AphasiaWeb Fixes
I’ve fixed a few more lingering bugs or incomplete features on our AphasiaWeb project: Videos not working. The video files were not getting to the database insert function. The cause? On the client, I was writing to post.videoPath the URL after the upload finished, but I was reading from post.videoURL. Switching both to use post.videoURL […]
A C Interpreter
My programming languages class this semester will begin with a few lectures on shell scripting. As an exercise for myself, I thought I’d write a little C “interpreter” so that I can “directly” run my C source code. The first thing we’ll need is a C source file. Here’s one: Now, I need to indicate […]
Taming jQuery
In our AphasiaWeb project, I’ve run into a few problems that deserve some mention. jQuery.load and Caching We have several places in our code where we retrieve content from the server with a jQuery.load() call: I was finding that after adding posts, new content failed to show up. It appeared that load() wasn’t being called. […]
Generating utterance WAVs
I’m going to ask my students to write some C code to create an audio pronunciation of a number. For instance, 137 is pronounced “one hundred thirty-seven.” As input, I will give them WAV files containing the separated pronunciations of all the number words that are needed. They’ll need to read these files in, concatenate […]
A texture renderer on the Raspberry Pi
A collaborator is working on using a cluster of Raspberry Pis to build a multi-monitor display wall. We’re using textures in OpenGL to blit each frame across the display. For his benefit, I pieced together a simple texture renderer, where the texture is procedurally generated by XORing the texel indices. XOR textures are interesting: The […]
Blender 3-D View Pivot Point
Rotating the 3-D view in Blender sometimes behaves strangely. The pivot point seems to lie somewhere between me and the screen, making it very difficult to manipulate the view. The fix is to change the pivot point. Options include: Numpad . to pivot around the selection’s center. Shift C to pivot around the 3-D cursor.
SIGITE 2012
In October I had the good pleasure to visit Calgary, just east of the Canadian Rockies. The purpose of my visit was to present a paper on Paul Wagner’s MOBILE project. We wrote this paper not certain where to publish it. In our literature readings, we noticed much related work came from SIGITE. It was […]
Right-handed Coordinate System
The definitions of left- and right-handed coordinate systems never clear anything up for me. Following is my current understanding of how the systems are determined and why they are given their names. A right-handed coordinate system is one that can be modeled on your right hand. Point your index finger along the positive x-axis ([1 0 […]
Zooming to Target Rectangle
A student of mine was telling me about a sticky note app he was working on. When he tapped on a note, he wanted to animate its filling the screen. The drawing library we’re using supports all the standard transformations and includes the ability to set the pivot point about which scaling and rotation occur. […]
Computer Graphics Proofs
Inverse of rotation/translation matrix Occasionally I need to be back out of eye space and get back to object space, so I need the inverse of my modelview matrix. Finding an arbitrary inverse is non-trivial, but finding the inverse of a matrix that simply rotates and translates is simpler. Inverting a matrix product Inverting a […]