objects have HP now, only direct hits hurt them

obstacle.go

@@ -8,6 +8,7 @@ import (
 
 type Obstacle struct {
 	Bounds v.Rect2d `json:"bounds"`
+	Hp     int      `json:"-"`
 }
 
 func (o Obstacle) distance_from_point(p v.Point2d) float32 {
@@ -48,6 +49,7 @@ func GenerateObstacles(count int, width, height float32) []Obstacle {
 					A: v.Point2d{X: x, Y: y},
 					B: v.Point2d{X: 20 + x + w, Y: 20 + y + h},
 				},
+				Hp: 10000,
 			})
 	}
 	return out

projectile.go

@@ -51,11 +51,15 @@ func (p *Projectile) Tick(g *game) {
 	arrived, _, pos := v.RectIntersection(r_dest, p.Position, travel)
 
 	if !arrived {
-		for _, obj := range g.obstacles {
+		for i, obj := range g.obstacles {
 			collision, _, pos := v.RectIntersection(obj.Bounds, p.Position, travel)
 			if collision {
 				arrived = true
 				p.Position = pos
+				obj.Hp -= p.Damage
+				if obj.Hp < 0 {
+					delete(g.obstacles, i)
+				}
 			}
 		}
 	} else {