f32/d3/rect.go
func RectWHD(x, y, z, w, h, d float32) Rectangle {
	return Rectangle{
		Min: Vec3{x, y, z},
		Max: Vec3{x + w, y + h, z + d},
	}
}
func RectWHD(x, y, z, w, h, d float32) Rectangle {
	return Rectangle{
		Min: Vec3{x, y, z},
		Max: Vec3{x + w, y + h, z + d},
	}
}
// RectWHD returns a rectangle whose origin is Vec3{x,y,z}, w and h are its
// width, height and depth.