C++ (Cpp) MeshObject::get_tex_coords_count Beispiele

Beispiel #1

void compute_smooth_vertex_tangents_base_pose(MeshObject& object)
{
    assert(object.get_vertex_tangent_count() == 0);
    assert(object.get_tex_coords_count() > 0);

    const size_t vertex_count = object.get_vertex_count();
    const size_t triangle_count = object.get_triangle_count();

    vector<GVector3> tangents(vertex_count, GVector3(0.0));

    for (size_t i = 0; i < triangle_count; ++i)
    {
        const Triangle& triangle = object.get_triangle(i);

        if (!triangle.has_vertex_attributes())
            continue;

        const GVector2 v0_uv = object.get_tex_coords(triangle.m_a0);
        const GVector2 v1_uv = object.get_tex_coords(triangle.m_a1);
        const GVector2 v2_uv = object.get_tex_coords(triangle.m_a2);

        //
        // Reference:
        //
        //   Physically Based Rendering, first edition, pp. 128-129
        //

        const GScalar du0 = v0_uv[0] - v2_uv[0];
        const GScalar dv0 = v0_uv[1] - v2_uv[1];
        const GScalar du1 = v1_uv[0] - v2_uv[0];
        const GScalar dv1 = v1_uv[1] - v2_uv[1];
        const GScalar det = du0 * dv1 - dv0 * du1;

        if (det == GScalar(0.0))
            continue;

        const GVector3& v2 = object.get_vertex(triangle.m_v2);
        const GVector3 dp0 = object.get_vertex(triangle.m_v0) - v2;
        const GVector3 dp1 = object.get_vertex(triangle.m_v1) - v2;
        const GVector3 tangent = normalize(dv1 * dp0 - dv0 * dp1);

        tangents[triangle.m_v0] += tangent;
        tangents[triangle.m_v1] += tangent;
        tangents[triangle.m_v2] += tangent;
    }

    object.reserve_vertex_tangents(vertex_count);

    for (size_t i = 0; i < vertex_count; ++i)
        object.push_vertex_tangent(safe_normalize(tangents[i]));
}