Given a Mesh instance, I’m looking to inspect 2 adjacent triangular polygons and determine the angle they intersect/are adjacent at.

Once I know the indexes of the 2 triangles that I want to run this analysis on, I think I can get their Vector3f data like so (but please correct me if I’m wrong!):

// Get indices of two triangles. They will be adjacent/touching each other.
int t1Index = getSomehow("t1");
int t2Index = getSomehow("t2");
Vector3f t1v1, t1v2, t1v3, t2v1, t2v2, t2v2;
t1v1 = new Vector3f();
t1v2 = new Vector3f();
t1v3 = new Vector3f();
t2v1 = new Vector3f();
t2v2 = new Vector3f();
t2v3 = new Vector3f();
Mesh mesh = getMesh(); // Get it somehow
// Populate t1 and t2's vector data.
mesh.getTriangle(t1Index, t1v1, t1v2, t1v3);
mesh.getTriangle(t2Index, t2v1, t2v2, t2v3);
// Calculate the angle at which they intersect (touch each other at).
// TODO: ???

Are there any “utils” classes/methods that might help me with this calculation? Or any known formulas that I could just implement myself? Thanks!

Hi @pspeed - in my simple game, users can inspect a mesh/model, select any two touching polygons, and I want to display the angle at which they intersect at. This might seem strange but is a very important aspect of the game!

For instance, take these two adjacent/touching triangles:

In this case, t1 = (A,B,D) and t2 = (A,C,D).

Perhaps these two triangles touch each other at a 0° angle, in which case they would form a plane with each other. Or perhaps they touch at 45°, or 90°, etc.

I need to calculate this angle (at which they touch each other).

Will your suggestion to calculate the dot product between them accomplish this? Thanks!