Map buffer
Definition
POINTER map_buffer ( <INT fileID> , <INT graphID> )
Get access to the memory buffer of the map. This function is usefull in combination with Memset(). This way you can manipulate the actual bytes of the map.
Parameters
| INT fileID | - The file that holds the graph. |
| INT graphID | - The graph to get information from. |
Returns
POINTER : Pointer to the memory contents of the map.
Example
In this example I'm going to demonstrate how you can manipulate the pixel buffer of the map. I load the same map twice (each with their own ID), and one of them is butchered by messing with it's pixel buffer. By assiging that map to a Pointer with map_buffer(), we can use Memset() to change the bytes in the memory area that the map occupies.
IMPORT "mod_say";
IMPORT "mod_debug";
IMPORT "mod_key";
IMPORT "mod_map";
IMPORT "mod_video";
IMPORT "mod_wm";
IMPORT "mod_draw";
IMPORT "mod_screen";
IMPORT "mod_mem";
IMPORT "mod_text";
GLOBAL
int map_id; // id code of the map to load
int map_id2;
pointer p_map; // pointer to the map_buffer
PROCESS main();
BEGIN
set_mode(320,200,32);
write(0,10,10,3,"map_buffer example, press 'ESC' to quit.");
write(0,10,30,3,"press '1' to show the modified map.");
write(0,10,40,3,"press '2' to show the orginial map.");
// load two maps, this map can be found in bennupack: 2 Medium\IA\PATH.FIND\3COCHE.MAP
// it is a the "car" graphic of the pathfind tutorial for TYCO. Both maps are the same,
// but one of them we're going to modify with map_buffer().
map_id=load_map("3COCHE.MAP");
map_id2=load_map("3COCHE.MAP"); // same map, but this one is left intact
graph=map_id2; // original map
x=100;
y=100;
// get the memory adress of the "raw" pixel buffer of the map.
p_map=map_buffer(0,map_id);
// now that we've got acccess to the pixel buffer, we can change individual bytes.
// with memset we can modify memory contents of individual bytes.
// in this case, we change the first 1000 bytes into the color #100.
memset(p_map,100,1000);
// no, we're offsetting 200 adresses from the start of the memory block, and change another
// 1000 bytes into a different color.
memset(p_map+200,150,1000);
LOOP
IF (key(_esc))
BREAK;
END
IF (key(_1)) // show the "butchered" map
FRAME(100);
graph=map_id;
say("showing map modified with map_buffer()");
END
IF (key(_2)) // show the original map
FRAME(100);
graph=map_id2;
say("showing original map");
END
FRAME;
END
END
Used in example: Load_map(), Memset(), Write(), Say(), Pointer()
Notes
In the Memset() function, indiviual bytes are used. The amount of bytes to store the color of one pixel depends on it's colordepth. In 8 bit mode, you need only one byte per pixel, in rgb mode 3 bytes and in rgba mode 4 bytes per pixel. So that is something you should be aware of. This is a similair caveat as with the Alloc() function, because you're dealing with raw memory contents here.