MandelbrotFast.java

/**
 * Faster implementation of Mandelbrot set with less detail.
 */
public class MandelbrotFast {
    private static final int WIDTH = 960;
    private static final int HEIGHT = 540;

    private static final int MAX_ITER = 200;  // Lower = faster

    // Complex plane bounds
    private static final double X_MIN = -2.5;
    private static final double X_MAX = 1.0;
    private static final double Y_MIN = -1.0;
    private static final double Y_MAX = 1.0;

    // Size of the block to draw instead of 1 pixel, higher = faster
    private static final int BLOCK = 4;

    private static double mapX(int px) {
        return X_MIN + px * (X_MAX - X_MIN) / WIDTH;
    }

    private static double mapY(int py) {
        return Y_MIN + py * (Y_MAX - Y_MIN) / HEIGHT;
    }

    private static int mandelbrotIterations(double cr, double ci) {
        double zr = 0, zi = 0;
        int count = 0;

        while (count < MAX_ITER) {
            double zr2 = zr * zr - zi * zi;
            double zi2 = 2 * zr * zi;

            zr = zr2 + cr;
            zi = zi2 + ci;

            if (zr * zr + zi * zi > 4.0)
                break;

            count++;
        }

        return count;
    }

    public static void main(String[] args) {
        StdDraw.setTitle("Fast Mandelbrot");
        StdDraw.setCanvasSize(WIDTH, HEIGHT);
        StdDraw.setXscale(0, WIDTH);
        StdDraw.setYscale(0, HEIGHT);

        for (int px = 0; px < WIDTH; px += BLOCK) {
            for (int py = 0; py < HEIGHT; py += BLOCK) {

                double cr = mapX(px);
                double ci = mapY(py);

                int iter = mandelbrotIterations(cr, ci);

                if (iter == MAX_ITER)
                    StdDraw.setPenColor(StdDraw.BLACK);
                else
                    StdDraw.setPenColor(StdDraw.WHITE);

                // Draw a filled block instead of a pixel
                StdDraw.filledRectangle(px, py, BLOCK / 2.0, BLOCK / 2.0);
            }
        }
    }
}