OK. Just an update:
Pulling my hair out but here is what I should have done and what I have actually done.
Getting all the neighbors of the player and highlighting the tiles minus the obstacle tiles are pretty straight forward:
Because distance is the max absolute value of the three results (destination y - player y, destination x - player y, first result - second result),
I simply loop through all the hex tiles where the distance from the player is <= to the number of moves and highlight the tile except when it is an obstacle.
This still does not give me the correct distance around obstacles. The movement cost to tile differs when an obstacle is in line with one of the six sides of the hexagon. The cost increments with 1 for each tile after the obstacle tile in that direction. Obstacles diagonally in line on the points of the hexagon does not make a difference to movement cost.
The apparent easiest way to then rather calculate distance from the player keeping obstacles in mind, is to do a movement-limited flood fill. I really struggle doing this in Fusion. Seems like using something like Unity is the way to go - but I am not going to learn C# now.
So my very long workaround is this: I get all the obstacle tiles in the movement range from the player and note all their info in an array. Here is another snag: Obstacles diagonally (on the pointy sides of the hexagon) should be excluded. It took me a while, but there are only 4 directions that needs to be taken in account and because these diagonals differ with y+2 and only x+1 (depending on direction), I could exclude tiles where (Hex y - player y)*2 = Hex x - player x and derivatives of that depending on the direction.
Then for each of the (now valid) obstacle Hex tiles, I add a movement cost of 1 for each hex behind the obstacle tile in the respective directions and run my loop as before but just adding the cost.
So I had: On loop Max(Max(Abs(r1), Abs(r2)), Abs(r3)) < player movement and Hexid=Loopindex and Hex is not an obstacle, highlight tile
Instead I will run: On loop Max(Max(Abs(r1), Abs(r2)), Abs(r3))+movement cost < player movement and Hexid=Loopindex and Hex is not an obstacle, highlight tile
Now I have the correct cost, direction and all available tiles that can be moved on, according to movement, highlighted - yah!
Next will be movement - No idea when I will get there: The idea is simple in that the highlighted tile you click will be the destination and the player the source - From there, determine the lowest cost from destination to source. (I have most of this info already stored in an array) For each path tile mapped, reverse the direction so that your animation works correctly, walking from source to destination.
Implementation is another thing. I probably need to make use of a while loop, which I cannot get to work correctly in Fusion 2.5
Anyway - All of the calculations has got no bearing on actual pixel position and therefore it will not matter if you make an ISO grid or plain 2D, it will all work out the same.
After that, I suppose it will be attack distance and highlighting enemy units in range of the attack. Enemy AI will be the last to do (if I do) Will just be a versus game to start off with.
Perhaps have a peek to see where I can acquire some nice royalty free sprite sheets for friendly and enemy units - This would of course be on the D&D theme.
Information I Google make it sound so complicated - like bringing it across to someone that codes for an eternity - which is not me.
