remove demo game

util.geometry.go

@@ -0,0 +1,79 @@
+package pncdsl
+
+import "math"
+
+type Point struct {
+	X, Y float64
+}
+
+func (p Point) Add(q Point) Point { return Point{p.X + q.X, p.Y + q.Y} }
+func (p Point) Sub(q Point) Point { return Point{p.X - q.X, p.Y - q.Y} }
+func (p Point) Dist(q Point) float64 {
+	dx, dy := p.X-q.X, p.Y-q.Y
+	return math.Sqrt(dx*dx + dy*dy)
+}
+
+// Shape is a hotspot area. Rectangle and Polygon both satisfy it.
+type Shape interface {
+	Contains(p Point) bool
+	Bounds() Rectangle
+}
+
+type Rectangle struct {
+	X, Y, W, H float64
+}
+
+func Rect(x, y, w, h float64) Rectangle { return Rectangle{X: x, Y: y, W: w, H: h} }
+
+func (r Rectangle) Contains(p Point) bool {
+	return p.X >= r.X && p.X < r.X+r.W && p.Y >= r.Y && p.Y < r.Y+r.H
+}
+
+func (r Rectangle) Bounds() Rectangle { return r }
+
+func (r Rectangle) Center() Point { return Point{X: r.X + r.W/2, Y: r.Y + r.H/2} }
+
+type Polygon struct {
+	Points []Point
+}
+
+func Poly(pts ...Point) Polygon { return Polygon{Points: pts} }
+
+func (g Polygon) Contains(pt Point) bool {
+	n := len(g.Points)
+	if n < 3 {
+		return false
+	}
+	inside := false
+	for i, j := 0, n-1; i < n; j, i = i, i+1 {
+		pi, pj := g.Points[i], g.Points[j]
+		if (pi.Y > pt.Y) != (pj.Y > pt.Y) &&
+			pt.X < (pj.X-pi.X)*(pt.Y-pi.Y)/(pj.Y-pi.Y)+pi.X {
+			inside = !inside
+		}
+	}
+	return inside
+}
+
+func (g Polygon) Bounds() Rectangle {
+	if len(g.Points) == 0 {
+		return Rectangle{}
+	}
+	minX, maxX := g.Points[0].X, g.Points[0].X
+	minY, maxY := g.Points[0].Y, g.Points[0].Y
+	for _, p := range g.Points[1:] {
+		if p.X < minX {
+			minX = p.X
+		}
+		if p.X > maxX {
+			maxX = p.X
+		}
+		if p.Y < minY {
+			minY = p.Y
+		}
+		if p.Y > maxY {
+			maxY = p.Y
+		}
+	}
+	return Rectangle{X: minX, Y: minY, W: maxX - minX, H: maxY - minY}
+}