var mouse_dragging = false;
var last_mouse_down = null;
var mouse_loc = null;
var MIN_DRAG_DIST = 10;
var POINT_HIGHLIGHT_DIST = 10;
var LINE_HIGHLIGHT_DIST = 15;

var MOTION_SPEED_BASE =  2.8;

var selected_points = [];
var selected_lines = [];

var msg = //"3D drawing tool\n\n" +
          "Select     Left Click\n" +
		  "Rotate     Right Click\n" +
		  "Move       wasd, qe\n" +

    
function changeVelocity(direction, positive, state, lastState){
    if(state == 0){
        state = lastState;
        positive = !positive; }  // reverse the velocity
    
    var delta = Math.pow(2, state - 1) * max_move_delta / frame_rate;
    var delta = Math.pow(MOTION_SPEED_BASE, state - 1) * max_move_delta / frame_rate;
    if(!positive) delta = -delta;
    
    var velocityChange = [0, 0, 0];
    velocityChange[direction] = delta;
    vector_add(delta_position, velocityChange, delta_position); }
    

       var pt = point_projections[k];
       if(pt) ctx.fillRect(pt[0] - 2, pt[1] - 2, 4, 4); }
        
	//
	//  The following drawing of axes is to help provide an perspective
	//  The nuances of this draw behavior are created to provide visual cues for interpreting perspective and depth.
	//  
	//  Because we use a 2d canvas library for the drawing the rest of the points/shapes after projection, these visual information nuances are important.
	//

	// axis lines and dots
	ctx.beginPath();
	
    var faxis_pt = project(canvas, vector_add(origin, [0, 0, forward_axis_size]), view_transform, origin);
	var vaxis_pt = project(canvas, vector_add(origin, [0, -vertical_axis_size, 0]), view_transform, origin);
	
	ctx.fillStyle = "rgba(0,0,0,0.9)";
	ctx.fillStyle = "rgba(0,0,0,1.0)";
	
	var dot = vector_dot(view_transform[2], [0, 0, 1]);
	var r = 3.2 - 1.8 * dot;
	var fdot = vector_dot(view_transform[2], [0, 0, 1]);
	var fr = 4 - 2.5 * fdot;
	var vdot = vector_dot(view_transform[2], [0, -1, 0]);
	var vr = 4 - 2.5 * vdot;
	
	ctx.lineWidth = 1.333;
	ctx.beginPath();
	
	if(fdot >=0 && faxis_pt){ // occlude this axis, draw first
		ctx.moveTo(w/2, h/2);
		ctx.lineTo(faxis_pt[0], faxis_pt[1]);	
		ctx.fillRect(faxis_pt[0] - fr/2, faxis_pt[1] - fr/2, fr, fr); }
	if(dot < 0){  // draw red square first to partially occlude with axes
		ctx.fillStyle = "rgba(250, 0, 0, 0.9)";
		ctx.fillRect(w/2 - 2, h/2 - 2, 4, 4); }
		
	if(vdot >=0 && vaxis_pt){ // occlude this axis, draw first
		ctx.moveTo(w/2, h/2);
		ctx.lineTo(vaxis_pt[0], vaxis_pt[1]);	
		ctx.fillRect(vaxis_pt[0] - vr/2, vaxis_pt[1] - vr/2, vr, vr); }
	
	ctx.stroke()
	
		
	// draw center red square
	ctx.fillStyle = "rgba(250, 0, 0, 1.0)";
	ctx.fillRect(w/2 - 3, h/2 - 3, 6, 6);
		
	ctx.fillStyle = "rgba(0,0,0,0.9)";
	ctx.fillStyle = "rgba(0,0,0,1.0)";
	ctx.beginPath();
	
	if(faxis_pt){
	if(fdot < 0 && faxis_pt){
		ctx.moveTo(w/2, h/2);
		ctx.lineTo(faxis_pt[0], faxis_pt[1]);	
		ctx.fillRect(faxis_pt[0] - r/2, faxis_pt[1] - r/2, r, r); }
		ctx.fillRect(faxis_pt[0] - fr/2, faxis_pt[1] - fr/2, fr, fr); }
		
	if(vaxis_pt){
	if(vdot < 0 && vaxis_pt){
		ctx.moveTo(w/2, h/2);
		ctx.lineTo(vaxis_pt[0], vaxis_pt[1]);
		ctx.fillRect(vaxis_pt[0] - 2, vaxis_pt[1] - 2, 4, 4); }
		ctx.fillRect(vaxis_pt[0] - vr/2, vaxis_pt[1] - vr/2, vr, vr); }
	
	ctx.stroke();
	
	if(dot >= 0){  // draw red square last so it is not occluded by axes
		ctx.fillStyle = "rgba(250, 0, 0, 0.9)";
		ctx.fillRect(w/2 - 2, h/2 - 2, 4, 4); }
		

	// reset line width
	ctx.lineWidth = 1;