Method ComputeCylinderMapping

code/PostProcessing/ComputeUVMappingProcess.cpp:214–282

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// ------------------------------------------------------------------------------------------------
void ComputeUVMappingProcess::ComputeCylinderMapping(aiMesh *mesh, const aiVector3D &axis, aiVector3D *out) {
    aiVector3D center, min, max;

    // If the axis is one of x,y,z run a faster code path. It's worth the extra effort ...
    // currently the mapping axis will always be one of x,y,z, except if the
    // PretransformVertices step is used (it transforms the meshes into worldspace,
    // thus changing the mapping axis)
    if (axis * base_axis_x >= angle_epsilon) {
        FindMeshCenter(mesh, center, min, max);
        const ai_real diff = max.x - min.x;

        // If the main axis is 'z', the z coordinate of a point 'p' is mapped
        // directly to the texture V axis. The other axis is derived from
        // the angle between ( p.x - c.x, p.y - c.y ) and (1,0), where
        // 'c' is the center point of the mesh.
        for (unsigned int pnt = 0; pnt < mesh->mNumVertices; ++pnt) {
            const aiVector3D &pos = mesh->mVertices[pnt];
            aiVector3D &uv = out[pnt];

            uv.y = (pos.x - min.x) / diff;
            uv.x = (std::atan2(pos.z - center.z, pos.y - center.y) + (ai_real)AI_MATH_PI) / (ai_real)AI_MATH_TWO_PI;
        }
    } else if (axis * base_axis_y >= angle_epsilon) {
        FindMeshCenter(mesh, center, min, max);
        const ai_real diff = max.y - min.y;

        // just the same ...
        for (unsigned int pnt = 0; pnt < mesh->mNumVertices; ++pnt) {
            const aiVector3D &pos = mesh->mVertices[pnt];
            aiVector3D &uv = out[pnt];

            uv.y = (pos.y - min.y) / diff;
            uv.x = (std::atan2(pos.x - center.x, pos.z - center.z) + (ai_real)AI_MATH_PI) / (ai_real)AI_MATH_TWO_PI;
        }
    } else if (axis * base_axis_z >= angle_epsilon) {
        FindMeshCenter(mesh, center, min, max);
        const ai_real diff = max.z - min.z;

        // just the same ...
        for (unsigned int pnt = 0; pnt < mesh->mNumVertices; ++pnt) {
            const aiVector3D &pos = mesh->mVertices[pnt];
            aiVector3D &uv = out[pnt];

            uv.y = (pos.z - min.z) / diff;
            uv.x = (std::atan2(pos.y - center.y, pos.x - center.x) + (ai_real)AI_MATH_PI) / (ai_real)AI_MATH_TWO_PI;
        }
    }
    // slower code path in case the mapping axis is not one of the coordinate system axes
    else {
        aiMatrix4x4 mTrafo;
        aiMatrix4x4::FromToMatrix(axis, base_axis_y, mTrafo);
        FindMeshCenterTransformed(mesh, center, min, max, mTrafo);
        const ai_real diff = max.y - min.y;

        // again the same, except we're applying a transformation now
        for (unsigned int pnt = 0; pnt < mesh->mNumVertices; ++pnt) {
            const aiVector3D pos = mTrafo * mesh->mVertices[pnt];
            aiVector3D &uv = out[pnt];