How to check the highest object's highest point on the y axis

Question

I'm still making the game about tower building using Unity and now I have problem that have haunted me for about week now.

Game mechanic for losing is that there is line which goes up at a certain speed and when it goes above the tower, game should end. I'm wondering is there any way of checking highest objects highest point(because of rotated objects and irregularly stacked objects)?

Answer 1

(Note. I might have some spelling mistakes in the naming of methods so proofread before copy-pasting) Since your are using a line, you might want to find the bounding box of an object. I have never tried the bounding box method so it might not work. The second method uses a little bit of math. If your line is vertical, then finding the highest point is easy. All you need to do is find the y position of the object and add half the y-scale to find the highest point. Note it will only work if the transform origin of the object is at the center. If the origin is at the bottom of the line you will have to add the full y-scale value. If its one third the way up, then only 2 thirds the y-scale value. I think you get the idea. This rule apples for the next condition too. If your line is at an angle, this is where it gets a little bit more complicated. We need to find the absolute value of the rotation in which the line is rotated at. Make sure the line is rotated at less than a 90 degree angle from being vertical. After this, we need to know the length of the line. Imagine a right triangle that the line itself is the hypotenuse, the base is the distance between the farthest left point of the line to the farthest right on the line(or other way around), and the distance from the lowest point of the line to the highest point of the line being the actual height of the triangle. Since we know the angle the line is rotated at and the length of the line, we need to figure out the ratio between the side opposite to the angle that represents the rotation the the hypotenuse(aka the length of the line) and the hypotenuse. This always stays the same if the rotation is the same for all right triangles. Because of this why use mathf.sin(), the rotation of the line. Remember to convert the rotation value(which is stored in degrees) to radians. This can be done by multiplying the rotation value by mathf.deg2rad. Once we know the sin, we multiply the length by the sin value that is outputted. Now we know how long the distance from the bottom to the top of the line is. Again, if the origin is the middle we add the y-position to half the value we get from the previous calculations. If it is in the bottom then the y-position plus the whole value we get from the previous calculations. Same rule as before. I am also quite new to Unity, only a little over a year of experience so there may be fallacies in my answer. Hope it helps. :)

Answer 2

There's a few ways to achieve this:

1) You can shoot a bunch of rays down from high up in the sky. Find all the hit.point positions and then loop through the points and store which building is the highest.

2) Another would be for each block of your building that is added - keep it as a child of an Empty Building gameObject. Then all you need to do is see which Building gameObject has the most children and you know it's the tallest. This assumes all blocks are the same size in Y and then you can easily calculate the height with highestChildCount * blockSizeY

3) Another way to do it would be to use the point in the line that is traveling up. Shoot a ray out of that point to the left and right. If it is hitting a building then the game continues. If it doesn't hit anything the game is over. This is the simpliest as it doesn't require calculation of any heights and your buildings can be made any way you like as long as they have colliders on it for the ray to hit. <--- This is likely the best method for what I'm hearing you asking.