Since it''s a side-scroller I''m guessing that it''s also a platform type, yeah ?

Anyway, there are loads of methods, but here is one I used and It''s probably the fastest, or it doesn''t take too much processing. If you are using 256 colour (8-bit) then it''s handy.
Use your palete of colours and give them an order, say green (grass) is "walk", blue (water) is "nowalk", then...

if(player.position "nowalk")
{
if(player.going forward)
player.position--;
else
player.position++;
}


Hope this helps
djsomers

Oops!

Just saw the ''Tile'' bit in your post.

That makes thinks more simple, Give each tile type a value..

     struct tile   {      int width;      int height;      etc..      const char *walkability;   };  

Now in your game loop:
do before blitting your sprite to mem/screen

        if(player.pos==tile[x][y] && tile[x][y[y].walkability="nowalk"){   don''t move player sprite;}  

This is better and relly just as fast in tile games.

djsomers

when you check for walkability, you need to make sure that the player''s position is set to the top pixel of the tile they are walking on. that''s what your problem is in the screenshot. if i had time, i would pull up my engine code and give you some calculations on how to do that, but it really isn''t all that hard anyway. just set the player''s position to where his feet are touching the top of the tile he''s standing on.

sorry i couldn''t explain more...

dave

--
david@neonstar.net
neonstar entertainment

If your character is "below" where he/she/it should be standing, then you have a problem with which tile your comparing to be "solid". Play with the y (or x, whichever is the "up/down") and see how it needs to be offset to check the tile.

    if (map[player.posx + world_camerax / TILE_SIZE][player.posy + TILE_SIZE + world_cameray / TILE_SIZE] == 0){//player isn''t standing on something keep falling}else {//player is standing}    

Note the +TILE_SIZE in the y dimension of the map array. This shifts our view to UNDER the player, instead of the map[][] your player was being drawn at.

Another really nice thing is that you have blank space set to 0- do you have any other "background/walkthrough" tiles in mind? If so, excellent! Try numbering them so that the first few (0-10 for example) are the walkable ones, and the others (11+) are the "solid/impassable" ones. Then change your "== 0" to a test for "walkable" things "< 11" and you can walk/fall through coins, illusionary walls, fake ground, et cet.

-Tok


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well heres how I do it. Don''t know if it helps or not.
all tiles are 32x32 pixels.
Each tile has a blocking byte which is or''d to various constants I''ve defined.
so bit one is block up, bit two block east.
#define TILE_BLOCK_UP 1
#define TILE_BLOCK_RIGHT 2
#define TILE_BLOCK_BOTTOM 4
#define TILE_BLOCK_LEFT 8
#define TILE_BLOCK_ALL (TILE_BLOCK_UP | TILE_BLOCK_RIGHT TILE_BLOCK_BOTTOM | TILE_BLOCK_LEFT)

my character has a velocity x and a velocity y, in pixels.
To handle falling, _every_ frame we add gravity to the y velocity (see why later).
Characters have a width (in tiles) and a height(in tiles)
I the character''s position is tracked by the bottom left corner of it''s bounding rect.
I have a function to convert screen pixels into world coordinates.
A world coordinate is given by tilex, tiley, subtilex, subtiley;
The camera maintains a camera x, y and sub x, y to allow for smooth scrolling.
So I first calculate the world coordinates of the current tile I''m in.
I then calculate the world coordinates of the tile I''m travelling to. Based on the velocity of course.
I also calculate the world coordinates of all four bounding points of the character. East from the bottom left, I just add the character''s width and height.
Then depending on the direction of the velocity I do some checks.
example:
if(velocity.x < 0) //moving left
(
//check if the left edge has crossed a tile boundary
if(bottomleft.starttile.x != bottomleft.endtile.x)
{
if(World.GetTile(bottomleft.x,bottomleft.y)->GetBlocking()
&& TILE_BLOCK_RIGHT)
{
SetXVelocity(0) //stop moving in the x direction
SetXPosition(bottomleft.starttile, 0) //far left of start tile
}
else
{
//add x velocity to current x
}
}
)
else //moving right etc...

So that handles left and right motion pretty simply.
Y motion is pretty much the same
if(velocity.y < 0) // we''re falling. we should _always_ be falling
{
if(bottomleft.starttile.x != bottomleft.starttile.y)


}