Method updateTransform

core/2d/Sprite.cpp:985–1063

// MARK: visit, draw, transform

void Sprite::updateTransform()
{
    AXASSERT(_renderMode == RenderMode::QUAD_BATCHNODE,
             "updateTransform is only valid when Sprite is being rendered using an SpriteBatchNode");

    // recalculate matrix only if it is dirty
    if (isDirty())
    {
        // If it is not visible, or one of its ancestors is not visible, then do nothing:
        if (!_visible || (_parent && _parent != _batchNode && static_cast<Sprite*>(_parent)->_shouldBeHidden))
        {
            _quad.br.vertices.setZero();
            _quad.tl.vertices.setZero();
            _quad.tr.vertices.setZero();
            _quad.bl.vertices.setZero();
            _shouldBeHidden = true;
        }
        else
        {
            _shouldBeHidden = false;

            if (!_parent || _parent == _batchNode)
                _transformToBatch = getNodeToParentTransform();
            else
            {
                AXASSERT(dynamic_cast<Sprite*>(_parent), "Logic error in Sprite. Parent must be a Sprite");
                const Mat4& nodeToParent = getNodeToParentTransform();
                Mat4& parentTransform    = static_cast<Sprite*>(_parent)->_transformToBatch;
                _transformToBatch        = parentTransform * nodeToParent;
            }

            //
            // calculate the Quad based on the Affine Matrix
            //

            Vec2& size = _rect.size;

            float x1 = _offsetPosition.x;
            float y1 = _offsetPosition.y;

            float x2 = x1 + size.width;
            float y2 = y1 + size.height;

            float x = _transformToBatch.m[12];
            float y = _transformToBatch.m[13];

            float cr  = _transformToBatch.m[0];
            float sr  = _transformToBatch.m[1];
            float cr2 = _transformToBatch.m[5];
            float sr2 = -_transformToBatch.m[4];
            float ax  = x1 * cr - y1 * sr2 + x;
            float ay  = x1 * sr + y1 * cr2 + y;

            float bx = x2 * cr - y1 * sr2 + x;
            float by = x2 * sr + y1 * cr2 + y;

            float cx = x2 * cr - y2 * sr2 + x;
            float cy = x2 * sr + y2 * cr2 + y;