File content as of revision 21:edfeb289b21f:

#include "uLCD_4DGL.h"
#include "bullet.h"
#include "game_synchronizer.h"
#include "misc.h"
#include "math.h"

extern Game_Synchronizer sync;

Bullet::Bullet(Tank* t) {
    tank = t;
    speed = 30;
    in_flight = false;
}
void Bullet::shoot(void) {
    if(in_flight) {return;}
    time = 0;
    tank->barrel_end(x0, y0);
    x = x0; y = y0;
    vx0 = speed*cos(tank->barrel_theta);
    vy0 = speed*sin(tank->barrel_theta);
    in_flight = true; 
}

void Bullet::update_position(float dt) {
    if(!in_flight) { return; }
    time += dt;
    x = x0 + vx0*time;
    y = y0 + vy0*time + 0.5*(-9.81)*time*time;
}

// return codes:
//      BULLET_NO_COLLISION: no collision
//      BULLET_OFF_SCREEN:   off the side of the screen
//      Otherwise, returns the color you've hit in 16bpp format. 

int Bullet::time_step(float dt) {
    if(!in_flight) { return BULLET_NO_COLLISION; }
    int old_x = x;
    int old_y = y;
    
    update_position(dt);
    
    if(x == old_x && y == old_y) {
        return BULLET_NO_COLLISION;
    }
    
    if(x < 0 || x > 128 || y < 0 || y > 128) {
        sync.pixel(x, y, SKY_COLOR);
        in_flight = false;
        return BULLET_OFF_SCREEN;        
    }
    
    int col = sync.read_pixel(x, y);
    if(col != CONVERT_24_TO_16_BPP(SKY_COLOR)) {
        sync.pixel(old_x, old_y, SKY_COLOR);
        sync.filled_circle(x, y, 4, SKY_COLOR);
        in_flight = false;
        return col;
    }
    sync.pixel(old_x, old_y, SKY_COLOR);
    sync.pixel(x, y, BLACK);
    return BULLET_NO_COLLISION;
    
}