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Report on Pure Data and Gem -----Tong Xu

Ⅰ . Introduction of Project on Pure Data and Gem

PD is a real-time graphical programming environment for audio, video,

and graphical processing. I was, and am in favor of it when I got in

touch with it on the class. It was fantastic when I watched the PD

patches were adopted to control the camera, or make various kinds of

sounds, or even form a control chain that all the classmates were

involved! However, compared with other modules, I found least

learning materials on PD, so it took me longer time on understanding

and performing PD patches. Just because of this, I will work on it to

supplement and translate more materials to people in China.

Personally using PD to control audio and video, though interesting, is

beyond my comprehension. So in my PD project, I took advantage of

Gem to perform graphical processing in Pure Data. And for the

dissertation project, I prefer to adopt Logic Pro to make background

music for three-dimensional chatting.

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To make this project more interactive, I added more interactive features,

including adding a light to the object, allowing users to rotate it, and

three colors are provided to change.

Ⅱ The Explanation of the Project—Color and Light

● The “gemwin” was made at the beginning in PD patch because it

controlled the window manager. It passed various messages to the

manager, controlling the attributes of the window. Then, I made a

message “create” to create Gem-window, and a message “destroy”

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to close the Gem-window. Messages “1” and “0” were used to turn

on or off the rendering.

● The “gemhead” was also necessary as it connected the gem objects

to the window manager. The start of any gemList began with the

gemhead.

● Then I thought of adding a point-light to the scene. The

non-geometric object “world_light” was created to produce a light

which was at an infinite distance from the scene, as the sun. It was

connected to be previously-made object “gemhead”. Consequently,

“lighting 0” and “lighting 1” were set up to give messages of “not

receive the light” and “receive the light” to gemwin.

● Then I adjusted the light with “rotate”. It was built as a

manipulation object and accepted a gemList that began with

“gemhead”. A number box was connected to “rotate” to display the

rotation amount. Users are allowed to click on the number box and

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drag upward or downward to change the value continuously.

● Another manipulation object “color” was then made to set colors of

all subsequent shape and vertex operations until reset by another

color. In the project, there were three colors provided, ie, green,

grey and yellow.

Ⅲ .Now, the project of Pure Data--- Color and Light

has been finished. I am always excited whenever I

play with it, and hope you will enjoy too!