C Language

#include #include #include #include #include #include #include #include #include

// (Task 1) Define a function called pixel_level_collision which detects whether // two sprites s1 and s2 collide at pixel level. The function must be able // to work correctly even if the ZDK screen has not been set up, and should // make no attempt to use any function or variable declared in // , either directly or indirectly. // // Parameters: // s1 - the address of a Sprite which has been initialised and placed at // arbitrary position on the screen. // // s2 - the address of a Sprite which has been initialised and placed at // arbitrary position on the screen. // // Returns: // A boolean value which is true if and only if there exists a point (x,y) // which is opaque in both s1 and s2. // // Definition: (x,y) is opaque in sprite s if and only if: // 0 x)) width, and // 0 y)) height, and // offset(s,x,y) = sy * s->width + sx, and // s->bitmap[offset(s,x,y)] != ' '.

INSERT RETURN_TYPE FUNCTION_NAME ( PARAMETER_LIST ) { INSERT CODE HERE }

char * cross = "y y" /**/ " y y " /**/ " y " /**/ " y y " /**/ "y y" ; char * plus = " z " /**/ " z " /**/ "zzzzz" /**/ " z " /**/ " z " ;

int main( void ) { setup_screen(); sprite_id s_cross = sprite_create( 20.9, 8.3, 5, 5, cross ); sprite_id s_plus = sprite_create( 30.9, 17.9, 5, 5, plus );

while ( true ) { clear_screen(); sprite_draw( s_cross ); sprite_draw( s_plus ); if ( pixel_level_collision( s_cross, s_plus ) ) { draw_string(0, 0, "Pixel-level collision has been detected!"); } show_screen();

int key = wait_char();

if ( key == '2' ) { s_plus->y++; } else if ( key == '8' ) { s_plus->y--; } else if ( key == '4' ) { s_plus->x--; } else if ( key == '6' ) { s_plus->x++; } else if ( key == 'q' ) { break; } }

cleanup_screen();

return 0; }

Figure I: /cygdrive/a/temp 3 Use the numeric keys to move the plus sprite around, as seen in Figure 2 Figure 2 /cygdrive/a/temp yy z y yz The plus sprite can nestle in very close to the cross without triggering a collision detection, but when it does, a message is displayed (Figures 3, 4, 5)