stationary objects when dynamically scrolling
BlitzPlus Forums/BlitzPlus Beginners Area/stationary objects when dynamically scrolling
| ||
| I have a 2d game and I am using a tileset to dynamically scroll in all directions. Just wondering is there a tutorial or something about placing stationary objects on my map. That is to say my guy walks around just fine and the screen scrolls but what if I want to put in a building or a rock or something. how do I keep track of where to draw it when scrolling? I guess legend of zelda would be an example of what I'm trying to accomplish here. |
| ||
| I assume you are keeping a record like in a type for instance of what the properties of the object are such as: type stuffinthegame field worldx,worldy field health field class$ ; building, rock, player etc end type and then all you need to do is keep track of where the upper left corner pixel is in the world with a pair of variables 'cornerx, cornery' for instance and then when drawing all objects simply subtract the cornerx,cornery from the object's worldx,worldy - if the resulting value is within the boundaries of the screen then it can be drawn. |
| ||
| I apolagize at the moment I've been developing in Dark Basic Pro (I like the community here better) but you'll get the idea. From your post I guess I could use my constants GAMEWORLDWIDTH and GAMEWORLDHEIGHT to figure out where I am here is what I am doing I got alot of it from a dark basic pro game development book this is a bit long say I have a bitmap composed of 10 different ground tiles then I have a data file that is like data 1,5,6,7,8 data 1,34,7,8 blah blah blah then I load all this stuff into my array (perhaps a solution to your post :) ` load the tile images load bitmap "groundtiles.bmp", IMG_TILES `create the scroll buffer surface in memory, slightly bigger than the screen create bitmap IMG_SCROLLBUFFER, SCROLLBUFFERWIDTH, SCROLLBUFFERHEIGHT `load the map data into the array for y = 0 to MAPHEIGHT-1 for x = 0 to MAPWIDTH-1 read MAPDATA(x,y) next x next y in my main loop I have two methods I keep calling update the scrolling view UpdateScrollPosition() `draw tiles onto the scroll buffer DrawTileMap() here is a piece of the update scroll position function UpdateScrollPosition() `scroll based on mouse input if hunter.x < 200 and ScrollX <> 0 hunter.x = 199 dec ScrollX, hunter.speed - 2 hunter.frame = getframe(hunter) hunter.inactive_timer = 0 endif if hunter.x > 400 and ScrollX <> GAMEWORLDWIDTH - WINDOWWIDTH hunter.x = 401 inc ScrollX, hunter.speed - 2 hunter.frame = getframe(hunter) hunter.inactive_timer = 0 endif and a couple more if then statements for the y position of the hunter then I do then I do `update horizontal scrolling position and speed if ScrollX < 0 ScrollX = 0 else if ScrollX > GAMEWORLDWIDTH - WINDOWWIDTH ScrollX = GAMEWORLDWIDTH - WINDOWWIDTH endif endif `update vertical scrolling position and speed if ScrollY < 0 ScrollY = 0 else if (ScrollY > GAMEWORLDHEIGHT - WINDOWHEIGHT-1) ScrollY = GAMEWORLDHEIGHT - WINDOWHEIGHT-1 endif endif here is the draw tile map function `*************************Draw Tile Map***************************************************** `This function fills the tilebuffer with tiles representing `the current scroll display based on scrollx/scrolly. function DrawTileMap() `calculate starting tile position tilex = int(ScrollX / TILEWIDTH) tiley = int(ScrollY / TILEHEIGHT) columns = int(WINDOWWIDTH / TILEWIDTH) rows = int(WINDOWHEIGHT / TILEHEIGHT) `draw tiles onto the scroll buffer surface for y = 0 to rows for x = 0 to columns `retrieve the tile number from this position tilenum = MAPDATA(tilex+x, tiley+y) `draw the tile onto the scroll buffer DrawTile(IMG_TILES,tilenum,TILEWIDTH,TILEHEIGHT,16,IMG_SCROLLBUFFER,x*TILEWIDTH,y*TILEHEIGHT) next x next y `draws the portion of the scroll buffer onto the back buffer `according to the current "partial tile" scroll position. left = ScrollX MOD TILEWIDTH top = ScrollY MOD TILEHEIGHT `set dimensions of the source image as a rectangle right = left + WINDOWWIDTH bottom = top + WINDOWHEIGHT `draw the partial tile scroll window onto the back buffer copy bitmap IMG_SCROLLBUFFER, left, top, right, bottom, 0, 0, 0, WINDOWWIDTH, WINDOWHEIGHT endfunction here is the draw tile method that draw tile map calls it just draws the tile to the screen `This function does the real work of drawing a single tile from the source image `onto the tile scroll buffer. Parameters provide much flexibility. function DrawTile(source as integer,tile as integer,width as integer,height as integer,columns as integer,dest as integer,destx as integer,desty as integer) `describe the source image left = (tile MOD columns) * width top = (tile / columns) * height right = left + width bottom = top + height `draw the tile copy bitmap source, left, top, right, bottom, dest, destx, desty, destx+width, desty+height endfunction |
| ||
| Perhaps if you are using an array you could add an extra dimension to the array "MapData(X,Y,Layer)". The 'Layer' elements of the array would hold a number of things like this for instance: MapData(x,y,0) -> this holds the tiles in much the same way as you are currently doing MapData(x,y,1) -> this holds the ID number or handle of the 'creature'/'building' etc that is within that tile. Then you simply use a similar technique to what you have above to draw the building/creature. However - using the method I've just given you will only allow you to have one object per tile which is most likely not what you want. Instead you could do this: MapData(x,y,1) -> this holds the handle to a 'bank' containing a list of handles of objects within that tile. You then just have to remember to update the bank and the array whenever a creature/building moves from one tile to the next. Hope that is of some help. |
| ||
| Thanks, I like that idea |
   |