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with
Ada.Numerics.Generic_Complex_Types,
Ada.Containers.Vectors,
Ada.Characters.Latin_1,
Ada.Text_IO;
procedure Fluid_Simulator is
package Latin renames Ada.Characters.Latin_1;
package IO renames Ada.Text_IO;
procedure Clear_Screen is
begin
-- ANSI control sequence Erase in Display
-- Variant to clear entire screen
IO.Put (Latin.ESC & "[2J");
end Clear_Screen;
procedure Reset_Cursor is
begin
-- ANSI control sequence Cursor Position
-- Parameters to move cursor to top left corner
IO.Put (Latin.ESC & "[1;1H");
end Reset_Cursor;
type Quantity is digits 18;
package Fixed is new Ada.Numerics.Generic_Complex_Types (Real => Quantity);
use type Fixed.Complex;
type Particle is record
Place : Fixed.Complex;
Solid : Boolean;
Density : Quantity := 0.0;
Acceleration : Fixed.Complex := Fixed.Compose_From_Cartesian (0.0, 0.0);
Velocity : Fixed.Complex := Fixed.Compose_From_Cartesian (0.0, 0.0);
end record;
function Create
(X, Y : Quantity;
Solid : in Boolean)
return Particle is
begin
return (Place => Fixed.Compose_From_Cartesian (X, Y), Solid => Solid, others => <>);
end Create;
-- Constant properties of particles
Particle_Radius : constant Quantity := 2.0;
Particle_Mass : constant Quantity := 1.0;
-- Constant used in calculating fluid interaction forces
P0 : constant Quantity := 1.5;
-- Other constant force factors
Gravity_Factor : constant Fixed.Complex := Fixed.Compose_From_Cartesian (0.0, 1.0);
Pressure_Factor : constant Quantity := 4.0;
Viscosity_Factor : constant Quantity := 8.0;
package Particle_Vectors is new Ada.Containers.Vectors
(Index_Type => Positive,
Element_Type => Particle);
Particles : Particle_Vectors.Vector := Particle_Vectors.Empty_Vector;
procedure Read_Input
(Store : out Particle_Vectors.Vector)
is
Input : Character;
X, Y : Quantity := 1.0;
begin
while not IO.End_Of_File (IO.Standard_Input) loop
IO.Get_Immediate (Input);
if Input = Latin.LF then
X := 1.0;
Y := Y + 1.0;
else
if Input > Latin.Space and Input < Latin.DEL then
Store.Append (Create (X, Y, (Input = '#')));
end if;
X := X + 1.0;
end if;
end loop;
end Read_Input;
function Marching_Squares
(Input : in Particle_Vectors.Vector)
return String
is
Liquid_Chars : String (1 .. 16) := " .,_`/[/']\\-/\#";
Grid : array (0 .. 80, 0 .. 25) of Boolean := (others => (others => False));
Output : String (1 .. 2025);
X, Y : Integer;
begin
for P of Input loop
X := Integer (Fixed.Re (P.Place));
Y := Integer (Fixed.Im (P.Place));
if X >= 0 and X <= 80 and Y >= 0 and Y <= 25 then
Grid (X, Y) := True;
end if;
end loop;
for J in Integer range 1 .. 25 loop
for I in Integer range 1 .. 80 loop
Output ((J - 1) * 81 + I) := Liquid_Chars
(Boolean'Pos (Grid (I - 1, J)) + 1 +
Boolean'Pos (Grid (I, J)) * 2 +
Boolean'Pos (Grid (I, J - 1)) * 4 +
Boolean'Pos (Grid (I - 1, J - 1)) * 8);
end loop;
Output (J * 81) := Latin.LF;
end loop;
return Output;
end Marching_Squares;
procedure Calculate_Density
(Store : in out Particle_Vectors.Vector)
is
Rij, W : Quantity;
begin
for P of Store loop
P.Density := (if P.Solid then 9.0 else 0.0);
for Q of Store loop
Rij := Fixed.Modulus (P.Place - Q.Place);
W := (Rij / Particle_Radius - 1.0) ** 2;
if Rij < Particle_Radius then
P.Density := P.Density + Particle_Mass * W;
end if;
end loop;
end loop;
end Calculate_Density;
procedure Calculate_Interaction
(Store : in out Particle_Vectors.Vector)
is
Displacement, Pressure, Viscosity : Fixed.Complex;
Rij : Quantity;
begin
for P of Store loop
P.Acceleration := Gravity_Factor;
for Q of Store loop
Displacement := P.Place - Q.Place;
Rij := Fixed.Modulus (Displacement);
if Rij < Particle_Radius then
Pressure := (P.Density + Q.Density - 2.0 * P0) * Pressure_Factor * Displacement;
Viscosity := (P.Velocity - Q.Velocity) * Viscosity_Factor;
P.Acceleration := P.Acceleration +
Fixed.Compose_From_Cartesian (1.0 - Rij / Particle_Radius) /
P.Density * (Pressure - Viscosity);
end if;
end loop;
end loop;
end Calculate_Interaction;
procedure Update_Position
(Store : in out Particle_Vectors.Vector) is
begin
for P of Store loop
if not P.Solid then
P.Velocity := P.Velocity + P.Acceleration / 10.0;
P.Place := P.Place + P.Velocity;
end if;
end loop;
end Update_Position;
procedure Cull_Outside_Bounds
(Store : in out Particle_Vectors.Vector;
Threshold : in Quantity) is
begin
for C in reverse Store.First_Index .. Store.Last_Index loop
if Fixed.Re (Store (C).Place) < 0.0 - Threshold or
Fixed.Re (Store (C).Place) > 80.0 + Threshold or
Fixed.Im (Store (C).Place) < 0.0 - Threshold or
Fixed.Im (Store (C).Place) > 25.0 + Threshold
then
Store.Delete (C);
end if;
end loop;
end Cull_Outside_Bounds;
begin
Read_Input (Particles);
loop
Clear_Screen;
Reset_Cursor;
IO.Put (Marching_Squares (Particles));
Calculate_Density (Particles);
Calculate_Interaction (Particles);
Update_Position (Particles);
Cull_Outside_Bounds (Particles, 50.0);
delay 0.012321;
end loop;
end Fluid_Simulator;
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