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| unit UMain;
interface
uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, ExtCtrls, dglopengl, glBitmap, F2D_Core;
const N = 128; size = (N+2)*(N+2);
type TSingleArray = array [1..size-1] of Single;
var u, v, u_prev, v_prev, dens, dens_prev: TSingleArray; visc, diff, dt: single; force, source: single;
type TMainForm = class(TForm) procedure FormMouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer); procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer); procedure FormMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer); procedure FormKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState); procedure FormDestroy(Sender: TObject); procedure FormCreate(Sender: TObject); procedure ApplicationEventsIdle(Sender: TObject; var Done: Boolean); procedure getstates(d, u, v: TSingleArray); private CalcTime, Frequency: int64; public Engine: TEngine; end;
var MainForm: TMainForm; veldenstoggle: boolean; omx, omy, mx, my: integer; mouse1, mouse2: boolean;
implementation
{$R *.dfm}
function IX(i, j: integer): integer; begin result := ((i)+(N+2)*(j)); end;
procedure SWAP(x0, x: TSingleArray); var tmp: TSingleArray; begin tmp := x0; x0 := x; x := tmp; end;
procedure set_bnd(N, b: integer; x: TSingleArray); var i: integer; begin for i := 1 to N do begin if b = 1 then begin x[IX(0, i)] := -x[IX(1, i)]; x[IX(N+1,i)] := -x[IX(N, i)]; end else begin x[IX(0, i)] := x[IX(1, i)]; x[IX(N+1,i)] := x[IX(N, i)]; end; if b = 2 then begin x[IX(i, 0)] := -x[IX(i, 1)]; x[IX(i, N+1)] := -x[IX(i, N)]; end else begin x[IX(i, 0)] := x[IX(i,1 )]; x[IX(i, N+1)] := x[IX(i, N)]; end; end; x[IX(0, 0)] := 0.5*(x[IX(1, 0)]+x[IX(0, 1)]); x[IX(0, N+1)] := 0.5*(x[IX(1,N+1)]+x[IX(0 ,N)]); x[IX(N+1, 0)] := 0.5*(x[IX(N, 0)]+x[IX(N+1, 1)]); x[IX(N+1, N+1)] := 0.5*(x[IX(N, N+1)]+x[IX(N+1, N)]); end;
procedure project(N: integer; u, v, p, divi: TSingleArray); var i, j, k: integer; h: single; begin h := 1/N; for i := 1 to N do for j := 1 to N do begin divi[IX(i, j)] := -0.5*h*(u[IX(i+1, j)]-u[IX(i-1, j)]+v[IX(i, j+1)]-v[IX(i, j-1)]); p[IX(i, j)] := 0; end; set_bnd(N, 0, divi); set_bnd(N, 0, p); for k := 0 to 19 do for i := 1 to N do for j := 1 to N do p[IX(i, j)] := (divi[IX(i, j)]+p[IX(i-1, j)]+p[IX(i+1, j)]+p[IX(i, j-1)]+p[IX(i, j+1)])/4; set_bnd(N, 0, p); for i := 1 to N do for j := 1 to N do begin u[IX(i, j)] := u[IX(i, j)] - (0.5*(p[IX(i+1, j)]-p[IX(i-1, j)])/h); v[IX(i, j)] := v[IX(i, j)] - (0.5*(p[IX(i, j+1)]-p[IX(i, j-1)])/h) end; set_bnd(N, 1, u); set_bnd(N, 2, v); end;
procedure add_source(N: integer; x, s: TSingleArray; dt: single); var i: integer; begin for i := 1 to size-1 do x[i] := x[i]+dt*s[i]; end;
procedure diffuse(N, b: integer; x, x0: TSingleArray; diff, dt: single); var i, j, k: integer; a: single; begin a := dt*diff*N*N; for k := 0 to 19 do for i := 1 to N do for j := 1 to N do x[IX(i, j)] := (x0[IX(i, j)] + a*(x[IX(i-1, j)]+x[IX(i+1, j)] + x[IX(i, j-1)] + x[IX(i, j+1)])) / (1+4*a); set_bnd(N, b, x); end;
procedure advect(N, b: integer; d, d0, u, v: TSingleArray; dt: single); var i, j, i0, j0, i1, j1: integer; x, y, s0, t0, s1, t1, dt0: single; begin dt0 := dt*N; for i := 1 to N do for j := 1 to N do begin x := i-dt0*u[IX(i, j)]; y := j-dt0*v[IX(i, j)]; if (x < 0.5) then x := 0.5; if (x > N + 0.5) then x := N + 0.5; i0 := round(x); i1 := i0 + 1; if (y < 0.5) then y := 0.5; if (y > N + 0.5) then y := N + 0.5; j0 := round(y); j1 := j0 + 1; s1 := x-i0; s0 := 1-s1; t1 := y-j0; t0 := 1-t1; d[IX(i, j)] := s0*(t0*d0[IX(i0, j0)]+t1*d0[IX(i0, j1)])+s1*(t0*d0[IX(i1, j0)]+t1*d0[IX(i1, j1)]); end; set_bnd(N, b, d); end;
procedure dens_step(N: integer; x, x0, u, v: TSingleArray; diff, dt: single); begin add_source(N, x, x0, dt); SWAP(x0, x); diffuse(N, 0, x, x0, diff, dt); SWAP(x0, x); advect(N, 0, x, x0, u, v, dt); end;
procedure vel_step(N: integer; u, v, u0, v0: TSingleArray; visc, dt: single); begin add_source(N, u, u0, dt); add_source(N, v, v0, dt); SWAP(u0, u); diffuse(N, 1, u, u0, visc, dt); SWAP(v0, v); diffuse(N, 2, v, v0, visc, dt); project(N, u, v, u0, v0); SWAP(u0, u); SWAP(v0, v); advect(N, 1, u, u0, u0, v0, dt); advect(N, 2, v, v0, u0, v0, dt); project(N, u, v, u0, v0); end;
procedure draw_velocity; var i, j: integer; x, y, h: single; begin h := 1 / N;
glColor3f(1, 1, 1); glLineWidth(1);
glBegin(GL_LINES); for i := 1 to N do begin x := (i - 0.5) * h; for j := 1 to N do begin y := (j - 0.5) * h; glVertex2f(x, y); glVertex2f(x + u[IX(i, j)], y + v[IX(i, j)]); end end; glEnd; end;
procedure draw_density; var i, j: integer; x, y, h, d00, d01, d10, d11: single; begin h := 1 / N; glBegin(GL_QUADS); for i := 0 to N do begin x := (i - 0.5) *h; for j := 0 to N do begin y := (j - 0.5) *h; d00 := dens[IX(i, j)]; d01 := dens[IX(i, j + 1)]; d10 := dens[IX(i + 1, j)]; d11 := dens[IX(i + 1, j + 1)];
glColor3f(d00, d00, d00); glVertex2f(x, y); glColor3f(d10, d10, d10); glVertex2f(x + h, y); glColor3f(d11, d11, d11); glVertex2f(x + h, y + h); glColor3f(d01, d01, d01); glVertex2f(x, y + h); end; end; glEnd; end;
procedure ResetSimulation; const size = (N + 2) * (N + 2); var i: integer; begin for i := 0 to size - 1 do begin u[i] := 0; v[i] := 0; u_prev[i] := 0; v_prev[i] := 0; dens[i] := 0; dens_prev[i] := 0; end; end;
procedure TMainForm.FormCreate(Sender: TObject); begin diff := 0; visc := 0; force := 5; source := 100;
mouse1 := false; mouse2 := false;
veldenstoggle := true;
Engine := TEngine.Create(false); Engine.Init(self); Application.OnIdle := ApplicationEventsIdle; end;
procedure TMainForm.FormDestroy(Sender: TObject); begin Engine.Free; end;
procedure TMainForm.getstates(d, u, v: TSingleArray); const size = (N + 2) * (N + 2); var i, j: integer; begin for i := 0 to size - 1 do begin u[i] := 0; v[i] := 0; d[i] := 0; end;
if (not mouse1) and (not mouse2) then exit;
i := round((mx / Engine.width) * N + 1); j := round(((Engine.Height - my) / Engine.Height) * N + 1);
if (i < 1) or (i > N) or (j < 1) or (j > N) then exit;
if mouse1 then begin u[IX(i, j)] := force * (mx - omx); v[IX(i, j)] := force * (omy - my); end;
if mouse2 then d[IX(i, j)] := source;
omx := mx; omy := my; end;
procedure TMainForm.ApplicationEventsIdle(Sender: TObject; var Done: Boolean); begin Engine.DoBegin;
dt := Engine.Timestep;
getstates(dens_prev, u_prev, v_prev);
vel_step(N, u, v, u_prev, v_prev, visc, dt); dens_step(N, dens, dens_prev, u, v, diff, dt);
if veldenstoggle = true then draw_velocity else draw_density;
MainForm.Caption := 'FPS: ' + floattostr(Engine.FPS);
Engine.DoEnd; done := false; end;
procedure TMainForm.FormKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState); begin if key = ord('v') then veldenstoggle := not veldenstoggle; if key = ord('c') then ResetSimulation; end;
procedure TMainForm.FormMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer); begin if ssleft in shift then mouse1 := true; if ssright in shift then mouse2 := true; omx := x; omx := y; mx := x; my := y; end;
procedure TMainForm.FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer); begin mx := x; my := y; end;
procedure TMainForm.FormMouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer); begin if ssleft in shift then mouse1 := false; if ssright in shift then mouse2 := false; end;
Initialization randomize;
end. |