Function RemoveUVSeams

code/PostProcessing/ComputeUVMappingProcess.cpp:79–149

------------------------------------------------------------------------------------------------ Try to remove UV seams

// ------------------------------------------------------------------------------------------------
// Try to remove UV seams
void RemoveUVSeams(aiMesh *mesh, aiVector3D *out) {
    // TODO: just a very rough algorithm. I think it could be done
    // much easier, but I don't know how and am currently too tired to
    // to think about a better solution.

    const static ai_real LOWER_LIMIT = ai_real(0.1);
    const static ai_real UPPER_LIMIT = ai_real(0.9);

    const static ai_real LOWER_EPSILON = ai_real(10e-3);
    const static ai_real UPPER_EPSILON = ai_real(1.0 - 10e-3);

    for (unsigned int fidx = 0; fidx < mesh->mNumFaces; ++fidx) {
        const aiFace &face = mesh->mFaces[fidx];
        if (face.mNumIndices < 3) {
            continue; // triangles and polygons only, please
        }

        unsigned int smallV = face.mNumIndices, large = smallV;
        bool zero = false, one = false, round_to_zero = false;

        // Check whether this face lies on a UV seam. We can just guess,
        // but the assumption that a face with at least one very small
        // on the one side and one very large U coord on the other side
        // lies on a UV seam should work for most cases.
        for (unsigned int n = 0; n < face.mNumIndices; ++n) {
            if (out[face.mIndices[n]].x < LOWER_LIMIT) {
                smallV = n;

                // If we have a U value very close to 0 we can't
                // round the others to 0, too.
                if (out[face.mIndices[n]].x <= LOWER_EPSILON)
                    zero = true;
                else
                    round_to_zero = true;
            }
            if (out[face.mIndices[n]].x > UPPER_LIMIT) {
                large = n;

                // If we have a U value very close to 1 we can't
                // round the others to 1, too.
                if (out[face.mIndices[n]].x >= UPPER_EPSILON)
                    one = true;
            }
        }
        if (smallV != face.mNumIndices && large != face.mNumIndices) {
            for (unsigned int n = 0; n < face.mNumIndices; ++n) {
                // If the u value is over the upper limit and no other u
                // value of that face is 0, round it to 0
                if (out[face.mIndices[n]].x > UPPER_LIMIT && !zero)
                    out[face.mIndices[n]].x = 0.0;

                // If the u value is below the lower limit and no other u
                // value of that face is 1, round it to 1
                else if (out[face.mIndices[n]].x < LOWER_LIMIT && !one)
                    out[face.mIndices[n]].x = 1.0;

                // The face contains both 0 and 1 as UV coords. This can occur
                // for faces which have an edge that lies directly on the seam.