Task: Fractal tree

C: #include <SDL/SDL.h>
#ifdef WITH_CAIRO
#include <cairo.h>
#else
#include <SDL/sge.h>
#endif
#include <cairo.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>

#ifdef WITH_CAIRO
#define PI 3.1415926535
#endif
 
#define SIZE           800   
#define SCALE          5     
#define BRANCHES       14    
#define ROTATION_SCALE 0.75  
#define INITIAL_LENGTH 50    
 
double rand_fl(){
  return (double)rand() / (double)RAND_MAX;
}
 
void draw_tree(SDL_Surface * surface, double offsetx, double offsety,
               double directionx, double directiony, double size,
               double rotation, int depth) {
#ifdef WITH_CAIRO
  cairo_surface_t *surf = cairo_image_surface_create_for_data( surface->pixels,
                                                               CAIRO_FORMAT_RGB24,
							       surface->w, surface->h,
							       surface->pitch );
  cairo_t *ct = cairo_create(surf);

  cairo_set_line_width(ct, 1);
  cairo_set_source_rgba(ct, 0,0,0,1);
  cairo_move_to(ct, (int)offsetx, (int)offsety);
  cairo_line_to(ct, (int)(offsetx + directionx * size), (int)(offsety + directiony * size));
  cairo_stroke(ct);
#else
  sge_AALine(surface,
      (int)offsetx, (int)offsety,
      (int)(offsetx + directionx * size), (int)(offsety + directiony * size),
      SDL_MapRGB(surface->format, 0, 0, 0));
#endif
  if (depth > 0){
    
    draw_tree(surface,
        offsetx + directionx * size,
        offsety + directiony * size,
        directionx * cos(rotation) + directiony * sin(rotation),
        directionx * -sin(rotation) + directiony * cos(rotation),
        size * rand_fl() / SCALE + size * (SCALE - 1) / SCALE,
        rotation * ROTATION_SCALE,
        depth - 1);
 
    
    draw_tree(surface,
        offsetx + directionx * size,
        offsety + directiony * size,
        directionx * cos(-rotation) + directiony * sin(-rotation),
        directionx * -sin(-rotation) + directiony * cos(-rotation),
        size * rand_fl() / SCALE + size * (SCALE - 1) / SCALE,
        rotation * ROTATION_SCALE,
        depth - 1);
  }
}
 
void render(SDL_Surface * surface){
  SDL_FillRect(surface, NULL, SDL_MapRGB(surface->format, 255, 255, 255));
  draw_tree(surface,
      surface->w / 2.0,
      surface->h - 10.0,
      0.0, -1.0,
      INITIAL_LENGTH,
      PI / 8,
      BRANCHES);
  SDL_UpdateRect(surface, 0, 0, 0, 0);
}
 
int main(){
  SDL_Surface * screen;
  SDL_Event evt;
 
  SDL_Init(SDL_INIT_VIDEO);
 
  srand((unsigned)time(NULL));
 
  screen = SDL_SetVideoMode(SIZE, SIZE, 32, SDL_HWSURFACE);
 
  render(screen);
  while(1){
    if (SDL_PollEvent(&evt)){
      if(evt.type == SDL_QUIT) break;
    }
    SDL_Delay(1);
  }
  SDL_Quit();
  return 0;
}











Ada: with Ada.Numerics.Elementary_Functions;

with SDL.Video.Windows.Makers;
with SDL.Video.Renderers.Makers;
with SDL.Video.Rectangles;
with SDL.Events.Events;

procedure Fractal_Tree is

   Width   : constant := 600;
   Height  : constant := 600;
   Level   : constant := 13;
   Length  : constant := 130.0;
   X_Start : constant := 475.0;
   Y_Start : constant := 580.0;
   A_Start : constant := -1.54;
   Angle_1 : constant := 0.10;
   Angle_2 : constant := 0.35;
   C_1     : constant := 0.71;
   C_2     : constant := 0.87;

   Window   : SDL.Video.Windows.Window;
   Renderer : SDL.Video.Renderers.Renderer;
   Event    : SDL.Events.Events.Events;

   procedure Draw_Tree (Level  : in Natural;
                        Length : in Float;
                        Angle  : in Float;
                        X, Y   : in Float)
   is
      use SDL;
      use Ada.Numerics.Elementary_Functions;
      Pi   : constant       := Ada.Numerics.Pi;
      X_2  : constant Float := X + Length * Cos (Angle, 2.0 * Pi);
      Y_2  : constant Float := Y + Length * Sin (Angle, 2.0 * Pi);
      Line : constant SDL.Video.Rectangles.Line_Segment
        := ((C.int (X), C.int (Y)), (C.int (X_2), C.int (Y_2)));
   begin
      if Level > 0 then
         Renderer.Set_Draw_Colour (Colour => (0, 220, 0, 255));
         Renderer.Draw (Line => Line);

         Draw_Tree (Level - 1, C_1 * Length, Angle + Angle_1, X_2, Y_2);
         Draw_Tree (Level - 1, C_2 * Length, Angle - Angle_2, X_2, Y_2);
      end if;
   end Draw_Tree;

   procedure Wait is
      use type SDL.Events.Event_Types;
   begin
      loop
         while SDL.Events.Events.Poll (Event) loop
            if Event.Common.Event_Type = SDL.Events.Quit then
               return;
            end if;
         end loop;
         delay 0.100;
      end loop;
   end Wait;

begin
   if not SDL.Initialise (Flags => SDL.Enable_Screen) then
      return;
   end if;

   SDL.Video.Windows.Makers.Create (Win      => Window,
                                    Title    => "Fractal tree",
                                    Position => SDL.Natural_Coordinates'(X => 10, Y => 10),
                                    Size     => SDL.Positive_Sizes'(Width, Height),
                                    Flags    => 0);
   SDL.Video.Renderers.Makers.Create (Renderer, Window.Get_Surface);
   Renderer.Set_Draw_Colour ((0, 0, 0, 255));
   Renderer.Fill (Rectangle => (0, 0, Width, Height));

   Draw_Tree (Level, Length, A_Start, X_Start, Y_Start);
   Window.Update_Surface;

   Wait;
   Window.Finalize;
   SDL.Finalise;
end Fractal_Tree;