euglena/src/Triangle.java

import processing.core.*;
import static processing.core.PApplet.*;


class Triangle {
    float point1x, point1y, point2x, point2y, point3x, point3y;
    int color, brushSize;
    boolean visible;

    private boolean point1complete, point2complete;

    Triangle(int color, int penWidth) {
        this.color = color;
        this.brushSize = penWidth;
        this.visible = false;

        this.point1complete = false;
        this.point2complete = false;
    }

    Triangle(float point1x, float point1y, float point2x, float point2y,
             float point3x, float point3y, int color, int penWidth) {
        this.point1x = point1x;
        this.point1y = point1y;
        this.point2x = point2x;
        this.point2y = point2y;
        this.point3x = point3x;
        this.point3y = point3y;

        this.color = color;
        this.brushSize = penWidth;
        this.visible = true;

        this.point1complete = true;
        this.point2complete = true;
    }

    ProjectorCommand drawCommand() {
        return (ProjectorApplet p) -> {
            if (!visible) {
                //done drawing already
                return true;
            }

            float old_strokeWeight = p.g.strokeWeight;
            int old_strokeColor = p.g.strokeColor;

            p.strokeWeight(brushSize);
            p.stroke(color);
            p.noFill();

            p.triangle(p.convertXCoord(point1x), p.convertYCoord(point1y),
                    p.convertXCoord(point2x), p.convertYCoord(point2y),
                    p.convertXCoord(point3x), p.convertYCoord(point3y));

            p.strokeWeight(old_strokeWeight);
            p.stroke(old_strokeColor);
            return true;
        };
    }

    ClickGetter makeClickGetter(ProjectorApplet p) {
        return (int x, int y) -> {
            if (!point1complete){
                point1x = x;
                point1y = y;
                point1complete = true;
                return false;

            } else if (!point2complete) {
                point2x = x;
                point2y = y;
                point2complete = true;
                return false;

            } else {
                point3x = x;
                point3y = y;
                visible = true;

                p.commandQueue.add(drawCommand());
                return true;
            }
        };
    }
}