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// Coding Challenge #102: 2D Water Ripple - // Video: https://www.youtube.com/watch?v=BZUdGqeOD0w// Algorithm: https://web.archive.org/web/20160418004149/http://freespace.virgin.net/hugo.elias/graphics/x_water.htm let cols, rows, current = [], previous = [], damping = 0.99; function mouseDragged() { current[mouseX][mouseY] = 100 } function setup() { pixelDensity(1) createCanvas(600, 400,P2D) cols = width rows = height for (let i = 0; i < cols; i++) { current[i] = [] previous[i] = [] for (let j = 0; j < rows; j++) { current[i][j] = 0 previous[i][j] = 0 } } previous[100][100] = 255 } function draw() { background(0) loadPixels() for (let i = 1; i < cols - 1; i++) { for (let j = 1; j < rows - 1; j++) { current[i][j] = (previous[i - 1][j] + previous[i + 1][j] + previous[i][j - 1] + previous[i][j + 1] + previous[i - 1][j - 1] + previous[i - 1][j + 1] + previous[i + 1][j - 1] + previous[i + 1][j + 1] ) / 4 - current[i][j]; current[i][j] = current[i][j] * damping let index = (i + j * cols) * 4; pixels[index + 0] = current[i][j] * 255 pixels[index + 1] = current[i][j] * 255 pixels[index + 2] = current[i][j] * 255 pixels[index + 3] = 255 } } updatePixels() //swap buffers let temp = previous previous = current current = temp }</script>