What I need to do is create a long laser beam (suppose the object is 200px long) behind a turret, but move it a little to the right until the edge of the laser beam matches the edge of the turret, the laser beam should be invisible. However, as soon as the object is created it immediately starts to move but only a part becomes visible and increases. In fact, the ideal would be to be able to make an image half transparent and half normal if you could, but I don't know how. However I had not used the "DrawingCanvas" tool yet, I have now seen that it allows you to make only part of the px of different color, I have yet to see how it works but the point is that I should make an image only partially transparent and the transparency spreads in 'image. Or if you could create an invisible object but that when other objects pass over it they too become invisible (only in the overlapping part).
In any case I don't want to go from one frame to another, but rather make sure that the animation is continuous, for example the arc should be a simple straight line, which slowly curves and then comes back straight. Maybe with the DrawingCanvas tool I can solve the problem.
Another question, is it possible in one action to select (why would I need it now with the DrawingCanvas tool) multiple numbers at once? That is, if I can select in an image of 200px x 50px the part from 100 onwards for the whole height, I can make it transparent and then continuously modify 101,102,103 etc ... and the image becomes all visible. How can I simply select all numbers from 50 to 100 in one action?