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RenderPolys.dart
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RenderPolys.dart
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library renderpolies;
import 'dart:html';
import 'dart:json';
import 'dart:math';
import 'package:box2d/box2d_browser.dart';
final WIDTH = 400;
final HEIGHT = 300;
final CENTER_X = 0;//WIDTH/2;
final CENTER_Y = 0;//HEIGHT/2;
String polys_json() {
return """
[
{
"points": [
{"x":${CENTER_X+50},"y":${CENTER_Y+50}},
{"x":${CENTER_X+50},"y":${CENTER_Y-50}},
{"x":${CENTER_X-50},"y":${CENTER_Y-50}},
{"x":${CENTER_X-50},"y":${CENTER_Y+50}}
]
},
{
"points": [
{"x":${CENTER_X+140},"y":${CENTER_Y+40}},
{"x":${CENTER_X+130},"y":${CENTER_Y-30}},
{"x":${CENTER_X+50},"y":${CENTER_Y-50}},
{"x":${CENTER_X+50},"y":${CENTER_Y+50}}
]
},
{
"points": [
{"x":${CENTER_X-50},"y":${CENTER_Y+40}},
{"x":${CENTER_X-50},"y":${CENTER_Y-20}},
{"x":${CENTER_X-100},"y":${CENTER_Y+80}}
]
}
]
""";
}
class MyPoly {
List<Vector> points;
MyPoly(this.points){}
}
class Page {
static final int border = 5;
Page(CanvasRenderingContext2D this.context) {
width_ = context.canvas.width;
height_ = context.canvas.height;
}
DrawPoly(List<Vector> points) {
assert(points.length>2);
context.lineWidth = 2;
context.fillStyle = 'cornflowerblue';
context.strokeStyle = 'darkblue';
context.beginPath();
context.moveTo(points[0].x, points[0].y);
for( var i=1; i<points.length; i++) {
context.lineTo(points[i].x, points[i].y);
}
context.fill();
context.closePath();
context.stroke();
}
Load(String polys_txt) {
minv = new Vector(double.INFINITY,double.INFINITY);
maxv = new Vector(-double.INFINITY,-double.INFINITY);
polys = new List<MyPoly>();
List<Map> parsed_polys = parse(polys_txt);
for( var parsed_poly in parsed_polys) {
var points = new List<Vector>();
assert(parsed_poly["points"].length>2);
for(Map v in parsed_poly["points"]) {
num x = v["x"];
num y = v["y"];
minv.x = min(minv.x, x);
maxv.x = max(maxv.x, x);
minv.y = min(minv.y, y);
maxv.y = max(maxv.y, y);
points.addLast(new Vector(x, y));
}
polys.add(new MyPoly(points));
}
print("minv: $minv");
print("maxv: $maxv");
}
void SetView(num x, num y, {num width, num height}) {
context.clearRect(0, 0, width_, height_);
context.setTransform(1, 0, 0, 1, 0, 0);
var w = width_/2;
var h = height_/2;
context.translate(w, h);
//context.translate(-x, -y);
var scale = width_/width;
print("scale: $scale");
//scale = 1;
context.scale(scale, -scale);
context.translate(-x, -y);
}
Draw() {
print("center: $center");
SetView(center_x, center_y, width: maxv.x-minv.x);
//SetView(0, 0, width: maxv.x-minv.x);
for( var poly in polys) {
DrawPoly( poly.points);
}
var count = 20;
var sep = 10;
var total = count * sep;
var nib = sep/2;
context
..lineWidth = 1
..strokeStyle = "black"
..beginPath()
..moveTo(total, 0)
..lineTo(-total, 0)
..moveTo(0, total)
..lineTo(0, -total)
..closePath()
..stroke();
for(int i = 1; i<=count; ++i) {
context
..lineWidth = .5
..strokeStyle = "red"
..beginPath()
//x right
..moveTo(i*sep, nib)
..lineTo(i*sep, -nib)
//x left
..moveTo(-i*sep, nib)
..lineTo(-i*sep, -nib)
//y top
..moveTo(nib, i*sep)
..lineTo(-nib, i*sep)
//y bottom
..moveTo(nib, -i*sep)
..lineTo(-nib, -i*sep)
..closePath()
..stroke();
}
context
..strokeStyle = "cyan"
..setTransform(1, 0, 0, 1, 0, 0)
..beginPath()
..moveTo(width_/2,0)
..lineTo(width_/2,height_)
..moveTo(0,height_/2)
..lineTo(width_,height_/2)
..closePath()
..stroke();
}
Vector get center => new Vector(center_x,center_y);
num get center_x => minv.x + (maxv.x-minv.x)/2;
num get center_y => minv.y + (maxv.y-minv.y)/2;
CanvasRenderingContext2D context;
List<MyPoly> polys;
Vector minv;
Vector maxv;
int width_;
int height_;
}
void main() {
query("#text").text = "Welcome to Dart!";
CanvasElement c = query("#canvas");
print(c.width);
var p = new Page(c.context2d);
p.Load(polys_json());
p.Draw();
}