Function triangleArea

common/collision.go:468–481

triangleArea computes the area of the triangle given by the three points

(p1, p2, p3 engo.Point)

// triangleArea computes the area of the triangle given by the three points
func triangleArea(p1, p2, p3 engo.Point) float32 {
	// Law of cosines states: (note a2 = math.Pow(a, 2))
	// a2 = b2 + c2 - 2bc*cos(alpha)
	// This ends in: alpha = arccos ((-a2 + b2 + c2)/(2bc))
	a := p1.PointDistance(p3)
	b := p1.PointDistance(p2)
	c := p2.PointDistance(p3)
	alpha := math.Acos((-math.Pow(a, 2) + math.Pow(b, 2) + math.Pow(c, 2)) / (2 * b * c))

	// Law of sines state: a / sin(alpha) = c / sin(gamma)
	height := (c / math.Sin(math.Pi/2)) * math.Sin(alpha)

	return (b * height) / 2
}

// CollisionComponent keeps track of the entity's collisions.
//