Outrun style road demo MSX2

Comparison with SMS is irrelevant : its enhanced VDP had an additional mode, the mode 4, which gives it almost V9990 capacities. It's way more powerful than an MSX2.

It's impossible. There's too many factors (and therefore combinations) in order to precompute the tiles:
1) the start point of each segment's borders (8)
2) the different slope of each segment's borders (22)
3) the different width of each segment's road strips (16)
4) the change of slope between each segment (176x176=30976)
We're talking here about more than 87 millions possibilities.
Forget about precomputed tiles!

I think you guys do not understand my problem (or maybe I was not clear enough). To simplify things, let's say you have a screen made of 5x4=20 tiles, with an available tileset of 20 tiles also.

+--+--+--+--+--+
|  |  |  |  |  |
+--+--+--+--+--+
|  |  |  |  |  |
+--+--+--+--+--+
|  |  |  |  |  |
+--+--+--+--+--+
|  |  |  |  |  |
+--+--+--+--+--+

You know that, geometrically, the road will not be taking more than 12 tiles , which is OK, because it leaves 8 tiles for the road shoulder. But you do not know in advance where the tiles will be, because it's the rendering engine that will decide. And the only way to draw the road (in bitmap mode) is to fill the screen with the 20 consecutive tiles of the tileset, and let the rendering engine draw the road in the tiles.

+--+--+--+--+--+
| 0| 1| 2| 3| 4|
+--+--+--+--+--+
| 5| 6| 7| 8| 9|
+--+--+--+--+--+
|10|11|12|13|14|
+--+--+--+--+--+
|15|16|17|18|19|
+--+--+--+--+--+

But by doing so, you don't know which tiles are drawn, and which tiles are empty. Unless you track them and make a separate list, each time you draw some pixels in them. Let's say you have such a list. Then, the tiles which are NOT in that list will give you the tiles you can use to draw the road shoulders. Which means that the tiles to draw the road shoulder will be different for each frame, and that you will have to fill each one. Doable, but it will probably be sluggish.

At first, I was enthusiastic about SCREEN4 because I thought it gave an efficient approach: you fill the screen first with 4 tiles that will represent the road shoulders, and then you have only to draw those 4 tiles to make the full background for that road.

+--+--+--+--+--+
| 0| 0| 0| 0| 0|
+--+--+--+--+--+
| 1| 1| 1| 1| 1|
+--+--+--+--+--+
| 2| 2| 2| 2| 2|
+--+--+--+--+--+
| 3| 3| 3| 3| 3|
+--+--+--+--+--+

But by doing so, you then cannot draw the road tiles in bitmap mode, because you have already decided which tiles are going to be used, and now there's 4 tiles missing from the tileset! You need the full tileset available in order to draw in bitmap mode, because you never know where the road will be.

But you have to admit Atrag, that those blocky graphics are not as nice as his original setup...

Would it be sacrilege to state that, no matter how hard you try, the MSX1/2/+ simply wasn't made for Outrun games?

I can't recall having seen a g9k attempt though...

I agree. BTW the blocky pixels could be used for the road ony. The montains in the background could be in full resolution. The other elements (trees, other cars, signs ...) could be sprites.