Triangle check for valid vertices is incorrect

[DarthSharkie]

When fixing the line leak problem, I tested all the shapes that render themselves with multiple lines. Triangle and tetrahedron gave me problems, though, since they incorrectly flagged sets of vertices as invalid for their shapes.

For example, constructing the following triangle was disallowed:

        ParticleTriangle triangle = ParticleTriangle.builder()
                .vertex1(new Vector3f(2f))
                .vertex2(new Vector3f(3f))
                .vertex3(new Vector3f(1f, 4f, 6f))
                .amount(7)
                .particleEffect(ParticleTypes.END_ROD)
                .build();

These three points are not collinear, which is fairly easy to see: the first two points are multiples of the unit vector (1, 1, 1), while the third is not. However, the algorithm used detects them as not forming a valid triangle. The algorithm is this:

        float dotProduct1 = vertex3.dot(new Vector3f(vertex1).cross(vertex2));
        if (dotProduct1 == 0) {
            throw new IllegalArgumentException("Provided vertices do not produce a triangle");
        }

The operation performed there, if the vertices are named $a$, $b$, and $c$, with corresponding vectors of $\vec{A}$, $\vec{B}$, and $\vec{C}$, is the scalar triple product. If it evaluates to zero, then the three vectors are co-planar (this is checked in the tetrahedron, but using the fourth vertex, not the origin, as the starting point for each vector). Since $\vec{A}$ and $\vec{B}$ are clearly collinear, the three vectors must be co-planar.

The triangle check should only verify that $||\vec{AB} \times \vec{AC}|| \neq 0$. This proves two vectors are not collinear, which is all that is needed to prove a valid triangle.

[DarthSharkie]

I have a fix mostly ready, just adding a couple tests so it stays fixed.

[DarthSharkie]

Fixed in https://github.com/GitBrincie212/Apel-Mod/commit/6851e8dd40d259e36795968fbcf7ad9bc5701ce7