The road turns not only left and right, like in the classic Pole Position, but also goes up and down. Other than the cars and the road, there are numerous objects both on and off the road.
Obviously, they made some kind of 2D track map, placing out all the road pieces and objects, and the background is just a static image which moves to the left and right (also slightly up and down). And the car you play as is of course going around on this 2D map as a position, checking collisions with other objects and all that usual stuff.
But how exactly does the game decide what to paint on the screen? Does the car "cast invisible rays" in all directions facing forward, and then draw the sprites and road pieces if they are "seen" currently, with the right scaling and x/y position on the screen, starting from the back and going forward toward the car so that objects in front are drawn the last?
Is that really how it was done? Because it sounds just like "raycasting" to me, a technique used by Wolfenstein 3D, which barely ran on the SNES even in a very crude form. As far as I know, Top Gear didn't use any special chip inside the cartridge, and there were also many other games which probably used the same technique for the SNES.
I've always wondered how this was done. The fact that it's an "illusion" rather than "real environments" (as would be the case with actual polygons) makes this and similar games very interesting to me to think about.
It seems to me that this would've been very difficult to code and get to run smoothly, but this game is very smooth and fast, and some levels even include what looks like "real 3D" tunnels sometimes. (But they may also be some kind of sprite-trick illusion.)
It's easy to say, as a non-programmer, that these old car games just "go on rails" and "give you a headache". Well, it may be kind of true, but they certainly don't just randomly put sprites on the screen; it's clearly calculated from some kind of rigid math/algorithm, based on a well-defined "world". I'm wondering how exactly they determined how to place the sprites on the screen so precisely and in such an optimized manner as to run this well on such a (relatively) weak console as the vanilla SNES.
If it used "invisible rays", how many (roughly) of those did it cast per frame? Are we talking 25 or 320 or even more?