# Detecting if a tri is inside an axis-aligned cube

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how i do that? some approach to that is using ray-tracing collision and classifying the tri vertices about their side of cube planes, but i'm wondering if there is a faster way....

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you said axis-aligned so basically you're just checking against the box's min and max values along the axial directions.

bool isTriInside(Vertex *vertices){    for (int i = 0; i < 3; ++i )    {        if ( vertices.x < box.minX || vertices.x > box.maxX            || vertices.y < box.minY || vertices.y > box.maxY            || vertices.z < box.minZ || vertices.z > box.maxZ )        {            //this vertex is outside the box            return false;        }    }    return true;}

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the seperating planes algorithm is what you need.

google is better at explaining than me.

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Quote:
 Original post by Palidineyou said axis-aligned so basically you're just checking against the box's min and max values along the axial directions.*** Source Snippet Removed ***

quite incorrect.

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Quote:
 Original post by Eelcoquite incorrect.

no, it's correct. he said "axis-aligned", not Object Oriented BOunding Box, in which case you have to check against the planes. with axis aligned you just have to check the coords.

-me

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Palidine, your algorithm just check if the vertices is inside the cube
a poly could overlap a cube with all it's vertices outside the cube

Eelco, is "seperating planes algorithm" the fastest way for this case?

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Quote:
 Original post by Jungle BoyPalidine, your algorithm just check if the vertices is in the cubea poly could overlap an cube with all it's vertices outside the cubeEelco, is "seperating planes algorithm" the fastest way for this case?thx for your replies

Ah, you said inside, which i took to mean "contained by", not "intersecting".

-me

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sorry for the "axis-oriented", the correct is "axis-aligned"
just edited the title....

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Quote:
 Palidine, your algorithm just check if the vertices is inside the cubea poly could overlap a cube with all it's vertices outside the cube.
I take it from this that you don't want a 'tri in axis-aligned cube' test, but rather a 'tri intersects axis-aligned cube' test. In that case eelco's suggestion may be your best bet.

What's the test for? Is it a pre-processing step, e.g. octree construction? Or something else? Depending on the context, different solutions may be more or less appropriate. It's hard to say though without knowing more about the application.

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sorry again, it should be "tri intersects or inside an axis-aligned cube"
just a poor english issue

i need to know which tris are intersecting/inside octree's cubes

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