An online collaborative art playground.
The canvas is divided into Cells. Each cells is controlled by one small JavaScript agent, that paints to the pixels in that cell. Agents can read from the previous state of their own cell, their neighbour's cells, or some external world signals to alter their behaviour and do something interesting.
An agent must have the following functions:
function setup(t, cell) {
}
function draw(t, cell, signals) {
}
The parameters are as follows:
t, the current time in seconds as a floating point number. Use this to change over time in a predicatable fashion. You can't make any assumptions about the absolute value of this number, only the relative difference between two calls.cell, a cell object representing the cell the agent is supposed to draw itself in. The methods of the cell object are described below.signals, an object with "signals" from the outside world that the agent can respond to.
new Color(r, g, b), create a new color with the given r, g, b values.clip(x, low, hi), constrain the value of x to be betweenlowandhi.dist(x0, y0, x1, y0), calculate the distance between two points.
The coordinate space of a cell ranges from (0, 0) in its top-left corner to
(cell.w, cell.h) in its bottom right corner. All coordinates are of the form
(x, y).
Functions on the Cell object:
cell.w,cell.h, the dimensions of the cell.cell.get(x, y), returns a Color objects of the current cell in the previous frame. May go outside the cell (i.e., coordinates < 0 or larger than the cell bounds will return values from neighbouring cells).cell.set(x, y, color), set the indicated pixel to the given color in the current frame.cell.rect(x, y, w, h, color), fill a rectangle in the cell.cell.fill(color), fill the entire cell with a color.
The signals object contains other signals than the values of the adjacent
cells.
cell.dist, 0..100, distance to distance sensor.cell.btn, 0 or 100, whether the button is pressed.cell.light, 0..100, the light sensor.cell.sound, 0..100, loudness measured on the sound sensor.cell.mouse.x,cell.mouse.y, location of the mouse cursor with respect to the top-left corner of the cell.cell.mouse.click, 0, 1 or 2, if the mouse button is pressed.
new Color(r, g, b), constructor.color.r,color.g,color.b, fields for the Red, Green, Blue components.color.mix(other, frac), mix two colors. Fraction should be in the range0..1.color.avg(), return the average of all R, G, B fields (interpret as grayscale).color.inv(), invert the color.color.scale(a), scale the color with the given factor (multiply all components witha).color.add(other),color.sub(other), add or subtract other color.
Note: You can try to work with HSV colors, but I've found that doing that for every pixel becomes waaaaay too slow. So don't do that :).