Translading camera with mouse after rotating with libGDX

Question

I'm building a map viewer and implemented rotating, panning and zooming with mouse just fine. The problem is when I try to pan after rotating the camera. If the user makes a vertical movement with mouse after the camera is rotated 30º, the camera will translade in that direction and not vertically.

This seems like it should have a simple solution, but I can't find anything. I can only think of recalculating the deltaX and deltaY according to the rotation angle, but this requires a lot of conditions depending on the quadrant I'll be on.

I did see this post with a very similar question, but I can't understand the answear.

Here's my code for panning:

public void pan (float startX, float startY, int screenX, int screenY) {
    float deltaX = (- screenX + startX) * this.zoom;
    float deltaY = (- startY + screenY) * this.zoom;
    this.translate(deltaX, deltaY);

    //Pan limits
    this.position.x = MathUtils.clamp(this.position.x, (float) (map.getMinX()-200),(float) (map.getMaxX()+200));
    this.position.y = MathUtils.clamp(this.position.y, (float) (map.getMinY()-200),(float) (map.getMaxY()+200));
}   

Is there something I'm missing? Thanks!

---

FOUND A SOLUTION:

I'll share my solution in case someone else comes looking for it. My math is not in great shape and I think this could be a lot more elegant. If someone comes up with a simpler aproach please let me know.

Basically, I take my deltaX and deltaY and recalculate them acoording to the new rotated axis.

When i apply my rotation, I calculate the angle of rotation from 0º to 360º, so it would be easier to understand and store it:

public void rotateScroll(int amount) {
    int direction = (amount > 0) ? 1 : -1; 
    this.rotate(direction *2.5f);

    float newAngle = (float) Math.atan2(this.up.x, this.up.y)*MathUtils.radiansToDegrees;

    newAngle = (newAngle <= 0 && newAngle < -180) ? -newAngle : 360 - newAngle;
    this.rotationAngle = (newAngle / 360 >= 1) ? newAngle - 360 * ((float) Math.floor(newAngle / 360)) : newAngle;

    this.update();
}

Then, I calculate the angle of the mouse pan direction with the rotated y axis (alpha), turn it into a oº to 360º format and calculate the new deltaX and deltaY:

public void pan (float startX, float startY, int screenX, int screenY) {
    float deltaX = (- screenX + startX) * this.zoom;
    float deltaY = (- startY + screenY) * this.zoom;

    float alpha = (float) Math.atan2(deltaX, deltaY)*MathUtils.radiansToDegrees;

    alpha = 180 + ((alpha / 360 >= 1) ? alpha - 360 * ((float) Math.floor(alpha / 360)) : alpha);

    float newAlpha = (this.rotationAngle <= alpha) ? alpha - this.rotationAngle : alpha - 360 - this.rotationAngle; 

    float length = (float) Math.sqrt(deltaX * deltaX + deltaY * deltaY);

    float nDX = length * (float) Math.sin(Math.toRadians(newAlpha));
    float nDY = length * (float) Math.cos(Math.toRadians(newAlpha));

    this.translate(-nDX, -nDY);

    //Pan limits
    this.position.x = MathUtils.clamp(this.position.x, (float) (map.getMinX()-200),(float) (map.getMaxX()+200));
    this.position.y = MathUtils.clamp(this.position.y, (float) (map.getMinY()-200),(float) (map.getMaxY()+200));

    this.update();

}

It works, but most of this code is just converting angle formats and I'm sure it could've been done in a simpler way. If anyone finds a way to simplify it, I'd apreciate if you'd let me know!