Making of LLemMings

A better builder

GPT-4: ChatGPT completely failed at this prompt, but GPT-4 nailed it

over and over.

A lot of bugs in the builder/digger code showed themselves once the game
was properly played. This code is a lot more robust and this same code will
also be used for digger.

>>> Prompt:
Using a filled rectangle-drawing algorithm, figure out the x/y
of the pixels affected when drawing a rectangle from in front of the lemmings feet
when given: angle (0-360), length and height (in pixels) of the rectangle. Regardless
of angle of the rectangle, it's length and height should remain the same.

The rectangle should end if the _entire_ height of it is obstructed, or the
rectangle would hit the border of the canvas (use canvas.height/width). You can
check for obstruction on canvas using an already existing function (you do not
need to reimplement this): isPixelOneOf(oldImgData, x, y, collisionColors). The
obstruction check should allow for some forgiveness as the terrain is not always
smooth. That is, at the very start of the rectangle (at lemming's feet)
we allow for obstructions of up to 4 pixels on the Y axis -- the rectangle should then
start above that obstruction. Note that the rectangle MUST "rest" on an obstruction
on the Y axis (the bottom-most pixel of it must have an obstruction under it).

The variable collisionColors should be passed into this new function.

The front of lemming can be determined by looking at lemming's velX (positive
value: moving right).

A lemming has these properties, its x/y position is the top-right of the lemming.
this.width = 10;
this.height = 20;
this.x = x;
this.y = y;
this.velX = 0;
this.velY = 0;

Note that a lemming's position might be a double, but when checking for collisions
and storing the x/y pairs, you would want them to be integers.

Declare function like this:
getRectanglePoints(lemming, angle, length, height, collisionColors)
The return value should be an array of x/y pairs of all pixels this rectangle affected,
that is, you don't actually draw anything.

It's important that the rectangle is entirely filled, there should be no pixel gaps

Only give me the new code, I don't need an explanation this time.