no-reply@allegro.cc (KirbyDS11) — Mon, 24 Jun 2013 20:17:37 +0000

I'm having a problem picking up collisions with a bitmap that I have drawn to. I have a background class that will draw the land and a player class that draws the player and picks up the collision. But it won't pick up the collision where I add the bitmap to the land.

#SelectExpand
   1class Background
   2{
   3public:
  Background()
  {
      girder=al_load_bitmap("images/girder.png");
      gw=al_get_bitmap_width(girder);
      gh=al_get_bitmap_height(girder);
  }
  void load_map()
  {
      land=al_load_bitmap("images/testmap.png");
  }
  void drawland()
  {
      al_draw_bitmap(land,0,0,0);
  }
  void addgirder(int gx,int gy,ALLEGRO_DISPLAY *display)
  {
      //this is where the bitmap is drawn to the land
      al_set_target_bitmap(land);
      al_draw_bitmap(girder,gx-gw/2,gy-gh/2,0);
      al_set_target_bitmap(al_get_backbuffer(display));
  }
  ALLEGRO_BITMAP *getland()
  {
      return land;
  }
  ~Background()
  {
      al_destroy_bitmap(land);
      al_destroy_bitmap(girder);
  }
  34private:
  int gw,gh;
  ALLEGRO_BITMAP *land;
  ALLEGRO_BITMAP *girder;
  38};
  39class Player
  40{
  41public:
  Player(float px,float py)
  {
      x=px;
      y=py;
      gravity=0.125;
      ymove=0;
      player=al_load_bitmap("images/player.png");
      penw=al_get_bitmap_width(player);
      penh=al_get_bitmap_height(player);
      radius=al_get_bitmap_height(player)/2;
  }
  void movepen()
  {
      ymove+=gravity;
      if(ymove>=12)
      {
          ymove=12;
      }
  }
  void collision(ALLEGRO_BITMAP* land)
  {
      //this is the collision
      al_lock_bitmap(land,al_get_bitmap_format(land),ALLEGRO_LOCK_READONLY);
      for(int f=0;f<penh;f++)
      {
          for(int c=0;c<penw;c++)
          {
              color=al_get_pixel(land,x+c,y+f);
              dis=sqrt(pow((penw/2)-c,2)+pow((penh/2)-f,2));
              if(color.a!=0 && dis<=radius)
              {
                  for(int fy=0;fy<=ymove+1;fy++)
                  {
                      color=al_get_pixel(land,x+penw/2,y+penh-fy);
                      if(color.a==0)
                      {
                          y-=fy;
                          fy=ymove+2;
                      }
                  }
                  ymove=0;
              }
          }
      }
      y+=ymove;
  }
  void draw()
  {
      al_draw_bitmap(player,floor(x),floor(y),flip);
  }
  ~Player()
  {
      al_destroy_bitmap(player);
  }
  96private:
  bool flip;
  int penw,penh,radius;
  float x,y,ymove,gravity,dis;
  ALLEGRO_COLOR color;
  ALLEGRO_BITMAP *player;
 102};
 103int main()
 104{
  //inits and creating the window
  Player pen(256,32,display);
  Background drawback();
  drawback.load_map();
  //create stuff such as a timer, events, and variables
  while(!done)
  {
      ALLEGRO_EVENT events;
      al_wait_for_event(event_queue,&events);
      if(events.type==ALLEGRO_EVENT_KEY_UP)
      {
          switch(events.keyboard.keycode)
          {
          case ALLEGRO_KEY_ESCAPE:
              done=true;
              break;
          }
      }
      else if(events.type==ALLEGRO_EVENT_DISPLAY_CLOSE)
      {
          done=true;
      }
      else if (events.type==ALLEGRO_EVENT_MOUSE_AXES)
      {
          mx=events.mouse.x;
          my=events.mouse.y;
      }
      else if (events.type==ALLEGRO_EVENT_MOUSE_BUTTON_DOWN)
      {
          if(events.mouse.button & 1)
          {
              drawback.addgirder(mx,my,display);
          }
      }
      if(events.type==ALLEGRO_EVENT_TIMER)
      {
          pen.movepen();
          draw=true;
      }
      if(draw)
      {
          pen.collision(drawback.getland());
          drawback.drawland();
          pen.draw();
          al_flip_display();
          al_clear_to_color(al_map_rgb(50,50,50));
          draw=false;
      }
  }
  //destroy stuff
  return 0;
 156}

Is there some sort of function to update the bitmap or something or did I just do something wrong.???

no-reply@allegro.cc (Edgar Reynaldo) — Mon, 24 Jun 2013 23:21:41 +0000

Every time you call addgirder you change the target bitmap. You have to change it back to the backbuffer using al_set_target_bitmap(al_get_backbuffer(display));

no-reply@allegro.cc (KirbyDS11) — Mon, 24 Jun 2013 23:38:33 +0000

Edgar Reynaldo said:

You have to change it back to the backbuffer using al_set_target_bitmap(al_get_backbuffer(display));

this code is already in the function addgirder which is on line 18 of the code. Everything gets drawn fine but the pixel information is not picked up by al_get_pixel

no-reply@allegro.cc (Edgar Reynaldo) — Mon, 24 Jun 2013 23:45:31 +0000

Oh sorry I totally missed that. Let me look again. You never unlocked the bitmap. Maybe that's it?

no-reply@allegro.cc (KirbyDS11) — Mon, 24 Jun 2013 23:53:36 +0000

Thank you.
unlocking the bitmap worked.

Drawing to bitmaps and collisions not working