;; Project:  A procedure is worth a thousand pictures
;; Alex Marrs and Kevin Jennison

;; Intent

In our picture, we intend to explore the use of repetition with polygons and lines to create an illusion of motion.  More specifically, we want to draw the concept the sound of jazz (we are using Cannonball Adderley's “Work Song” as inspiration). To do so, we will use shapes that move rhythmically across the picture plane.  Utilizing trigonometric functions to represent these physical phenomena, the aim is to capture the soul of jazz, as represented by our subject song.  To further explore the lively and sometimes harsh sounds of jazz, we will make our foreground colors warm so the positive shapes contrast with the coolly-colored backdrop.  One to five parallel lines will repeat throughout the picture as an allusion to music staves.


;; Techniques

In each image, we will vary the following:
-shape and number of sides of polygon (triangle, square, star, Honor G, etc.)
-the path that the repetitious polygons follow
-varied colors for each polygon, based on “n”
-varied colors of background elements based on “n”
-the magnitude and frequency of trigonometric functions 
-the position , length and number of music staves
-the background color

To create the rhythmic polygons, we will use direct numeric recursion and the GIMP painting tools.  The procedure will draw each polygon by using (image-select-polygon!) and filling the selection; subsequently, the procedure will select another polygon region by changing the positions of (image-select-polygon!).  The shape of each polygon will be stored as positions in a vector. 

The draw-sin procedure uses the user input “n” to vary the modulation of sine wave, as it decompresses over time.  Additionally, the height, axis and width can be used to corrupt and transform the sine wave into more interesting graphical patterns and shapes.  Because the draw-sin procedure draws each tiny segment of line, it is also easy to progressively vary the sine-wave's color, width, etc.  The draw-sin procedure uses direct numeric recursion to create the sine-wave within the desired width, by creating very small segments from point to point, where the position of the next point is determined by the numeric recursive element of the procedure.  By varying the distance of the offset and the magnitude of the sine function's product, we will create 0-3 sine waves per image, with varying frequency. We will also vary the color progressively of each sine wave in relativity to the background colors.

We will use image-draw-line and recursion to draw the staves.

The background color is determined where we divided the whole range of RGB values by 1000, and then determine which one to use as a function of input “n”. Thus, using this color as an input also for our sine waves, music staves and polygons we are able to create a thousand “unique” images by virtue of color alone. Additionally, there is the potential for 0-3 sine waves per image (4 possibilities), 1-5 lines (with 4 length possibilities, 4 height possibilities).  In addition, there are 4 polygon shapes and 3 polygon trajectories (equations).  The change in color between each polygon is different for each n.