SDLPP: add constant rotation

sdlpp/sdlpp_renderobject.cpp

@@ -291,6 +291,16 @@ void RenderObject::rotateClockwise( int angle ) {
 void RenderObject::rotateCounterClockwise( int angle ) {
     rotateClockwise( 360 - ( angle % 360 ) );
 }
+void RenderObject::setRotationSpeed(int speed) {
+    rotation_speed = speed;
+}
+void RenderObject::startRotation() {
+    rotating = true;
+}
+void RenderObject::stopRotation() {
+    rotating = false;
+}
+
 Vec2D< double > RenderObject::computeAlignmentAdditions() {
     double x_addition = 0;
     double y_addition = 0;
@@ -322,4 +332,10 @@ void RenderObject::updateXY() {
     current = { original.getX() + additions.getX(),
                 original.getY() + additions.getY() };
 }
+void RenderObject::custom_move(int ticks) {
+    if(isRotating()) {
+        auto angle = ticks * rotation_speed / 1000; // tick = millisecond
+        rotateCounterClockwise(angle);
+    }
+}
 } // namespace SDLPP