com.github.mathiewz.slick.ibxm.Envelope Maven / Gradle / Ivy

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The main purpose of this libraryis to modernize and maintain the slick2D library.
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package com.github.mathiewz.slick.ibxm;

public class Envelope {
    public boolean sustain, looped;
    private int sustain_tick, loop_start_tick, loop_end_tick;
    private int[] ticks, ampls;

    public Envelope() {
        set_num_points(1);
    }

    public void set_num_points(int num_points) {
        if (num_points <= 0) {
            num_points = 1;
        }
        ticks = new int[num_points];
        ampls = new int[num_points];
        set_point(0, 0, 0);
    }

    /* When you set a point, all subsequent points are reset. */
    public void set_point(int point, int tick, int ampl) {
        if (point >= 0 && point < ticks.length) {
            if (point == 0) {
                tick = 0;
            }
            if (point > 0) {
                if (tick < ticks[point - 1]) {
                    /* Simple guess at where the point is supposed to be. */
                    tick += 256;
                }
                if (tick <= ticks[point - 1]) {
                    System.out.println("Envelope: Point not valid (" + tick + " <= " + ticks[point - 1] + ")");
                    tick = ticks[point - 1] + 1;
                }
            }
            ticks[point] = tick;
            ampls[point] = ampl;
            point += 1;
            while (point < ticks.length) {
                ticks[point] = ticks[point - 1] + 1;
                ampls[point] = 0;
                point += 1;
            }
        }
    }

    public void set_sustain_point(int point) {
        if (point < 0) {
            point = 0;
        }
        if (point >= ticks.length) {
            point = ticks.length - 1;
        }
        sustain_tick = ticks[point];
    }

    public void set_loop_points(int start, int end) {
        if (start < 0) {
            start = 0;
        }
        if (start >= ticks.length) {
            start = ticks.length - 1;
        }
        if (end < start || end >= ticks.length) {
            end = start;
        }
        loop_start_tick = ticks[start];
        loop_end_tick = ticks[end];
    }

    public int next_tick(int tick, boolean key_on) {
        tick = tick + 1;
        if (looped && tick >= loop_end_tick) {
            tick = loop_start_tick;
        }
        if (sustain && key_on && tick >= sustain_tick) {
            tick = sustain_tick;
        }
        return tick;
    }

    public int calculate_ampl(int tick) {
        int idx, point, delta_t, delta_a, ampl;
        ampl = ampls[ticks.length - 1];
        if (tick < ticks[ticks.length - 1]) {
            point = 0;
            for (idx = 1; idx < ticks.length; idx++) {
                if (ticks[idx] <= tick) {
                    point = idx;
                }
            }
            delta_t = ticks[point + 1] - ticks[point];
            delta_a = ampls[point + 1] - ampls[point];
            ampl = (delta_a << IBXM.FP_SHIFT) / delta_t;
            ampl = ampl * (tick - ticks[point]) >> IBXM.FP_SHIFT;
            ampl = ampl + ampls[point];
        }
        return ampl;
    }

    public void dump() {
        int idx, tick;
        for (idx = 0; idx < ticks.length; idx++) {
            System.out.println(ticks[idx] + ", " + ampls[idx]);
        }
        for (tick = 0; tick < 222; tick++) {
            System.out.print(calculate_ampl(tick) + ", ");
        }
    }
}