Tutorial by Examples: s

Uniforms

Uniforms are per program state. Every shader program has its own uniform state and its own locations.

webgl • State

Texture units are global state. If they were implemented in JavaScript they would look something like this // pseudo code gl = { activeTextureUnit: 0, textureUnits: [ { TEXTURE_2D: ?, TEXTURE_CUBE_MAP: ? }, { TEXTURE_2D: ?, TEXTURE_CUBE_MAP: ? }, { TEXTURE_2D: ?, TEXTURE_CUBE_...

webgl • State

Product collection - with attributes

//all attributes $collection = Mage::getModel('catalog/product') ->getCollection() ->addAttributeToSelect('*'); //specific attributes $collection = Mage::getModel('catalog/product') ->getCollection() ->addAttributeToSelect('name'); //certain attributes are special...

magento • Get Products from Database

Check if the product was correctly loaded

$productFound = ($product->getId() !== null)

magento • Get Products from Database

Using the revert command to discard unwanted changes.

The revert command allows discarding unwanted uncommitted changes. Reverting changes to a single file. hg revert example.c Reverting all changes. This will discard all changes not just the current directory. hg revert --all hg will output which files were reverted. reverting exa...

mercurial • Common operations

Features of Tcl

Cross Platform Portability Runs on Windows, Mac OS X, Linux, and virtually every variant of unix. Event driven programming Trigger events based on variable read / write / unset. Trigger events when a command is entered or left. Trigger events when a I/O channel (file or network) becom...

tcl • Getting started with tcl

Primitive to Primitive conversion table

ValueConverted To StringConverted To NumberConverted To Booleanundefinded"undefined"NaNfalsenull"null"0falsetrue"true"1false"false"0NaN"NaN"false"" empty string0false" "0true"2.4" (numeric)2.4true"test" (non nu...

JavaScript • Variable coercion/conversion

Deleting a derived object via a pointer to a base class that doesn't have a virtual destructor.

class base { }; class derived: public base { }; int main() { base* p = new derived(); delete p; // The is undefined behavior! } In section [expr.delete] §5.3.5/3 the standard says that if delete is called on an object whose static type does not have a virtual destructor: if the...

C++ • Undefined Behavior

Avoiding duplication of code in const and non-const getter methods.

In C++ methods that differs only by const qualifier can be overloaded. Sometimes there may be a need of two versions of getter that return a reference to some member. Let Foo be a class, that has two methods that perform identical operations and returns a reference to an object of type Bar: class ...

C++ • const keyword

Create a custom in-app keyboard

This is a basic in-app keyboard. The same method could be used to make just about any keyboard layout. Here are the main things that need to be done: Create the keyboard layout in an .xib file, whose owner is a Swift or Objective-C class that is a UIView subclass. Tell the UITextField to use t...

iOS • Managing the Keyboard

Use git send-email with Gmail

Background: if you work on a project like the Linux kernel, rather than make a pull request you will need to submit your commits to a listserv for review. This entry details how to use git-send email with Gmail. Add the following to your .gitconfig file: [sendemail] smtpserver = smtp.googlema...

Git • git send-email

When to use a Static variable

A Static variable declared locally is not destructed and does not lose its value when the Sub procedure is exited. Subsequent calls to the procedure do not require re-initialization or assignment although you may want to 'zero' any remembered value(s). These are particularly useful when late bindin...

VBA • Declaring Variables

Infinite Streams via Recursion

Streams can be built that reference themselves and thus become infinitely recursive. // factorial val fact: Stream[BigInt] = 1 #:: fact.zipWithIndex.map{case (p,x)=>p*(x+1)} fact.take(10) // (1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880) fact(24) // 620448401733239439360000 // the ...

Scala Language • Streams

List files and folders

To list files and folders inside current directory, we use ls command: user@host:/$ ls bin boot cdrom dev etc home initrd.img lib lib64 lost+found media mnt opt proc root run sbin srv sys tmp usr var vmlinuz ls prints folder structure in simple view, color coded by type....

Ubuntu • Basic Terminal commands

Animate at a specified interval (add a new rectangle every 1 second)

This example adds a new rectangle to the canvas every 1 second (== a 1 second interval) Annotated Code: <!doctype html> <html> <head> <style> body{ background-color:white; } #canvas{border:1px solid red; } </style> <script> window.onload=(functio...

html5-canvas • Animation

Animate at a specified time (an animated clock)

This example animates a clock showing the seconds as a filled wedge Annotated Code: <!doctype html> <html> <head> <style> body{ background-color:white; } #canvas{border:1px solid red; } </style> <script> window.onload=(function(){ // canva...

html5-canvas • Animation

Use requestAnimationFrame() NOT setInterval() for animation loops

requestAnimationFrame is similar to setInterval, it but has these important improvements: The animation code is synchronized with display refreshes for efficiency The clear + redraw code is scheduled, but not immediately executed. The browser will execute the clear + redraw code only when the d...

html5-canvas • Animation

Animate an image across the Canvas

This example loads and animates and image across the Canvas Important Hint! Make sure you give your image time to fully load by using image.onload. Annotated Code <!doctype html> <html> <head> <style> body{ background-color:white; } #canvas{border:1px solid re...

html5-canvas • Animation

Don't draw animations in your event handlers (a simple sketch app)

During mousemove you get flooded with 30 mouse events per second. You might not be able to redraw your drawings at 30 times per second. Even if you can, you're probably wasting computing power by drawing when the browser is not ready to draw (wasted == across display refresh cycles). Therefore it m...

html5-canvas • Animation

Working with Varargs parameters

Using varargs as a parameter for a method definition, it is possible to pass either an array or a sequence of arguments. If a sequence of arguments are passed, they are converted into an array automatically. This example shows both an array and a sequence of arguments being passed into the printVar...

Java Language • Varargs (Variable Argument)