Hello,
I am using Mappy with Allegro 5 to create and render my map however I am having trouble creating a working pixel perfect collision check for the walls.
The walls are flagged in mappy and I have a function set up to check:
#SelectExpand
1int Map::collided(int x, int y)
2{
3 BLKSTR *blockdata;
4 blockdata = MapGetBlockInPixels(x,y);
5
6 return (blockdata->user1);
7}
And I have checks for all directions, the up and down functions seem to be working perfectly however the left and right ones are not:
#SelectExpand
2bool Character::collideLeft
()
3{
4 int highX
= 0;
5 int highY
= 0;
6
7 if(p_Map->collided
(m_xpos, m_ypos
) || p_Map->collided
(m_xpos, m_ypos
+m_height-1
))
8 {
9 al_lock_bitmap(m_sys_bitmap,
al_get_bitmap_format(m_sys_bitmap
), ALLEGRO_LOCK_READONLY
);
10
11 ALLEGRO_COLOR pixel
;
12
13 for(int x
= m_frame_column
*m_width
; x
< (m_frame_column
*m_width
)+m_width
; x
++)
14 for(int y
= m_frame_row
; y
< (m_frame_row
*m_height
)+m_height
+1; y
++)
15 {
16 pixel
= al_get_pixel(m_sys_bitmap, x, y
);
17
18 if(pixel.a
> 0)
19 {
20 if(y
< highY
)
21 highY
= y
;
22 if(x
< highY
)
23 highX
= x
;
24 }
25 }
26
27 if(p_Map->collided
(m_xpos
+highX,m_ypos
+highY
))
28 {
29 cout
<< highX
<< ", " << highY
<< endl
;
30 al_unlock_bitmap(m_sys_bitmap
);
31 return true;
32 }
33
34 else
35 {
36 al_unlock_bitmap(m_sys_bitmap
);
37 return true;
38 }
39 }
40}
Now I have tried many methods and can see the flaws in the one above however this is the attempt I tried last, could anyone advise me on a simpler method, perhaps checking pixels on system bitmaps isn't the right way. It does work fine for collision between two other bitmaps though.
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