Search Results

Search found 312 results on 13 pages for 'orbital mechanics'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 7/13 | < Previous Page | 3 4 5 6 7 8 9 10 11 12 13  | Next Page >

  • Need game development sandbox like Etoys to do 2D games prototyping

    - by Dimitry Tato
    I am new to game development, and currently working on development a mobile 2D game (for android). As the part of the development process, I need to build a prototype and playtest it, to see if the game mechanics and user interaction is ok For example: if I have a starship shooting at ememies, I need to see what's the best size for my starship. what trajectories should the enemy ships fly and what velocity. Should the enemy ships be coming only from left to right, or also from top Should the enemy ships form a 'flock' or just fly by themselves what's the best 'powerup' pickup mechanics: to shoot it, or to pick it with the ship etc Implementing these details directly in Java (Android) is time consuming and as many of the 'hypotheses' will be rejected, I also don't want to invest a lot of time to code thigs, majority of which gonna be rejected. I found 'tool' Etoys http://www.youtube.com/watch?v=34cWCnLC5nM&feature=related and official website http://www.squeakland.org/ which helps to build 'prototype' quickly, but Etoys is meant for children learning programming and is too basic. SO MY QUESTION IS: Is there any prototyping tool, as simple as Etoys and with better prototype quality?

    Read the article

  • A Guided Tour of Complexity

    - by JoshReuben
    I just re-read Complexity – A Guided Tour by Melanie Mitchell , protégé of Douglas Hofstadter ( author of “Gödel, Escher, Bach”) http://www.amazon.com/Complexity-Guided-Tour-Melanie-Mitchell/dp/0199798109/ref=sr_1_1?ie=UTF8&qid=1339744329&sr=8-1 here are some notes and links:   Evolved from Cybernetics, General Systems Theory, Synergetics some interesting transdisciplinary fields to investigate: Chaos Theory - http://en.wikipedia.org/wiki/Chaos_theory – small differences in initial conditions (such as those due to rounding errors in numerical computation) yield widely diverging outcomes for chaotic systems, rendering long-term prediction impossible. System Dynamics / Cybernetics - http://en.wikipedia.org/wiki/System_Dynamics – study of how feedback changes system behavior Network Theory - http://en.wikipedia.org/wiki/Network_theory – leverage Graph Theory to analyze symmetric  / asymmetric relations between discrete objects Algebraic Topology - http://en.wikipedia.org/wiki/Algebraic_topology – leverage abstract algebra to analyze topological spaces There are limits to deterministic systems & to computation. Chaos Theory definitely applies to training an ANN (artificial neural network) – different weights will emerge depending upon the random selection of the training set. In recursive Non-Linear systems http://en.wikipedia.org/wiki/Nonlinear_system – output is not directly inferable from input. E.g. a Logistic map: Xt+1 = R Xt(1-Xt) Different types of bifurcations, attractor states and oscillations may occur – e.g. a Lorenz Attractor http://en.wikipedia.org/wiki/Lorenz_system Feigenbaum Constants http://en.wikipedia.org/wiki/Feigenbaum_constants express ratios in a bifurcation diagram for a non-linear map – the convergent limit of R (the rate of period-doubling bifurcations) is 4.6692016 Maxwell’s Demon - http://en.wikipedia.org/wiki/Maxwell%27s_demon - the Second Law of Thermodynamics has only a statistical certainty – the universe (and thus information) tends towards entropy. While any computation can theoretically be done without expending energy, with finite memory, the act of erasing memory is permanent and increases entropy. Life & thought is a counter-example to the universe’s tendency towards entropy. Leo Szilard and later Claude Shannon came up with the Information Theory of Entropy - http://en.wikipedia.org/wiki/Entropy_(information_theory) whereby Shannon entropy quantifies the expected value of a message’s information in bits in order to determine channel capacity and leverage Coding Theory (compression analysis). Ludwig Boltzmann came up with Statistical Mechanics - http://en.wikipedia.org/wiki/Statistical_mechanics – whereby our Newtonian perception of continuous reality is a probabilistic and statistical aggregate of many discrete quantum microstates. This is relevant for Quantum Information Theory http://en.wikipedia.org/wiki/Quantum_information and the Physics of Information - http://en.wikipedia.org/wiki/Physical_information. Hilbert’s Problems http://en.wikipedia.org/wiki/Hilbert's_problems pondered whether mathematics is complete, consistent, and decidable (the Decision Problem – http://en.wikipedia.org/wiki/Entscheidungsproblem – is there always an algorithm that can determine whether a statement is true).  Godel’s Incompleteness Theorems http://en.wikipedia.org/wiki/G%C3%B6del's_incompleteness_theorems  proved that mathematics cannot be both complete and consistent (e.g. “This statement is not provable”). Turing through the use of Turing Machines (http://en.wikipedia.org/wiki/Turing_machine symbol processors that can prove mathematical statements) and Universal Turing Machines (http://en.wikipedia.org/wiki/Universal_Turing_machine Turing Machines that can emulate other any Turing Machine via accepting programs as well as data as input symbols) that computation is limited by demonstrating the Halting Problem http://en.wikipedia.org/wiki/Halting_problem (is is not possible to know when a program will complete – you cannot build an infinite loop detector). You may be used to thinking of 1 / 2 / 3 dimensional systems, but Fractal http://en.wikipedia.org/wiki/Fractal systems are defined by self-similarity & have non-integer Hausdorff Dimensions !!!  http://en.wikipedia.org/wiki/List_of_fractals_by_Hausdorff_dimension – the fractal dimension quantifies the number of copies of a self similar object at each level of detail – eg Koch Snowflake - http://en.wikipedia.org/wiki/Koch_snowflake Definitions of complexity: size, Shannon entropy, Algorithmic Information Content (http://en.wikipedia.org/wiki/Algorithmic_information_theory - size of shortest program that can generate a description of an object) Logical depth (amount of info processed), thermodynamic depth (resources required). Complexity is statistical and fractal. John Von Neumann’s other machine was the Self-Reproducing Automaton http://en.wikipedia.org/wiki/Self-replicating_machine  . Cellular Automata http://en.wikipedia.org/wiki/Cellular_automaton are alternative form of Universal Turing machine to traditional Von Neumann machines where grid cells are locally synchronized with their neighbors according to a rule. Conway’s Game of Life http://en.wikipedia.org/wiki/Conway's_Game_of_Life demonstrates various emergent constructs such as “Glider Guns” and “Spaceships”. Cellular Automatons are not practical because logical ops require a large number of cells – wasteful & inefficient. There are no compilers or general program languages available for Cellular Automatons (as far as I am aware). Random Boolean Networks http://en.wikipedia.org/wiki/Boolean_network are extensions of cellular automata where nodes are connected at random (not to spatial neighbors) and each node has its own rule –> they demonstrate the emergence of complex  & self organized behavior. Stephen Wolfram’s (creator of Mathematica, so give him the benefit of the doubt) New Kind of Science http://en.wikipedia.org/wiki/A_New_Kind_of_Science proposes the universe may be a discrete Finite State Automata http://en.wikipedia.org/wiki/Finite-state_machine whereby reality emerges from simple rules. I am 2/3 through this book. It is feasible that the universe is quantum discrete at the plank scale and that it computes itself – Digital Physics: http://en.wikipedia.org/wiki/Digital_physics – a simulated reality? Anyway, all behavior is supposedly derived from simple algorithmic rules & falls into 4 patterns: uniform , nested / cyclical, random (Rule 30 http://en.wikipedia.org/wiki/Rule_30) & mixed (Rule 110 - http://en.wikipedia.org/wiki/Rule_110 localized structures – it is this that is interesting). interaction between colliding propagating signal inputs is then information processing. Wolfram proposes the Principle of Computational Equivalence - http://mathworld.wolfram.com/PrincipleofComputationalEquivalence.html - all processes that are not obviously simple can be viewed as computations of equivalent sophistication. Meaning in information may emerge from analogy & conceptual slippages – see the CopyCat program: http://cognitrn.psych.indiana.edu/rgoldsto/courses/concepts/copycat.pdf Scale Free Networks http://en.wikipedia.org/wiki/Scale-free_network have a distribution governed by a Power Law (http://en.wikipedia.org/wiki/Power_law - much more common than Normal Distribution). They are characterized by hubs (resilience to random deletion of nodes), heterogeneity of degree values, self similarity, & small world structure. They grow via preferential attachment http://en.wikipedia.org/wiki/Preferential_attachment – tipping points triggered by positive feedback loops. 2 theories of cascading system failures in complex systems are Self-Organized Criticality http://en.wikipedia.org/wiki/Self-organized_criticality and Highly Optimized Tolerance http://en.wikipedia.org/wiki/Highly_optimized_tolerance. Computational Mechanics http://en.wikipedia.org/wiki/Computational_mechanics – use of computational methods to study phenomena governed by the principles of mechanics. This book is a great intuition pump, but does not cover the more mathematical subject of Computational Complexity Theory – http://en.wikipedia.org/wiki/Computational_complexity_theory I am currently reading this book on this subject: http://www.amazon.com/Computational-Complexity-Christos-H-Papadimitriou/dp/0201530821/ref=pd_sim_b_1   stay tuned for that review!

    Read the article

  • The penultimate audit trigger framework

    - by Piotr Rodak
    So, it’s time to see what I came up with after some time of playing with COLUMNS_UPDATED() and bitmasks. The first part of this miniseries describes the mechanics of the encoding which columns are updated within DML operation. The task I was faced with was to prepare an audit framework that will be fairly easy to use. The audited tables were to be the ones directly modified by user applications, not the ones heavily used by batch or ETL processes. The framework consists of several tables and procedures...(read more)

    Read the article

  • Ledge grab and climb in Unity3D

    - by BallzOfSteel
    I just started on a new project. In this project one of the main gameplay mechanics is that you can grab a ledge on certain points in a level and hang on to it. Now my question, since I've been wrestling with this for quite a while now. How could I actually implement this? I have tried it with animations, but it's just really ugly since the player will snap to a certain point where the animation starts.

    Read the article

  • Freshen the RTS genre

    - by William Michael Thorley
    This isn't really a question, but a request for feedback. RPS (Rock, Paper, Scissors) RTS (Real Time Strategy) Demo version is out: The game is simple. It is an RTS. Why has it been made? Many if not most RTS’s are about economy and large numbers of unit types. The genre hasn’t actually developed the gameplay drastically from the very first RTS’s produced, some lesson have been learned, but the games are really very similar to how they have always been. RPS brings new gameplay to the RTS genre. Through three means: • New combat mechanics: RPS has two unique modes (as well as the old favourite) of resolving weapon fire. These change how combat happens, and make application of the correct units vital to success. From this comes the requirement to run Intel on your enemies. • Fixed Resource Economy: Each player has a fixed amount of energy, This means that there is a definite end to the game. You can attrition your enemy and try to outlast them, or try to outspend your opponent and destroy them. There is a limit to how fast ships can be built, through the generation of construction blocks, but energy is the fast limit on economy. • Game Modes: Game modes add victory conditions and new game pieces. The game is overseen by a controller which literally runs the game. Games are no longer line them up, gun them down. This means that new tactics must be played making skirmish games fresh with novel tactics without adding huge amounts of new game units to learn. I’ve produced RPS from the ground. I will be running a kickstarter in the near future, but right now I want feedback and input from the game developing community. Regarding the concepts, where RPS is going, the game modes, the combat mechanics. How it plays. RPS will give fresh gameplay to the genre so it must be right. It works over the internet or a LAN and supports single player games. Get it. Play it. Tell me about your games. Thank you Demo: https://dl.dropbox.com/u/51850113/RPS%20Playtest.zip Tutorials: https://dl.dropbox.com/u/51850113/RPSGamePlay.zip

    Read the article

  • Change CSS EMs to Percentage Automatically.

    - by Zachary Brown
    I cheated on a small site I was working on and used a site builder (Web Dwarf by Virtual Mechanics) to save time. I didn't realize it at the time, but this builder specifies the width, height and positions using CSS EMs. Is there an automated tool out there that will read through the CSS and convert each EM to a percentage so it will display correctly on wide screens as well? Any help would be great! Thanks. Here is the CSS: http://pastebin.de/14055

    Read the article

  • How closely can a game resemble another game without legal problems

    - by Fuu
    The majority of games build on successes of other games and many are downright clones. So where is the limit of emulating before legal issues come into play? Is it down to literary or graphic work like characters and storyline that cause legal problems, or can someone actually claim to own gameplay mechanics? There are so many similar clone games out there that the rules are probably very slack or nonexistent, but I'd like to hear the views of more experienced developers / designers.

    Read the article

  • Oracle to SQL Server: Crossing the Great Divide, Part 1

    When a SQL expert moves from Oracle to SQL Server, he can spot obvious strengths and weaknesses in the product that aren't obvious to the SQL Server DBA. Jonathan Lewis is that man, as he records his train of thought whilst he investigates the mechanics of the database engine. The result makes interesting reading.

    Read the article

  • Post 12.04 Update, stuck on splash screen

    - by Lawrence
    I updated to 12.04 a couple of weeks ago and I haven't started up Ubuntu until now. On start up the computer gets stuck on the splash screen. I am a beginner in all of this linux mechanics. I've seen many people post about relatively the same problem but I have a hard time following. I am using Wubi and running it along side Windows Starter on a Toshiba netbook. Thanks for bearing with my unfamiliarity haha,

    Read the article

  • Oracle to SQL Server: Crossing the Great Divide, Part 1

    When a SQL expert moves from Oracle to SQL Server, he can spot obvious strengths and weaknesses in the product that are too familiar to be apparent to the SQL Server DBA. Jonathan Lewis is one such expert: In this article he records his train of thought whilst investigating the mechanics of the SQL Server database engine. The result makes interesting reading.

    Read the article

  • MMORPG game balancing

    - by Gary Paluk
    I've seen a couple of examples of some game balancing techniques in books yet they are not comprehensive and not particularly aimed at MMORPGs but I'm looking for practical examples of game balancing techniques for MMORPGs. I am interested to know if anyone has documented the techniques used in popular games with proven success in this area. Ideally, any resource would cover most common types of stats and include layman mathematical models or techniques used to balance game mechanics found in advanced MMORPGs (I know it's a cliché, but WoW style) Any help would be great!

    Read the article

  • Ideas for time-keeping in a webbased RPG?

    - by ashy_32bit
    I'm assigned a task of doing the preliminary research stuff for a web-based MMO RPG. Now my buggiest problem here is "web based" vs "MMO RPG". I did some research about time keeping systems and I'm totally confused as how exactly something as real-time as an MMO-RPG can work on some pull-only (unidirectional) platform like HTTP. I know there is also a turn-based alternative to time keeping but can it work in an MMO setting ? EDIT: Take a battle for example, player A (human) wants to attack Player B (also human) in the open. How does it work when when player A issues the "attack" command on player B ? how do I inform player B that he is being attacked ? and then how exactly the battle goes on between the two in an HTTP based communication channel? To my knowledge this is impossible unless you resort to another technology (HTML is 1-way, that is you can just ask server and get response, server can't update you unless being asked to. this is very well-known and simply explained). So I though maybe I can somehow change the whole timekeeping model from real-time to a more non-real-time model (towards a turn based RPG for example) and somehow work around the whole problem of "interactivity". EDIT2: It is not that I don't wanna use any server side technologies. For sure it is not gonna work client-side-only even for the most trivial of the multi-player games, let alone an RPG. So sure there would be a (probably complex) server side component to it (the so called Game Engine I suppose). The problem is not the technology that implements the logic (game mechanics) bits but the communication technology and how it limits the game mechanics abilities (like how real-time or turn based it is gonna be). HTTP is a request-response protocol meaning you get served only if you ask for it (explicitly send a GET or POST request to the server). HTTP server can not inform you if anything of interest happens in the game world unless you refresh the page (as some suggested) or you use some bi-directional tech (totally different animals) like Flash, WebSock, HTML5 etc etc. So maybe the question is: Is it possible to implement a MMORPG using only HTML5/PHP and no periodic page refreshes? if so what would be rules to make it an MMO-RPG? Can't explain it any clearer. Sorry :D

    Read the article

  • Book Readers As Envisioned Circa 1935

    - by Jason Fitzpatrick
    This early 20th century sketch showcases the future of books; thankfully the actual delivery of the concept proved to be a bit more lap-friendly. The sketch is from the April, 1935 issues of Everyday Science and Mechanics and presents a vision of book consumption that, thankfully, came to pass in a much more compact fashion that doesn’t require swapping rolls of film. [via Boing Boing] How To Properly Scan a Photograph (And Get An Even Better Image) The HTG Guide to Hiding Your Data in a TrueCrypt Hidden Volume Make Your Own Windows 8 Start Button with Zero Memory Usage

    Read the article

  • A Checklist of Current SEO Techniques

    Search engine optimization entail fine tuning a website's code alongside a thorough linking architecture and just like mechanics, use a checklist to track down what has already been accomplished and how to measure the effect of each step on all other variables. The following is a basic overview of the steps you should take to ensure you leave nothing to chance, anything that can have a positive effect on your website's ranking thus improve the amount of traffic.

    Read the article

  • Bring a Touch of the Wild West to Your Desktop with the Rango Theme for Windows 7

    - by Asian Angel
    Rango the chameleon has his hands full when he becomes the new sheriff in an Old West town called Dirt. Now you can bring his adventures to your desktop with this new theme from Microsoft. The theme comes with seven wallpapers featuring Rango, his new friends, and others he meets along the way. Download the Rango Windows 7 Theme [Windows 7 Personalization Gallery] Latest Features How-To Geek ETC Should You Delete Windows 7 Service Pack Backup Files to Save Space? What Can Super Mario Teach Us About Graphics Technology? Windows 7 Service Pack 1 is Released: But Should You Install It? How To Make Hundreds of Complex Photo Edits in Seconds With Photoshop Actions How to Enable User-Specific Wireless Networks in Windows 7 How to Use Google Chrome as Your Default PDF Reader (the Easy Way) Bring a Touch of the Wild West to Your Desktop with the Rango Theme for Windows 7 Manage Your Favorite Social Accounts in Chrome and Iron with Seesmic E.T. II – Extinction [Fake Movie Sequel Video] Remastered King’s Quest Games Offer Classic Gaming on Modern Machines Compare Your Internet Cost and Speed to Global Averages [Infographic] Orbital Battle for Terra Wallpaper

    Read the article

  • Google image Swirl - interactive information visualization

    - by skyde
    I have seen this image swirl effect on a visual thesaurus. Is there any open source code for this? Or research paper explaining how they made it. I don't care about the algorithm to match similar objects. I only am wondering about the effects. From what i understand they are called recursive orbital diagram. Screenshot: google Wonder Wheel google image swirl

    Read the article

  • Explaining odd sound effects during BSOD

    - by bizzz
    Hello, over the years of using Microsoft operating systems, I many times encountered the situation that I only now want to understand. When you get BSOD while listening to music, there is a short period of time (1-2 sec), when screen freezes and the last part of music is repeated several times, before everything falls into blue abyss. Today I became very curious about mechanics behind this situation - what makes that certain part of audio to loop? I beg you, kind sirs, to satisfy my curiosity.

    Read the article

  • Full & Last Lunar Eclipse Of 2010 On December 21st

    - by Kavitha
    A total and last eclipse of the Moon occurs during the early morning hours of December 21, 2010 (for observers in western North America and Hawaii, the eclipse actually begins on the evening of December 20). You can fully view the total lunar eclipse from North America, Greenland and Iceland. The beginning stages of the eclipse is visible in Western Europe and the later stages after moonrise is visible in Western Asia. Total Lunar Eclipse Timings According to NASA “The Moon’s orbital trajectory takes it through the northern half of Earth’s umbral shadow. Although the eclipse is not central, the total phase still lasts 72 minutes”. The timings of the major eclipse phases are listed below. Penumbral Eclipse Begins 05:29:17 UT Partial Eclipse Begins 06:32:37 UT Total Eclipse Begins 07:40:47 UT Greatest Eclipse 08:16:57 UT Total Eclipse Ends 08:53:08 UT Partial Eclipse Ends 10:01:20 UT Penumbral Eclipse Ends 11:04:31 UT The timings of the major eclipse phases are listed below.   Total Lunar Eclipse of December 21, 2010   Europe North America Pacific Event GMT AST EST CST MST PST AKST HST Partial Eclipse Begins: 06:33 am 02:33 am 01:33 am 12:33 am 11:33 pm* 10:33 pm* 09:33 pm* 08:33 pm* Total Eclipse Begins: 07:41 am 03:41 am 02:41 am 01:41 am 12:41 am 11:41 pm* 10:41 pm* 09:41 pm* Mid-Eclipse: 08:17 am 04:17 am 03:17 am 02:17 am 01:17 am 12:17 am 11:17 pm* 10:17 pm* Total Eclipse Ends: 08:53 am 04:53 am 03:53 am 02:53 am 01:53 am 12:53 am 11:53 pm* 10:53 pm* Partial Eclipse Ends: 10:01 am 06:01 am 05:01 am 04:01 am 03:01 am 02:01 am 01:01 am 12:01 am Note: * Event occurs on evening of December 20, 2010 In India the Total Lunar Eclipse will take place between 13:10:47 and 14:23:08 on December 21st 2010. Animation Of Total Lunar Eclipse ShadowsAndSubstance website has a beautiful flash animation of December 21 2010 Total Lunar Eclipse and you can view it here Image Credit : flickr/stargazer95050 This article titled,Full & Last Lunar Eclipse Of 2010 On December 21st, was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

    Read the article

  • Remastered King’s Quest Games Offer Classic Gaming on Modern Machines

    - by ETC
    If you were a fan of the King’s Quest series of adventure games from the 1980s and 1990s, you’ll be thrilled to see them remastered with enhanced graphics, polished voice acting, and more. Gaming studio AGD Interactive has been engaged in a multi-year project to remaster and freely release the classic King’s Quest games. They started with King’s Quest I in 2001, moved on to King’s Quest II, and just recently released King’s Quest III (see in the screenshot above). The gameplay for all three games is excellent and really captures the feel of the original games (with better graphics, quality voice acting, and adjustments made for modern computers). When you run the game you first get a small pre-launch console. There you can make adjusts to the game before launching it. We’d recommend you enable the pixel doubling filter. It make the game a little blockier (hey you are playing a 1980s remake!) but it fills up high resolution monitors more effectively. Hit up the link below to download King’s Quest Redux I-III free of charge for both Windows and Mac computers. King’s Quest Redux [AGD Interactive via @cbeust] Latest Features How-To Geek ETC Should You Delete Windows 7 Service Pack Backup Files to Save Space? What Can Super Mario Teach Us About Graphics Technology? Windows 7 Service Pack 1 is Released: But Should You Install It? How To Make Hundreds of Complex Photo Edits in Seconds With Photoshop Actions How to Enable User-Specific Wireless Networks in Windows 7 How to Use Google Chrome as Your Default PDF Reader (the Easy Way) Manage Your Favorite Social Accounts in Chrome and Iron with Seesmic E.T. II – Extinction [Fake Movie Sequel Video] Remastered King’s Quest Games Offer Classic Gaming on Modern Machines Compare Your Internet Cost and Speed to Global Averages [Infographic] Orbital Battle for Terra Wallpaper WizMouse Enables Mouse Over Scrolling on Any Window

    Read the article

  • E.T. II – Extinction [Fake Movie Sequel Video]

    - by Asian Angel
    It has been years since E.T. returned home and Elliot is all grown up now. But things are about to get a lot more interesting when E.T. returns to help save the Earth. The only problem is that the invaders are the people from E.T.’s own planet. Forget cute and cuddly…extinction is the name of the game in this well edited fake sequel trailer from YouTube user Robert Blankenheim. Warning: If you have fond, warm memories of the original E.T. movie, then you may want to skip this video. These extra-terrestrials are literally portrayed as pure, bloodthirsy evil. ET Sequel: “ET-X” (Extended Trailer) [via Geeks are Sexy] Latest Features How-To Geek ETC Should You Delete Windows 7 Service Pack Backup Files to Save Space? What Can Super Mario Teach Us About Graphics Technology? Windows 7 Service Pack 1 is Released: But Should You Install It? How To Make Hundreds of Complex Photo Edits in Seconds With Photoshop Actions How to Enable User-Specific Wireless Networks in Windows 7 How to Use Google Chrome as Your Default PDF Reader (the Easy Way) Manage Your Favorite Social Accounts in Chrome and Iron with Seesmic E.T. II – Extinction [Fake Movie Sequel Video] Remastered King’s Quest Games Offer Classic Gaming on Modern Machines Compare Your Internet Cost and Speed to Global Averages [Infographic] Orbital Battle for Terra Wallpaper WizMouse Enables Mouse Over Scrolling on Any Window

    Read the article

  • Do Not Optimize Without Measuring

    - by Alois Kraus
    Recently I had to do some performance work which included reading a lot of code. It is fascinating with what ideas people come up to solve a problem. Especially when there is no problem. When you look at other peoples code you will not be able to tell if it is well performing or not by reading it. You need to execute it with some sort of tracing or even better under a profiler. The first rule of the performance club is not to think and then to optimize but to measure, think and then optimize. The second rule is to do this do this in a loop to prevent slipping in bad things for too long into your code base. If you skip for some reason the measure step and optimize directly it is like changing the wave function in quantum mechanics. This has no observable effect in our world since it does represent only a probability distribution of all possible values. In quantum mechanics you need to let the wave function collapse to a single value. A collapsed wave function has therefore not many but one distinct value. This is what we physicists call a measurement. If you optimize your application without measuring it you are just changing the probability distribution of your potential performance values. Which performance your application actually has is still unknown. You only know that it will be within a specific range with a certain probability. As usual there are unlikely values within your distribution like a startup time of 20 minutes which should only happen once in 100 000 years. 100 000 years are a very short time when the first customer tries your heavily distributed networking application to run over a slow WIFI network… What is the point of this? Every programmer/architect has a mental performance model in his head. A model has always a set of explicit preconditions and a lot more implicit assumptions baked into it. When the model is good it will help you to think of good designs but it can also be the source of problems. In real world systems not all assumptions of your performance model (implicit or explicit) hold true any longer. The only way to connect your performance model and the real world is to measure it. In the WIFI example the model did assume a low latency high bandwidth LAN connection. If this assumption becomes wrong the system did have a drastic change in startup time. Lets look at a example. Lets assume we want to cache some expensive UI resource like fonts objects. For this undertaking we do create a Cache class with the UI themes we want to support. Since Fonts are expensive objects we do create it on demand the first time the theme is requested. A simple example of a Theme cache might look like this: using System; using System.Collections.Generic; using System.Drawing; struct Theme { public Color Color; public Font Font; } static class ThemeCache { static Dictionary<string, Theme> _Cache = new Dictionary<string, Theme> { {"Default", new Theme { Color = Color.AliceBlue }}, {"Theme12", new Theme { Color = Color.Aqua }}, }; public static Theme Get(string theme) { Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } return cached; } } class Program { static void Main(string[] args) { Theme item = ThemeCache.Get("Theme12"); item = ThemeCache.Get("Theme12"); } } This cache does create font objects only once since on first retrieve of the Theme object the font is added to the Theme object. When we let the application run it should print “Creating new font” only once. Right? Wrong! The vigilant readers have spotted the issue already. The creator of this cache class wanted to get maximum performance. So he decided that the Theme object should be a value type (struct) to not put too much pressure on the garbage collector. The code Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } does work with a copy of the value stored in the dictionary. This means we do mutate a copy of the Theme object and return it to our caller. But the original Theme object in the dictionary will have always null for the Font field! The solution is to change the declaration of struct Theme to class Theme or to update the theme object in the dictionary. Our cache as it is currently is actually a non caching cache. The funny thing was that I found out with a profiler by looking at which objects where finalized. I found way too many font objects to be finalized. After a bit debugging I found the allocation source for Font objects was this cache. Since this cache was there for years it means that the cache was never needed since I found no perf issue due to the creation of font objects. the cache was never profiled if it did bring any performance gain. to make the cache beneficial it needs to be accessed much more often. That was the story of the non caching cache. Next time I will write something something about measuring.

    Read the article

  • Compare Your Internet Cost and Speed to Global Averages [Infographic]

    - by ETC
    Internet pricing and speed varies wildly across the world. The US, for instance, currently ranks 15th in speed but enjoys reasonably priced internet access. How reasonably priced? If you’re a US citizen you likely have an average internet access speed of 4.8 mbps and you pay a little over $3 per mbps. If you’re in Sweden, however, you likely have an 18 mbps connection and you pay a scant 63 cents per mpbs. The real envy of the internet speed Olympics by far is Japan with a mighty 61 mbps at a mere 27 cents per mbps. Hit up the link below for the full infographic (or use this local mirror if you need to dodge a firewall), then sound off in the comments with how you compare on the international scale. Internet Speeds and Costs Around the World [via Daily Infographic] Latest Features How-To Geek ETC Should You Delete Windows 7 Service Pack Backup Files to Save Space? What Can Super Mario Teach Us About Graphics Technology? Windows 7 Service Pack 1 is Released: But Should You Install It? How To Make Hundreds of Complex Photo Edits in Seconds With Photoshop Actions How to Enable User-Specific Wireless Networks in Windows 7 How to Use Google Chrome as Your Default PDF Reader (the Easy Way) Manage Your Favorite Social Accounts in Chrome and Iron with Seesmic E.T. II – Extinction [Fake Movie Sequel Video] Remastered King’s Quest Games Offer Classic Gaming on Modern Machines Compare Your Internet Cost and Speed to Global Averages [Infographic] Orbital Battle for Terra Wallpaper WizMouse Enables Mouse Over Scrolling on Any Window

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 3 4 5 6 7 8 9 10 11 12 13  | Next Page >