Modelling: Number of vertexes and performance

[ScionTheWorm]

Hi I wondered if anybody had experience or knowledge about how the number of vertexes in 3d models (units) affect the performance in battle. For instance, if you give an existing model from vanilla rome a robe and maybe another item, the number of vertexes will be between 400 and 500. CA made 4 versions of every model from different distances; 100, 200, 300, 400 vertexes. Is this highly neccessary, and more important: will a unit with a number of vertexes that tends to 500 slow down the game?

[Bwian]

3D meshes are usually judged by 'polygons' rather than vertices.

Polygons are the actual triangles that make up the visible surface of the mesh. Vertices are 'corners' and not a good guide for a models complexity.

Put simply, the more polygons a unit has, the more CPU of Gfx card effort it takes to move and redraw it. To get a smooth display, you need to render around 30 frames per second... so EVERY polygon on screen has to be drawn 30 times a second.

So...if you have a model made up of 1000 polygons, thats 30,000 polygons every second to render your model. Now....thats for one model...your unit could have 240 models in it. There could also be 20 units on screen....do the math...thats a LOT of polygons. Then add the ground, trees, buildings etc.

So, to get back to your original question....if you added an extra 100 polys to make your cloak. Thats 3,000 polys a second to draw for each of your 240 units. Thats arond 750,000 polygons for every unit on screen. So...yes it will slow down the game Depending on the power of your CPU and Gfx card, the slowdown may be minimal. If, though, you are pushing your computers limits, this could well tip things over the edge and result in seriously jerky displays and lots of slow-downs.

Now...this leads us on nicely to the second question. CA made 4 levels of detail for their models. This is common industry practice, and does have a MASSIVE impact on your game.

Lets look at it with some numbers If your highest detail model has 1000 polygons, a nicely detailed face and so on, it looks good close up but takes a lot of resource to draw. Pull back a ways, and you CANNOT SEE THE DETAIL. So...why waste CPU cycles displaying it. The game does it by switching to a less detailed model. Each level of detail has progressively less detail, and requires fewer resource to draw it. Since, in practice, most of your units WON'T be right in the foreground, this saves a lot of bother and makes the game playable with as many units on screen as it has.

ANY mod-maker should follow that pattern and take the trouble to add the low detail models too. If you don;t you can easily end up with a mod that can only be played on a high-spec machine or with minimal units sizes.

Thats pretty much it really

[ScionTheWorm]

Thank you so very very much! That could not been a better answer! Will certainly take the time making those four models, when you put the numbers out like that the difference in performance has to be huge

(Vertices not vertexes *practicing*)

[Bwian]

:D Glad to be of help