basic algo:
while (! quit)
{
drawscreen();
process_input();
}
drawscreen:
draw_tileset()
draw_map()
draw_mouse()
process_input:
getmouse(&x,&y,&b)
if (b !=1) return
if isin(x,y,0,0,50,50) set_brush(0); // set current "brush" to the first tile in the set.
else if isin((x,y,0,51,50,100) set_brush(1); // set current "brush" to the second tile in the set.
...
...
else if isin(coordinates for right half of screen) place_tile(x,y)
draw_tileset:
this just draws a bunch of tile sprites on the left half of the screen. since you're building a 2d engine, i assume you can draw a sprite <g>.
draw_map:
this draws the map on the right half of the screen. code will be a modified version of the code used to draw a map in the game. it will only cover half the screen, and will use the editor's map as input, instead of the game's map. you may be able to share map related code and/or data structures between the game engine and the editor.
draw_mouse:
this just draws the mouse (if you have to do it yourself)
getmouse:
this simply returns the current state of the mouse: x and y screen position, and buttons (0=none, 1=L_button, 2= R_button. so process_input returns immediately, unless the left mouse button is pressed
isin:
this returns 1 if the point x,y is in the area specified (such as 0,0,50,50). otherwise it returns 0.
place_tile:
convert x,y screen coordinates to x,y map tile coordinates.
set map tile x,y to the current brush value.
you'll probably want to add some buttons for load, save, quit, etc, or perhaps press ESC for a popup menu with those features.
a slick improvement over a basic stand alone editing tool would be one that you could add into a game to edit the game map in real time. you'd have a small wrapper app that used the editor module to make a standalone tool, and you could also link the editor module into the game app to get an in-game editor.
this is what i did with my limb based modeling and animation module. at first, i was going to build it as a stand alone editor for CAVEMAN. But duplicate data structures etc meant it was easier to make it a built-in editor. Later, i needed the modeler for another title, so i put it in its own source file that i can link into any app.
