Sectors:  circular sectors

 Circular sectors:  in general

Here is a really simple way to make circular sectors. You most likely do not want your rotating sector to wobble so you might want to consider this way of making circular sectors. I find this method to be the best. Back when I first starting building Maps, no one could tell me a good way of making circular sectors or why you couldn't make one outside of one that had already been made. Now, I pass on to you what I have discovered about circular sectors. ;)


 Circular sectors:  creating

If you haven't seen the section on creating a sector outside of one that has already been created, you may want to read up on it: surrounding sectors. The reason you cannot make a sector outside an existing one is because the engine treats it as a sector that is higher or lower on the Z plane. The weirdness that results in the display of those sectors is because the sectors are not at different Z coordinates; they are in the same spot. The reason I mention this is because the same goes for circular sectors: the outer most sector must be created first and you will notice this in the following images.

The following steps are done in 2d mode
Have a look at the following screen captures. These images show the various steps in making a circular sector keeping the aforementioned in mind. Decide where in the parent sector you want the circular sector(s) to be and draw a line from one wall to the opposite wall (add vertices if needed - you can delete them later). Place two vertices on this new line; they will be the start points for the first half of your circle. Make sure that those two points are placed on that line an equal number of grid squares apart (this will make it real easy to find the exact center if you were to make it a rotating sector). Once the first half is in place, (you do that by holding the cursor between those two points and pressing the C key), redraw the line between those initial two points. You have to redraw that line because after using the C key to draw the first half of the circle, the line is removed in the process. Screens one through five show the steps just mentioned.



Screen five is where you could stop if all you want is one rotating sector. All that would be left to do is join the two halves of the parent sector (the two halves outside the circle) and remove the initial anchor vertices you may have added to the walls. This would make the circular sector its own sector and you only have to add the sprites needed to make it rotate. If one rotating sector is all you want, place a sprite in the center (very easy to do) and give it an unique hitag and a lotag of 1. Place another sprite within the circle but away from the center and give it the same unique hitag and leave its lotag at zero. Just make sure that the tails are positioned in the opposite direction of each other. That is, if the central sprite's tail is facing North, then make the second sprite's tail face South. If you want the player to spin with the sector when he steps on it, place the cursor on the floor of rotating sector (in 3D mode) and press the R key.


Carrying on in 2D Mode:   making another circular sector within the one just created
Screen six shows the next step in making another sector within the one made in screen five. Say you want a water well and you want a bit of wall around the well. You would need another circular sector inside. Redraw the line through the center like we did in screen four and this time make the grid size smaller so that you can place two new initial points (see screen six). Screen seven shows the first half of the inner sector. Redraw the center line, again, (see screen eight), and create the other half of the inner circle (screen nine shows the completed inner circle).
 
The image to the left depicts what the area might look like after you have rejoined the two halves of the parent sector and joined the halves of the circular sectors. Theoretically, you could keep on doing the above steps to create more inner circular sectors. I'm not sure of how many you could make before "ghost" sectors started to appear or the engine didn't want to display them properly...but you can try. I have not extensively tested the limitations of this method but I have made as many as five inner sectors for various effects in the bonus level for Critical Mass. You can try to make as many as you like. Just remember to save your map between steps in case something should go wrong so that you can easily back track if you need to.


notes:
  • With this method, it's probably easier to recreate another circular sector instead of trying to copy and move one. However, if you have an elaborate number of circular sectors all part of one structure, you could make a temporary square sector around them and then move the whole lot at once. When you get the sectors copied and moved, you would only have to trace the square sector instead of the million points in the outer most circular sector. I'll show you how in the "more on circular sectors" section of these tutorials.
  • If drawing a line (splitting the parent sector) from one wall to the other will be a problem due to the design of the area, you can create a temporary, square sector in which you can split so that you can create the circular sector using the method described above. Once the circular sector(s) is created you can then just join the parent sector with the temporary square sector.
  • The grid size can be changed at any time before, after or during any process.