1) If you want different height levels, I would highly recommend using a polygon based map (essentially a surface plot), taking advantage of 3D HW if present.

2) If you use a Z-buffer when rendering the map, the screen->world mapping should be straight forward, since you have full (x,y,z) data available. Without the Z-buffer, you'll need another way to fill in the missing value. (Without multiple heights, this is not an issue since you know that Z=0). Normally, however, you can make various tradeoffs but that depends heavily on the way you store and render the map.

/Niels

Do you mean tiles or true 3D?

For tiles, if the terrain is exactly like SC2000 where the slopes are rather steep, your idea would probably work. Where tiles are like the ones in Industry Giant, Enemy Nations, and Seven Kingoms II, purging the list would be wasteful. The map does not jump from one elevation to another that quickly so therefore it would be just fine to render just a few extra tiles beyond the viewpoint.

[This message has been edited by Ðragun (edited November 15, 1999).]

I know some extensive 3D (a software accl. DOOM\Quake wannabe) but have a seriously hard time trying to render something like SimCity 2000 in 3D. Yes, I was talking about tiles.

I got two questions:

1)
How can you blit isometric tiles like SimCity 2000 (with all the slopes and elevation) correctly and efficently? I've thought of purging the map that I "think" would be visable and sort each tile by x, y, and z coords. Not sure if that's efficient or not though.

2)
How can I get the mouse to interact with the map correctly when there are slopes and elevation? I know how to do it with flat isometric maps with mousemaps but I dont think that will work with heighted isos.

There is no reason why the ground level cannot be layed out as texture mapped polygons. I'm sure your artist will find it a lot easier to do 2D textures than various odd shaped slopes and planes.

This is an ever occuring problem: When people talk iso they immediately think funny shaped tiles. ISO is a type of 3D to 2D projection that offers a specifc game atmosphere and a great overview for strategy type games. Since it does not have perspective distortion it happens to be good for tiles (and sprites in general), but how you render it is completely irrelevant.

/Niels