Scratch

Here's one way to do (half) of it... just need an If in there to have it turn the other way if it needs to. I'll add that bit in if you need it.

point in direction (wherever)
set ($current_direction) to (direction)
point towards (other_sprite)
set ($new_direction) to (direction)
point in direction ($current)
set ($temp) to ($new_direction - $current_direction)
set ($remainder) to ($temp mod 10)
set ($temp) to [($temp - $remainder) / 10 ]
repeat ($temp) {
    wait 0.5 secs
    turn 10 degrees
}
wait 0.5 secs
turn ($remainder) degrees

Thanks MrWeston.  I think what you posted is the part i don't have trouble with ... but I'm very grateful for a reminder of the mod command.  It will always thrill me with its elegant usefulness, and its quality of never being thought of by me.

The problem tying me up is that if A is pointed 300 deg, and B is at 10 deg relative to A, then A will rotate -290.  Of course I want +70.  It's getting the difference ... it's like flying over the International Date Line. 

I think my daughter gave me the solution.  Set direction of A as relative bearing of 0.  The difference between relative bearing and A's direction is your diffCalculated.  You add the diffCalculated to the bearing of B.  The difference between the relative bearing of A and the relative bearing  of B is a number between 0 and 360.  If <180, go one direction; if >180, go the other. 

Give me a day to try things -- I'll post back with whatever worked.

if im correct, you want a turret to point to the mouse, but only 10 degrees to th left/right?

if(direction>80 and direction< 100){
point towards (mousePointer)
} else if (direction>100){
direction = 99
} else {
direction = 81
}

That should just about work. If you plan on rotating the turret mount, post it up and i'll fix it for you, it will take a quick script or two extra

My idea is this:

Use two sprites.

On the Stage, put a short broadcast script:

[blocks]<when[ Stage ]clicked>
<broadcast[ click [/blocks]

The second sprite must be hidden, and at the same position of the sprite you want to rotate. Put this:

[blocks]<when I receive[ click
<point towards( mouse-pointer [/blocks]

The main sprite should have this:

[blocks]<when I receive[ click
<wait( 0.05 )secsc> (to let the other sprite rotate, otherwise it couldn't work well)
<if><( <direction> <<> (direction of HIDDEN SPRITE) )>
<turn cw( -10 )degrees>
<end>
<turn cw( 10 )degrees>
<end>[/blocks]

I haven't tried that, but I guess it should work 

Thanks for the replies.  This was a difficult problem ... the first step was discovering that a sprite uses positive degrees for right, negative for left!  Which is obviously more useful than 0 to 360 for a full circuit, but it confused me. 

My implemented solution is found in "Buzzard Island":
http://scratch.mit.edu/projects/smandoli/398737

technoguyx and mariobrosrule:  This was like my son's solution (for his own game).  One problem is that the final direction never resolves on the target.  It twitches between almost-solutions, which was okay for my son's game but not for mine. 

yambanshee and technoguyx and mariobrosrule:  I didn't test, but I think none of these account for the target sneaking up from behind.  My turret has a limited detection range, so the target can appear at 179 degrees.  It means you must deal with any permutation of to-from, and correctly choose whether to rotate clockwise or counter-clockwise.   That ALSO was an issue for my son's solution. 

bhz:  Your solution is terrific (just going by the demo play).  Unfortunately your signature about '90% of teens' is troll-ish and this threw me enough that I actually overlooked the demo link you offered until just now.  Apologies.

Last edited by smandoli (2009-02-02 12:34:17)