DOES ALPHABLENDING POSE A THREAT TO PERFORMANCE?
Not necessarily. I've had alphablending turned on, with 10+ different types of vegetation, with a total of about 40,000 vegetation objects present on the terrain and still no noticeable drop in performance.
It's all going to depend on your system, but I honestly do not believe that AlphaBlending is capable of as large of a performance drop as everyone thinks. Actually I would bet on it.
Plus, you have the option of leaving sprites on and determing at what distance the vegetation becomes a sprite. Sandbox gives you lots of freedom about how you want vegetation to render, and at what distance it does it.
IS ALPHABLENDING NEEDED AND DOES IT ACTUALLY MAKE VEGETATION LOOK BETTER?
Is Alphablending "needed"? There is no true answer to that question. That is up for you to decide because it is your map and your the creator. You decide what is needed.
Does Alphablending make your vegetation look better? There is a LARGE misconception about this matter and I have to say that those of you that say AlphaBlending should not be used, have not seen what AlphaBlending can and can not do.
I personally have performed several test's with AlphaBlending and documented those tests with screenshots. Although I can not post the screenshots because I do not have webspace to do so (unless someone wants to offer space for these small images), I can give you proof that AlphaBlending in many cases is required for "good looking" vegetation and in some cases it just comes down to preference.
After a lot of experience with using Sandbox I have a "preferred" way that I do things. Since we are on the subject of alphablending I am going to explain some of my technique for how I set vegetation.
When I get to the stage of mapping where I want to place vegetation and begin placing vegetation objects I place the first object of that type (shift+click) on the terrain, zoom in closely so that the entire object is fitted to the perspective window and start to set the properties for that object.
The first thing that I normally do is set Bending for 1. This is a setting you will have to experiment. Usually a good setting is somewhere in between .3 and 1.0. A setting of 1.0 is usually a very realistic "bending in the wind" effect for your trees, palms, and grass.
If this is a large object such as a tree I will usually side Hideable to True so that AI can hide behind this object.
Brightness, I won't touch until I Generate Surface Textures. Normally after Generating Surface Textures those veggies which start out too bright will get darker.
I've also been experimenting with CastShadows + RealTimeShadows. With 1000's of vegetation objects (mostly the trees, and bushes) set to CastShadows+RealTimeShadows (which are shadows that move in real time with your vegetation) there was also no significant performance drop. None at all that I could determine.
You will have to experiment on your own, but I like to set CastShadow for True and RealTimeShadow for True.
Next, I will switch AlphaBlending to TRUE and FALSE several times making a comparison from a few different distances. Whether AlphaBlending looks better always depends on the SPECIFIC vegetation object your using it on. Some look better with it and others look better without it. There are a few that you won't be able to tell a difference at all so it is better to just leave it set for False on those objects, so that your not using up those "precious resources" everyone talks about.
SpriteDistRation, ShadowDistRatio and MaxViewDistRatio are settings you will have to experiment with depending on what the rest of your settings are, your map, etc. If your using AlphaBlending, CastShadow and RealTimeShadows, then you obviously want to pick these settings wisely so that your vegetation isn't becoming a sprite at a very far distance. You want your object to become a sprite at a distance where you won't notice a difference of whether it is a sprite or not (usually 1 is fine, or even .7) for SpriteDistRatio. Your vegetation should become a sprite at the lowest possible distance without losing overall visual appeal. MaxViewDistRatio's setting for Trees needs to be set for a larger setting than that of grass. Obviously trees are large and realistically you would be able to see a tree for a MUCH longer distance than a few blades of grass.
UseSprites: Set this for Yes. If you don't like those ugly boxes that appear with sprites set on then you can click Tools, Reload Terrain. You don't have to Generate Surface Textures to get rid of these boxes. Reload Terrain will suffice and it is much quicker. You could also set SpriteDistRatio to a larger number, but it's not very logical to do so just because you dont want to see those boxes. They will go away once you Reload Terrain, Generate Surface Textures, etc and you won't see them in the game.
After getting the settings how I want them I begin setting objects down one by one (shift+click). I do this one by one, because usually I don't like to use distribute vegetation. Then each time I place a veggie I will CTRL+click+drag to scale the object. You may also use the Size and SizeVar settings if you want vegetation to be placed at random sizes.
That is all for now. :-)
Athlon XP 2600+
ATI Radeon 9700 Pro
[This message was edited by AcidOsmosis on Sun April 18 2004 at 11:10 PM.]
[This message was edited by AcidOsmosis on Mon April 19 2004 at 11:14 AM.]