I tried to keep it concise, but a lot of text conglomerated nontheless. After all there's quite some time spent on systematic research into the issues adressed in this guide.
The terrain of every StarCraft map is composed from tiles and when it comes to it the properties of these tiles are what defines the structure of the map. And with the very first step of your map building process, picking a tileset for your map, you already decide which tile attributes and combinations of those will be available to you and which won't.
Some properties apply to whole tiles and others to the subtiles whereat every tile is composed of 16 (4x4) subtiles.
Examples for attributes that apply to the subtiles would be the terrain level (low, medium or high) and the walkability.
A Well known tile attribute that applies to whole tiles is buildability. It is important to mark that any tile that is fully or partially unwalkable is automatically unbuildable, even though SCMDraft does not display buildability correctly for some of those tiles (some doodad tiles in different tilesets).
However, there are at least 3 more attributes to tiles: cover provision, vision block and movement influence.
The last one refers to the effect that different tiles (most notably on bridges and ramps) have a certain influence on how units on them move that goes beyond the effects of walkability or terrain level (i.e. units may cross an unobstructed area of different fully walkable tiles on different paths or even try to avoid certain tiles while moving unusually smooth on others). I do not know how exactly the pathfinding algorithm of the StarCraft engine works or what exactly this hidden tile porperty does to influence movement, so that won't be what this guide is about...
What this guide is about are in fact the two other and less well known (or at east not well understood by most people) tile attributes mentioned above: cover providision and vision block.
I. Tiles that provide cover.
Example: Zerg uses the cover of a "force field" to assault a terran's choke in (4)Desertec (in case you are wondering about the obviously extremely retarded bunker placement - it was an AI game...). Note how multiple projectiles from the Hydralisks miss a Goliath on the protected area.
It is well known that certain doodads provide cover for units on them. The effect is basically the same as you can observe with units shooting up a cliff or (albeit much stronger) dark swarms - there is a 50% chance* for all ranged attacks on them to miss (this works by moving the impact point of the projectile, thus splash damage will still fully apply). Some people (wrongly) attribute this effect to the sprite of those doodads, and in deed all cover providing doodads in any tileset come with a sprite. But the cover effect itself is an attribute of the doodad tiles. Furthermore it seems to be true that if a certain doodad provides cover all tiles of that doodad are cover providing. If the central point of a unit's collision box is above one such tile the cover effect will apply to that unit.
*Blizzard officially mentions a 30% miss-chance. But actual statistic evaluation suggests a real miss chance of 50% both for units uphill and under cover. Both cover effects do not stack, i.e. a unit that is on higher terrain and under cover will still only have a 50% chance to be missed by ranged attacks. Like the miss chance associated with terrain level and unlike dark swarms the cover effect also applies to buildings. Implications of this are very limited though because all cover providing tiles are unanimously unbuildable.
To give you a general overview I have ordered all miss chances into a table:
even level cover***
up level cover
miss chance for units:
miss chance for buildings:
**up level means the attacking unit is on a lower terrain level than the target
***cover describes the cover effect provided by tiles furtehr explained in this guide
Unlike the very similar effect of terrain level (which also inadvertedly brings a one sided vision advantage with it) this effect hasn't been used in maps a lot. The reason is simple: Since those tiles belong to doodads that also happen to obstruct unit movement mappers keep that stuff away from their battlefields for the most parts and if they don't they annoy players at best and cause severe bugs at worst (maybe you remember the former pro-map (3)Demon's Forest that used forests of tree dodads to create areas of cover and vision obstruction - and was quickly removed from all map pools because the dense pattern of trees caused some severe unit collision bugs with certain units).
However the problems with obstructed movement can obviously be solved if you use tile editing and only select fully walkable tiles for the areas that you want to have the cover providing effect on.
There are four tilesets that contain cover providing doodads: Jungle (all tree doodads), Badlands (all tree doodads), Ice (big building doodads) and Desert ("hut" doodads).
Luckily three of these, Jungle, Ice and Desert, provide one with these much desired tiles. Because a picture can tell more than a thousand words at times, here's a complete list of all tiles one can use for this purpose that will help you find those tiles in your indexed tile palette. The numbers are the tile indices (strangely enough the maximum tile index differs in different tilesets).
Please pay attention to this, if not for the purpose of actually using the listed tiles to achieve the desired effect then at least for the sake of avoiding those tiles for any other purpose (like making ramps unbuildable) because you'll end up with a severely bugged map. There have been countless examples for this in the past, including the former ICCup version of (2)Spinel Valley. Learn from other people's mistakes, don't make them all yourself.
The desert tileset is probably the best suited if you want to create a map using the effect because it provides you with the widest variety of usable tiles, terrain types and textures. And all the tiles generate very smooth unit pathing.
Terrain: Dirt (low terrain level)
Terrain: High dirt (medium terrain level)
The tiles marked in magenta are tiles that I'd recommend you to use. In this case those they contain some interesting and distinctive textures (pieces of debris).
1104.00 and 1104.03. are the tiles I used in (4)Desertec.
Terrain: Sand dunes (low terrain level)
Due to its textures sand dunes terrain tends to become blocky if you try to fit unmatching tiles together. The 1078s tiles are particularly useful to avoid this effect. Also mark that the 1082s tiles marked in green do not provide cover. They are nontheless extremely useful tiles if you want to create unbuildable sand (p.e. for ramps). All this analoguely applies to the high sand dunes tiles below.
Terrain: High sand dunes (medium terrain level)
Ice terrain only provides you with blinding snow tiles for the purpose. Players may hate you for it, use at your own risk.
Terrain: Snow (low terrain level)
Terrain: High snow (medium terrain level)
Yes, there's only that one tile. Sucks, eh?
Besides the tiles listed here the dirt tree doodads also provide cover, but they don't come with fully walkable tiles. So you are limited to jungle terrain types in this tileset. Contrary to the other tileset jungle terrain is rather user friendly because the terrain textures allow you to basically put together these tiles in any oder you like without genrating blockyness.
Terrain: Jungle (low terrain level)
Terrain: High jungle (medium terrain level)
II. Tiles that block vision.
Example: Hydralisks breaking through a vision barrier to ambush some Dragoons on (4)Pyrolysis.
Many doodads obstruct the vision of ground units. But normally the effect of single scattered doodads is so little that it hardly ever matters. Large conglomerates of vision blocking doodads can work like a cliff (for example the ovi spots at the nats in (3)Hazard Black)
It's worth noting that the vision block is absolute, meaning that all ground units are affected, even when they are on a higher terrain level than the vision barrier. Air units are not effected.
The problems with vision blocking tiles are essentially the same as with the aforementioned cover providing tiles - they come with doodads that also obstruct unit movement which drastically limits their usefulness. To make things worse contrary to what I said about the cover effect, that a doodad blocks vision does not imply that all its tiles do so too.
In effect although all tilesets contain some sort of vision blocking doodads there are only two tilesets which contain tiles that exhibit both the desired properties of being 1.fully walkable and 2. vision blocking: Ash and Ice.
Ice terrain of course is special in a) that it provides both cover providing and vision blocking tiles and b) you probably should think twice about using it nontheless... Bad conincidence, life isn't fair I guess...
On the other hand at least you get something rather optically pleasing because the vision blocker for ice terrain is actually a whole certain stone doodad:
Terrain: Dirt (low terrain level)
Terrain: High dirt (medium terrain level)
This one's particularly easy to find because it's just at the bottom end of the indexed ice terrain palette.
Here's your number one reason to create more Ash maps. Admittedly those tiles are frickin' ugly though, so you may consider blending them with some sprites or something as I did on (4)Pyrolysis. You can cover whole areas with these tiles of course, but tests that I ran on it suggest that it may not exactly provide the most friendly unit behaviour :(...
If you only want to create thin barriers like in (4)Pyrolysis remember to always have the tiles touch each other at one edge, only having them touch on the corners won't provide a full vision block (this is also true for vision blocked by higher terrain by the way).
Terrain: Dirt (low terrain level)
Terrain: High dirt (medium terrain level)
The basic things displayed in this guide are known for a long time but have been used in few maps nontheless. Here are some examples from the BWMN database.
As far it was this map, by korean mapper Sinsago, that first used the vision block effect here on site. He did not introduce or explain the effect at all, so the map received a grant total of three posts and the effect no attention at all.
Much later he used the effect again on his map "Ready to Fight", and this time he provided a screenshot displaying the effect, making it more widely known on site, but still few mappers ever used it for their own maps. I susupect that that is because of the general unpopularity of ice terrain. This map itself is little spectacular despite the (too) extensive use of vision blockers.
A former short-lived korean league map that used tightly placed badlands tree doodads to create areas of both vision reduction and cover. This created problems of which the incredibly annoying pathing for even small groups of units was definitely the lesser one. The very reason why this map was short-lived was that units got imoveably stuck on the tree doodas as result of unit stack effects. For there are lots of effects in StarCraft that create a unit stack, such like Archons morphing, Vultures laying mines, Zerg units burrowing on top of each other and workers moving to resource fields, this was a serious and commonly occuring problem.
Vultures getting stuck on tree stumps after laying mines on Demon's Forest
Conclusion: This has been thoroughly tried and is definitely not the way to go.
Attempted bugfix of Demon's Forest by ProTosS4EveR. He used the stone doodads on ice terrain to create the vision blocking effect. He also attempted to replicate the cover effect of the tree doodads by using a checkerboard pattern of medium and low ground tiles as he explained in the following picture:
But this doesn't really work out so well, if you think about it. First of a checkerboard pattern of high and low tiles means that statistically only 50% of all ranged units on it have a 50% chance to miss the other 50% of units on it. In total you come out at a mere 12.5% miss chance.
On top of that the medium ground tiles in the pattern cause vision bugs by allowing units to look over nearby cliffs as shown below:
Conclusion: Not worth all the fuzz, better stick to one effect, cover or vision block, don't try to combine them, it doesn't work out that well.
This map also uses stone doodads to limit unit vision in vast areas of the map, most of it for some reason though on a giant center island that takes up about a quarter of the available map space and whose only somewhat useful feature seems to be that it tanks the 3rd gas expansions...
He obviously copied the pattern from Demon's Shiver, meaning he has got the same vision bugs. It does probably not really matter though for this map has so many (intended) imbalances that you would not play it seriously anyway.
Some time ago I started to systematically employ and fathom different implementations of both effects on my maps. Here's a full list of maps I used one of them on.
It might not be apparent with a brief look, but I put cover providing (tree doodad) tiles under all the assimilator gates to make them harder to destroy. If you want to create a cover protected neutral building in one of your maps it is actually enough to put a cover providing tile right under the center of it.
Inspired by the vision blocking grass and smoke in SC2 I created Pyrolysis in which I made extensive use of vision blocking tiles to create narrow vision barriers on multiple strategic spots on the whole map, including under jumpable mineral formations. For a complete overview I highlighted all the barriers in red in the above picture. To achieve a somewhat similar effect to the grass in Sc2 and to cover up the blocky uglyness of the bare vision blockers I used two bleak tree doodads from ice tileset. Unaware of the actual effect some people where complaining about "the useless and ugly stuff" at first ;P
I used the same vision barriers as in Pyrolysis under the formations of the mains, jumpable minonlies and the jumpable stacked mineral expos in the upper part of the map as well as unde the "elephant".
This map makes use of both cover providing and vision blocking tiles. I used pylon field sprites to distinguish the cover protected areas as "force fields" and vision blockers under the egg walls at the main backdoors.
My new map featuring the "force field" theme with wide cover protected areas under pylon fields.
That's it so far. I may add in a section about different uses of the effects in maps or balance aspects, but ideally some actual game experience can be collected and more map using the effects created first.
I didn't read it yet, but it's a lot x_x
Where did you learn all this stuff xd?
I want to take the same course lol
Arctimes its really good :D its worth it.
Is your name white?
The parts adressed in this guide I figured out all on myself.
It's not nearly as much work as you might think though, you can test a whole tileset pretty quickly (in about 15 minutes or so) if you start with a good preselection of tiles.
Freakling started making Starcraft maps before Starcraft came out :D
lol, no, my name is not white, look at jungle's.
And maybe you can test a whole tileset really fast, but that's a lot of imformation xD
Update with more info.
Good stuff. I wish we had more active mappers so we could share this knowledge with.
modified by CrystalDrag
I wrote this for you to read it... Of course it DID NOT. Because: IT IS A COVER PROVIDING TILE, NOT A VISION BLOCKING TILE.