// Copyright NVIDIA Corporation 2008 -- Ignacio Castano <icastano@nvidia.com>

#include "nvmesh.h" // pch

#include "SingleFaceMap.h"

#include "nvmesh/halfedge/Mesh.h"
#include "nvmesh/halfedge/Vertex.h"
#include "nvmesh/halfedge/Face.h"

#include "nvmath/Vector.inl"

using namespace nv;



void nv::computeSingleFaceMap(HalfEdge::Mesh * mesh)
{
    nvDebugCheck(mesh != NULL);
    nvDebugCheck(mesh->faceCount() == 1);

    HalfEdge::Face * face = mesh->faceAt(0);
    nvCheck(face != NULL);

    Vector3 p0 = face->edge->from()->pos;
    Vector3 p1 = face->edge->to()->pos;

    Vector3 X = normalizeSafe(p1 - p0, Vector3(0.0f), 0.0f);
    Vector3 Z = face->normal();
    Vector3 Y = normalizeSafe(cross(Z, X), Vector3(0.0f), 0.0f);

    uint i = 0;
    for (HalfEdge::Face::EdgeIterator it(face->edges()); !it.isDone(); it.advance(), i++)
    {
        HalfEdge::Vertex * vertex = it.vertex();
        nvCheck(vertex != NULL);

        if (i == 0)
        {
            vertex->tex = Vector2(0);
        }
        else
        {
            Vector3 pn = vertex->pos;

            float xn = dot((pn - p0), X);
            float yn = dot((pn - p0), Y);

            vertex->tex = Vector2(xn, yn);
        }
    }
}