawPoint(batch, centerX - x, centerY + y, color); drawPoint(batch, centerX + x, centerY - y, color); drawPoint(batch, centerX - x, centerY - y, color); drawPoint(batch, centerX + y, centerY + x, color); drawPoint(batch, centerX - y, centerY + x, color); drawPoint(batch, centerX + y, centerY - x, color); drawPoint(batch, centerX - y, centerY - x, color); } The other way:
      public static void drawCircle(PolygonSpriteBatch target, Vector2 center, float radius, int lineWidth, int segments, int tintColorR, int tintColorG, int tintColorB, int tintColorA) { Vector2[] vertices = new Vector2[segments]; double increment = Math.PI * 2.0 / segments; double theta = 0.0; for (int i = 0; i < segments; i++) { vertices[i] = new Vector2((float) Math.cos(theta) * radius + center.x, (float) Math.sin(theta) * radius + center.y); theta += increment; } drawPolygon(target, vertices, lineWidth, segments, tintColorR, tintColorG, tintColorB, tintColorA); } In the render loop:
      polygonSpriteBatch.begin(); Bitmap.drawBresenhamCircle(polygonSpriteBatch,500,300,200,ColorRGBA.Blue); Bitmap.drawCircle(polygonSpriteBatch,new Vector2(500,300),200,5,50,255,0,0,255); polygonSpriteBatch.end(); I am trying to choose one of them. So I thought that I should go with the one that does not involve heavy calculations and is efficient and faster.  It is said that the use of floating point numbers , trigonometric operations etc. slows down things a bit.  What do you think would be the best method to use?  When I compared the code by observing the time taken by the flow from start of the method to the end, it shows that the second one is faster. (I think I am doing something wrong here ).
      Please help!  
      Thank you.  
    • By CPPapprentice
      Hi Forum,
      in terms of rendering a tiled game level, lets say the level is 3840x2208 pixels using 16x16 tiles. which method is recommended;
      method 1- draw the whole level, store it in a texture-object, and only render whats in view, each frame.
      method 2- on each frame, loop trough all tiles, and only draw and render it to the window if its in view.
      are both of these methods valid? is there other ways? i know method 1 is memory intensive  but method 2 is processing heavy.
      thanks in advance
    • By wobes
      Hi there. I am really sorry to post this, but I would like to clarify the delta compression method. I've read Quake 3 Networking Model: http://trac.bookofhook.com/bookofhook/trac.cgi/wiki/Quake3Networking, but still have some question. First of all, I am using LiteNetLib as networking library, it works pretty well with Google.Protobuf serialization. But then I've faced with an issue when the server pushes a lot of data, let's say 10 players, and server pushes 250kb/s of data with 30hz tickrate, so I realized that I have to compress it, let's say with delta compression. As I understood, the client and server both use unreliable channel. LiteNetLib meta file says that unreliable packet can be dropped, or duplicated; while sequenced channel says that packet can be dropped but never duplicated, so I think I have to use the sequenced channel for Delta compression? And do I have to use reliable channel for acknowledgment, or I can just go with sequenced, and send the StateId with a snapshot and not separately? 
      Thank you. 
    • By dp304
      As far as I understand, the traditional approach to the architecture of a game with different states or "screens" (such as a menu screen, a screen where you fly your ship in space, another screen where you walk around on the surface of a planet etc.) is to make some sort of FSM with virtual update/render methods in the state classes, which in turn are called in the game loop; something similar to this:
      struct State { virtual void update()=0; virtual void render()=0; virtual ~State() {} }; struct MenuState:State { void update() override { /*...*/ } void render() override { /*...*/ } }; struct FreeSpaceState:State { void update() override { /*...*/ } void render() override { /*...*/ } }; struct PlanetSurfaceState:State { void update() override { /*...*/ } void render() override { /*...*/ } }; MenuState menu; FreeSpaceState freespace; PlanetSurfaceState planet; State * states[] = {&menu, &freespace, &planet}; int currentState = 0; void loop() { while (!exiting) { /* Handle input, time etc. here */ states[currentState]->update(); states[currentState]->render(); } } int main() { loop(); } My problem here is that if the state changes only rarely, like every couple of minutes, then the very same update/render method will be called several times for that time period, about 100 times per second in case of a 100FPS game. This seems a bit to make dynamic dispatch, which has some performance penalty, pointless. Of course, one may argue that a couple hundred virtual function calls per second is nothing for even a not so modern computer, and especially nothing compared to the complexity of the render/update function in a real life scenario. But I am not quite sure. Anyway, I might have become a bit too paranoid about virtual functions, so I wanted to somehow "move out" the virtual function calls from the game loop, so that the only time a virtual function is called is when the game enters a new state. This is what I had in mind:
      template<class TState> void loop(TState * state) { while (!exiting && !stateChanged) { /* Handle input, time etc. here */ state->update(); state->render(); } } struct State { /* No update or render function declared here! */ virtual void run()=0; virtual ~State() {} }; struct MenuState:State { void update() { /*...*/ } void render() { /*...*/ } void run() override { loop<MenuState>(this); } }; struct FreeSpaceState:State { void update() { /*...*/ } void render() { /*...*/ } void run() override { loop<FreeSpaceState>(this); } }; struct PlanetSurfaceState:State { void update() { /*...*/ } void render() { /*...*/ } void run() override { loop<PlanetSurfaceState>(this); } }; MenuState menu; FreeSpaceState freespace; PlanetSurfaceState planet; State * states[] = {&menu, &freespace, &planet}; void run() { while (!exiting) { stateChanged = false; states[currentState]->run(); /* Runs until next state change */ } } int main() { run(); } The game loop is basically the same as the one before, except that it now exits in case of a state change as well, and the containing loop() function has become a function template.
      Instead of loop() being called directly by main(), it is now called by the run() method of the concrete state subclasses, each instantiating the function template with the appropriate type. The loop runs until the state changes, in which case the run() method shall be called again for the new state. This is the task of the global run() function, called by main().
      There are two negative consequences. First, it has become slightly more complicated and harder to maintain than the one above; but only SLIGHTLY, as far as I can tell based on this simple example. Second, code for the game loop will be duplicated for each concrete state; but it should not be a big problem as a game loop in a real game should not be much more complicated than in this example.
      My question: Is this a good idea at all? Does anybody else do anything like this, either in a scenario like this, or for completely different purposes? Any feedback is appreciated!
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Very Basic Optimisation (pre or post increment)

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Hi, probably a very stupid question but anyway:

My lecturer told me that this "++i" is faster than "i++" when incrementing a for loop. Can anybody argue this point?

And if it's true, could you possibly explain why it's faster? 


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It depends on the type of i. If i is an integer, your compiler will likely generate the exact same code either way. If i is a complex type like an iterator with range checking, then ++i may be faster. Basically, ++i just increments i. i++ requires a copy to be made of i and then the object is incremented before returning the old copy. For integers, its very easy for the compiler to realize that the copy doesn't matter. For complex type it may or may not be able to decide that. 

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I've noticed that the VS compiler tends to be more aggressive about eliding the copy when it's the "iterate" argument of a for loop. I don't remember what version it was that I was looking at, though.

It's not a bad habit to just use the prefix operator when you're not capturing the result, though.

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I've never seen a case where ++i was slower than i++.  At worst case they're equal.  So until I see otherwise in a profiler I always use ++i.

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