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Best Method to Apply Tyre Trails

Started by ErnieDingo Sep 10, 2016 at 11:29 AM 1 replies 1.7k views

Original Post

Sep 10, 2016 at 11:29 AM

Hi,

Just wanting to know if my application of this is correct. I want to add tyre tracks onto my sandy tracks to make it look like they are used.

I'm thinking of the following:

1. Build function to place a set of points in my editor.

2. Points are joined with bezier curves which are the skeleton for the road trail

3. The trail is then built up of a number of triangles that create a strip. The trail follows closely the lay of the land.

4. Strip has an normal mapped texture.

When I render the triangles.

1. turn of Z buffer write

2. render the normal mapped texture.

3. blend the colour darker/lighter depending on the normal.

Now, i'm thinking a normal might be over kill and I should just use an alpha map or even just a texture with grey lines on it?

is this the correct technique I should apply. Because I am looking at this overhead (and will all the time), it doesn't have to pass the success test at close range. It should be also flexible enough I can overwrite a once at most to make divergent trails.

Thoughts guys?

Degi

Sep 27, 2016 at 8:17 PM

HI,

Don't know if I understand correctly the problem. Isn.t it a trade off betwen quality and speed ? I think you probably have already faced many other.

I personally haven't ever done tyre trails but I suppose I would start with the normal mapped version, even with a temporary map, just to see how much it impacts the frame rate.

I think you will need alpha blend to mix two overlaping tracks, the upper tracks being opaque/overriding the lower one only where the second car has 'remodeled' the sand shape passing on it and fading at the border of such parts to avoid abrupt changes in the normal direction and color.

Also you will need to render the tracks in the order in which the cars generated them.

If you have far cry 3, you can take a look at its map editor (it comes with the game). It has a nice track-editing utility and you can inspect the result closely/experiment to get some inspiration.

ErnieDingo

Sep 27, 2016 at 8:55 PM

HI,

Don't know if I understand correctly the problem. Isn.t it a trade off betwen quality and speed ? I think you probably have already faced many other.
I personally haven't ever done tyre trails but I suppose I would start with the normal mapped version, even with a temporary map, just to see how much it impacts the frame rate.
I think you will need alpha blend to mix two overlaping tracks, the upper tracks being opaque/overriding the lower one only where the second car has 'remodeled' the sand shape passing on it and fading at the border of such parts to avoid abrupt changes in the normal direction and color.
Also you will need to render the tracks in the order in which the cars generated them.
If you have far cry 3, you can take a look at its map editor (it comes with the game). It has a nice track-editing utility and you can inspect the result closely/experiment to get some inspiration.

Pretty much my first thought are to do this. Thankfully the tyre tracks are static and effectively decals. But rather than use a stock decal type method i would like to build something a bit smarter which i will even use in my future car game.

Even though the terrain is a little rough. Im looking at the whole thing from a distance so o probably want something cheap that passes the glance test.

Graphics is taking most my time unfortunately and i just want to build some game play so don't want to have the prefect solution. Probably do the track layout with splines for the skeleton.

Video of current engine on my web site. Still early days but you will see basically what I'm going to attempt

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