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Snap grid and map grid match only sometimes

DragondogDragondog
in Mapping with ProFantasy's Software
I'm working on a map, a floorplan using the 1930s Travel Guide from The Cartographer's Annual April 2011. As I want to be able to snap to grid and have a matching vertical hex grid on the map, I created the snap grid the way I wanted it and I used Draw > Hex or Square Overlay... to get the hex grid on the map to match it. Or so I thought. It matches on the left edge of the map, but 300 hexes further to the right, the hex grid on the map has moved slightly and no longer matches the snap grid. Thus a straight line that cuts a hex on the map in half through the middle on the left edge of the map, 300 hexes later doesn't go through the middle of the hex.

How can I solve that?

Edit: Checking the map in more detail, I can see that this starts less than 30 hexes from the left edge of the map, but at that point it is barely visible, unless you know what you're looking for.
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  • DogtagDogtag Moderator, Betatester Traveler
    edited January 2014
    Posted By: Dragondog... I want to be able to snap to grid and have a matching vertical hex grid on the map, I created the snap grid the way I wanted it and ... It matches on the left edge of the map, but 300 hexes further to the right, the hex grid on the map has moved slightly and no longer matches the snap grid.
    This is just a guess, but I think hex grid distance is measured from side to side, not point to point. If so a, say, 30 mi hex grid will not horizontally match a 30 mi square editing grid because the distance from the middle of each hex will be slightly more than 30 mi (community member — and all-around math wizard — Joachim de Ravenbel could probably tell you exactly how much off the top of his head). Presumably, the grids should maintain a steady alignment vertically. Unless, of course, you set your editing grid to a rectangular shape, rather than square, to account for this. Again, this is just a guess. Perhaps someone else on the board can confirm or correct that guess.
    Posted By: DragondogThus a straight line that cuts a hex on the map in half through the middle on the left edge of the map, 300 hexes later doesn't go through the middle of the hex.
    I'm having trouble picturing this accurately. Any chance you can post a screen shot to illustrate?

    Cheers,
    ~Dogtag
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  • Joachim de RavenbelJoachim de Ravenbel Surveyor
    Posted By: DogtagJoachim de Ravenbel
    Speaking of the devil...

    I can reproduce the effect (see below). It probably has something to do with rounding because the distance between opposite vertices of a regulare hexagon is its width times 2 over the square root of 3 (about -about!- 1.1547).
    Depending on the grid spacing (width of the hexagons) AND the number of hexes, a small shift may happen. When you have hundreds of hexes, the small shift gets bigger and bigger...
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  • Joachim de RavenbelJoachim de Ravenbel Surveyor
    You can check the precision of the grid by using the info->distance (function key F8) tool between the top left and top right nodes and if you get a y-value as in the examples below, you will get a shift equal to this value multiplied by the number of hexes in width.
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  • Joachim de RavenbelJoachim de Ravenbel Surveyor
    edited January 2014
    If you really need more accuracy, as a work around I can suggest the following :

    1. Add the hex overlay
    2. Make the GRID sheet current and hide all other sheets
    3. Save
    4. Explode the grid
    5. Erase , right-click All, right-click Not, right-click Entity Type -> 2D Text , right-click Do it
    (Step 5 will keep the hex labels which are luckily at the right place)
    6. With the Snap button down draw a path made of the four sides of an hexagon as shown below.
    7. Copy this path
    8. Use the Rectangular Array to duplicate the pattern (you may have to work in steps here, I got a crash while wanting to get all the hexes in one go).
    9. Erase/Trim overlapping lines.

    Note: if you don't need labels, replace steps 4 and 5 by Erase the overlay (you still need to create it to get the grid snapping).
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  • DogtagDogtag Moderator, Betatester Traveler
    edited January 2014
    Posted By: Dogtag... community member — and all-around math wizard — Joachim de Ravenbel could probably tell you exactly how much...
    See? image

    I think I've learned more math and geometry from JdR's posts than I did in high school! image
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  • DogtagDogtag Moderator, Betatester Traveler
    edited January 2014
    Would that be considered a "horizontal" hex grid, or do the horizontal- and vertical- refer to the vertices rather than how the hexes stack? image
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  • Joachim de RavenbelJoachim de Ravenbel Surveyor
    Posted By: DogtagWould that be considered a "horizontal" hex grid, or do the horizontal- and vertical- refer to the vertices rather than how the hexes stack?image
    The question is quite relevant because the example above is considered a vertical hex grid within CC3 but the spacing is the horizontal width! image
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  • DragondogDragondog
    Posted By: DogtagWould that be considered a "horizontal" hex grid, or do the horizontal- and vertical- refer to the vertices rather than how the hexes stack?image
    I don't make maps very often, but when I do I usually pick the wrong hex grid because of this. In CC3 they go by the vertices, while it would be more natural to me to go by how they stack.
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  • DragondogDragondog
    edited January 2014
    Posted By: Joachim de RavenbelIf you really need more accuracy, as a work around I can suggest the following :

    1. Add the hex overlay
    2. Make the GRID sheet current and hide all other sheets
    3. Save
    4.Explodethe grid
    5.Erase, right-clickAll, right-clickNot, right-clickEntity Type -> 2D Text, right-clickDo it
    (Step 5 will keep the hex labels which are luckily at the right place)
    6. With theSnapbutton down draw apathmade of the four sides of an hexagon as shown below.
    7.Copythis path
    8. Use theRectangular Arrayto duplicate the pattern (you may have to work in steps here, I got a crash while wanting to get all the hexes in one go).
    9.Erase/Trimoverlapping lines.

    Note: if you don't need labels, replace steps 4 and 5 byErasethe overlay (you still need to create it to get the grid snapping).
    That worked perfectly. Thanks!
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  • DragondogDragondog
    edited January 2014
    I tried to do the whole map, it took anywhere between 1 to 10 minutes to get it done, but it worked. Lets see if I remember to check more frequently on the other floors of the building.

    Edit: After another level, it took less than 5 minutes.
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  • Joachim de RavenbelJoachim de Ravenbel Surveyor
    Posted By: DragondogThat worked perfectly. Thanks!
    You're welcome, glad it worked!
    You could perhaps put the whole grid on a frozen layer to prevent moving it.

    Posted By: DragondogAfter another level, it took less than 5 minutes
    And if you hide all the other layers or sheets, you can use the Clipboard copy to copy the grid to another map.
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  • DragondogDragondog
    edited January 2014
    Posted By: Joachim de Ravenbel
    Posted By: DragondogThat worked perfectly. Thanks!
    You're welcome, glad it worked!
    You could perhaps put the whole grid on a frozen layer to prevent moving it.
    Good idea!

    Apparently I'm using 130,636 items in my hex grid.
    Posted By: DragondogAfter another level, it took less than 5 minutes
    And if you hide all the other layers or sheets, you can use the Clipboard copy to copy the grid to another map.
    Perhaps I remember that the next time I need to do this.
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  • Joachim de RavenbelJoachim de Ravenbel Surveyor
    Posted By: Joachim de RavenbelApparently I'm using 130,636 items in my hex grid.
    More or less the same number of entities as by the Overlay only they were grouped in one global entity (which you can still do too).
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  • DragondogDragondog
    edited January 2014
    Posted By: Joachim de Ravenbel
    Posted By: Joachim de RavenbelApparently I'm using 130,636 items in my hex grid.
    More or less the same number of entities as by the Overlay only they were grouped in one global entity (which you can still do too).
    Strange. That was the number of items I got when moving it to its own layer. Now that I plan to group them, I suddenly have 258,841 items. And in both cases it was only supposed to be the hex grid itself.
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  • Joachim de RavenbelJoachim de Ravenbel Surveyor
    edited January 2014
    The number labels are already on the Hex Grid layer, so they add up to the paths.
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  • DragondogDragondog
    Posted By: Joachim de RavenbelThe number labels are already on the Hex Grid layer, so they add up to the paths.
    I wondered if that was the case. Thanks for confirming that.
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