Tw1ddle/geometrize-haxe

package geometrize.rasterizer;

/**
 * Represents a scanline, a row of pixels running across a bitmap.
 * @author Sam Twidale (https://samcodes.co.uk/)
 */
class Scanline {
    /**
     * The y-coordinate of the scanline.
     */
    public var y(default, null):Int;
    /**
     * The leftmost x-coordinate of the scanline.
     */
    public var x1(default, null):Int;
    /**
     * The rightmost x-coordinate of the scanline.
     */
    public var x2(default, null):Int;

    /**
     * Creates a new scanline.
     * @param    y    The y-coordinate.
     * @param    x1    The leftmost x-coordinate.
     * @param    x2    The rightmost x-coordinate.
     */
    public inline function new(y:Int, x1:Int, x2:Int) {
        //Sure.sure(x1 <= x2); // NOTE hot allocations, too expensive to check
        this.y = y;
        this.x1 = x1;
        this.x2 = x2;
    }
    
    /**
     * Crops the scanning width of an array of scanlines so they do not scan outside of the given area.
     * @param    scanlines    The scanlines to crop.
     * @param    w    The width to crop.
     * @param    h    The height to crop.
     * @return    Array of the cropped scanlines.
     */
    public static function trim(scanlines:Array<Scanline>, w:Int, h:Int):Array<Scanline> {
        Sure.sure(scanlines != null);
        
        return scanlines.filter(trimHelper.bind(_, w, h));
    }
    
    private static inline function trimHelper(line:Scanline, w:Int, h:Int):Bool {
        if (line.y < 0 || line.y >= h || line.x1 >= w || line.x2 < 0) {
            return false;
        }
        line.x1 = Util.clamp(line.x1, 0, w - 1);
        line.x2 = Util.clamp(line.x2, 0, w - 1);
        return (line.x1 <= line.x2);
    }
}