8 replies to this topic

[ivansla]

Hi guys!

I'm trying to create a hexmap based game, like Panzer General, well actually I'm trying to animate unit movement.
And this is where I have problem. I am using A* algorithm to determine the path, so that is not problem.
My problem is that image I'm animating is always a couple of pixels on X-axis late.

This is how I calculate the movement:

	 int SPEED = 1;
	 int SOUTH_EAST = 300;
	
	double newX = Math.cos(Math.toRadians(SOUTH_EAST));
	double newY = Math.sin(Math.toRadians(SOUTH_EAST));
	this.speedX = SPEED * newX;
	this.speedY = -SPEED * newY;
	 ....
// later in code inside each frame
this.x += this.speedX;
this.y += this.speedY

// drawing of image inside each frame
g.drawImage(this.tileImage, (int) this.x, (int) this.y, (int) this.x + TILE_SIZE, (int) this.y + TILE_SIZE, frameX, frameY, frameX + TILE_SIZE, frameY + TILE_SIZE, observer);

The problem is that those 300 degrees is from 0,0 to 39,39 (My tile size is 40) which is diagonal of the square inside which the hexagon is, and I need a little sharper angle since I'm not working with squares but hexagons. Ok, I know I need to provide correction for x and y, but that is not the point, point is that my movement by X-axis is late and if I put the angle of 305 that is too much.

Well my question is, how am I suppose to animate the unit movement from one hextile to another?
Is my approach good and I just need to do a better math calculation (I'm terrible in math, BTW) or is there some other approach?

[Tom KQT]

Hi,
I'm trying to visualise your problem, but I'm failing at it
How is your hex grid oriented? Do the hexes form straight rows (x axis) or columns (y axis)? How do you measure the angle 300?
A little simple picture would help a lot.

Tom

[ivansla]

Hi Tom, thanks for the reply.
Here's the picture you asked.


I imagine there is a circle inside the hexagon. and since all the sides are the same I just divide 360 / 6. and I get 60 degrees for each direction.

[Tom KQT]

The angle -60 (or 300) should be absolutely fine and accurate.

You say the movement is behind only on the x axis? It reaches a point located left of the desired target point? I really cannot imagine how would that happen. Is the grid drawn properly, isn't the problem actually with how the grid looks and not with the movement?

Or, is it possible to make some screenshot of the exact problem you are getting?

[ivansla]

Ok, Tom, for better visualization, I decided to upload my project. it contains source as well it's in Java, if you just want to run it, you can do it by double clicking.
http://rapidshare.com/files/1778542098/hex-tutorial-src.jar.

As you can see, the tank is not inside in exact hex tile, but is out of bounds. and the lower it get the bigger error it has.

[Tom KQT]

The hexes definitely aren't rendered properly, they are stretched - they are too wide. You cannot draw an inscribed or circumscribed circle in/around the hex.

I think the tank moves properly (it seems so but it's hard to tell), but the displayed hex grid doesn't correspond to it, the tiles are too short vertically, thus the tank ends far away below.

EDIT:
When I'm examining your grid more, I think I know what you did wrong. It seems that you misunderstood how a hex should look like.
Check the picture, left side shows how it should look, right side is your case.
Drawn in red is an inscribed circle and in green a square - you managed to fit your hex into a square, but that's not right ;)

http://www.freeimagehosting.net/xz5x9

[ivansla]

Yes, Tom you are correct, I did it the way showed on the right side.
When I was reading following articles:
http://www.gamedev.n...aps-part-i-r747
http://www.gamedev.n...tile-maps-r1800

I got the impression that's how it's suppose to be. Especially the second one.

So, in order to fix my problem, I need to draw smaller tank or draw different hexes? Because my hexes are 40x40 px.
I thought that when I draw a hex into square, the hex will have all sides the same. In your case certain sides of the hex are bigger than others.

[ivansla]

Ok I found this article: http://gdreflections.com/2011/02/hexagonal-grid-math.html.
So Tom, thanks for showing me my error. Since I have poor mathematical background no wonder.
I will try to redraw the hexes.

[Tom KQT]

I'm glad I could help. Please let me know when you get it working right, or feel free to ask should you have any further questions/problems.