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jPCT - a 3d engine for Java => Support => Topic started by: stormp on June 14, 2007, 11:24:20 am

Title: building custom plane: is there an addTriangle() order?
Post by: stormp on June 14, 2007, 11:24:20 am

Hi,

I was experimenting with building a custom plane.  Is there any order which the addTriangle() or the vectors must be added?

This works:

Code: [Select]

objSurface.addTriangle(new SimpleVector(-8.0f,  8.0f, 0.0f),
                       new SimpleVector( 8.0f,  8.0f, 0.0f),
                       new SimpleVector( 8.0f, -8.0f, 0.0f));

objSurface.addTriangle(new SimpleVector( 8.0f, -8.0f, 0.0f),
                       new SimpleVector(-8.0f, -8.0f, 0.0f),
                       new SimpleVector(-8.0f,  8.0f, 0.0f));

Where as this doesn't work:

Code: [Select]

       
objSurface.addTriangle(new SimpleVector(-8.0f, 8.0f, 0.0f),
                       new SimpleVector( 8.0f,  8.0f, 0.0f),
                       new SimpleVector( 8.0f, -8.0f, 0.0f));

objSurface.addTriangle(new SimpleVector(-8.0f,  8.0f, 0.0f),
                       new SimpleVector(-8.0f, -8.0f, 0.0f),
                       new SimpleVector( 8.0f, -8.0f, 0.0f));


Can someone explain? :)

Thanks.

Title: Re: building custom plane: is there an addTriangle() order?
Post by: EgonOlsen on June 14, 2007, 12:25:26 pm

Quote from: stormp on June 14, 2007, 11:24:20 am

Can someone explain? :)

The docs for addTriangle already do so:

Quote

The vertices have to be defined counter-clockwise because jPCT backface culls them by default.

Your second code works...it's just that the object will be visible from the other side.

Title: Re: building custom plane: is there an addTriangle() order?
Post by: stormp on June 14, 2007, 12:39:29 pm

Doh! I cant believe i didn't notice that.  thx.