delphi - OpenGL在屏幕上看不到雾

Question

我开始学习opengl，在了解了light之后开始阅读fog，但是当我尝试将fog输入到程序中时却没有看到。问题是什么？

PS这里是代码：

unit MainUnit;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes,         Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs,dglOpenGL,dglut;

type
  TFMainForm = class(TForm)

procedure FormCreate(Sender: TObject);
procedure FormResize(Sender: TObject);
procedure FormDestroy(Sender: TObject);
private

procedure SetupGL;
procedure uzglLightEnable;
procedure IdleHandler(Sender : TObject; var Done : Boolean);

public

procedure Render;

end;

var
  FMainForm: TFMainForm;
  dc:hdc;
  hrc:hglrc;
  XRot,YRot,ZRot:Single;
  XPos,ZPos:single;

  LightPos:TGLArrayf4=(0,0,1,1);
  BlueArray:TGLArrayf4;
  GreenArray:TGLArrayf4=(0,1,0,0);
  FogStart:TGLArrayf4=(0,0,-5,0);
  FogEnd:  TGLArrayf4=(0,0,5,0);
  myTex: glUint;

  FrontNormal: TGLvectorf3=(0,0,1);
  BackNormal: TGLvectorf3 =(0,0,-1);
  LeftNormal: TGLvectorf3 =(1,0,0);
  RightNormal: TGLvectorf3=(-1,0,0);
  UpNormal: TGLvectorf3   =(0,-1,0);
  DownNormal: TGLvectorf3 =(0,1,0);

  FrontDownLeft :TGLvectorf3 = (-1,-1,-1);
  FrontDownRight:TGLvectorf3 = (1,-1,-1);
  FrontUpLeft   :TGLvectorf3 = (-1,1,-1);
  FrontUpRight  :TGLvectorf3 = (1,1,-1);

  BackDownLeft :TGLvectorf3 = (-1,-1,1);
  BackDownRight:TGLvectorf3 = (1,-1,1);
  BackUpLeft   :TGLvectorf3 = (-1,1,1);
  BackUpRight  :TGLvectorf3 = (1,1,1);


const
  NearClipping = 0.1;
  FarClipping  = 200;

  procedure uzglTriangle(x1,y1,z1,x2,y2,z2,x3,y3,z3:single);

  procedure uzglCube;

implementation

{$R *.dfm}



procedure uzglTriangle(x1,y1,z1,x2,y2,z2,x3,y3,z3:single);
begin
glBegin(GL_TRIANGLES);
glColor3f(0.3,0,0);glVertex3f(x1,y1,z1);
glColor3f(0.25,1,0);glVertex3f(x2,y2,z2);
glColor3f(0.7,0,1);glVertex3f(x3,y3,z3);
glEnd;

end;

procedure uzglCube;
begin
glBegin(GL_QUADS);
// Beginning of front
glNormal3fv(@FrontNormal);
glColor3f(1,0,0);glVertex3fv(@FrontDownLeft);
glColor3f(0,1,0);glVertex3fv(@FrontDownRight);
glColor3f(0,0,1);glVertex3fv(@FrontUpRight);
glColor3f(0.686,0.847,1);glVertex3fv(@FrontUpLeft);
// End of front
glEnd;


 glBegin(GL_QUADS);
// Beginning of left
glNormal3fv(@LeftNormal);
glColor3f(1,0,0);glVertex3fv(@FrontDownLeft);
glColor3f(0,1,0);glVertex3fv(@FrontUpLeft);
glColor3f(0,0,1);glVertex3fv(@BackUpLeft);
glColor3f(0.686,0.847,1);glVertex3fv(@BackDownLeft);
// End of left
glEnd;

glBegin(GL_QUADS);
// Beginning of right
glNormal3fv(@RightNormal);
glColor3f(1,0,0);glVertex3fv(@FrontDownRight);
glColor3f(0,1,0);glVertex3fv(@FrontUpRight);
glColor3f(0,0,1);glVertex3fv(@BackUpRight);
glColor3f(0.686,0.847,1);glVertex3fv(@BackDownRight);
// End of right
glEnd;

glBegin(GL_QUADS);
// Beginning of up
glNormal3fv(@UpNormal);
glColor3f(1,0,0);glVertex3fv(@FrontUpRight);
glColor3f(0,1,0);glVertex3fv(@FrontUpLeft);
glColor3f(0,0,1);glVertex3fv(@BackUpLeft);
glColor3f(0.686,0.847,1);glVertex3fv(@BackUpRight);
// End of up
glEnd;

glBegin(GL_QUADS);
// Beginning of down
glNormal3fv(@DownNormal);
glColor3f(1,0,0);glVertex3fv(@FrontDownRight);
glColor3f(0,1,0);glVertex3fv(@FrontDownLeft);
glColor3f(0,0,1);glVertex3fv(@BackDownLeft);
glColor3f(0.686,0.847,1);glVertex3fv(@BackDownRight);
// End of down
glEnd;

glBegin(GL_QUADS);
// Beginning of back
glNormal3fv(@BackNormal);
glColor3f(1,0,0);glVertex3fv(@BackDownLeft);
glColor3f(0,1,0);glVertex3fv(@BackDownRight);
glColor3f(0,0,1);glVertex3fv(@BackUpRight);
glColor3f(0.686,0.847,1);glVertex3fv(@BackUpLeft);
// End of back
glEnd;



end;
procedure TFMainForm.SetupGL;
begin
  glClearColor(0.3,0.4,0.7,0.0);
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_SMOOTH);
  glDepthFunc(GL_LEQUAL);
  glEnable(GL_TEXTURE_2D);
  uzglLightEnable;
  glEnable(GL_FOG);
  glFogi(GL_FOG_MODE, GL_LINEAR);
  glFogf(GL_FOG_START,1);
  glFogf(Gl_FOG_END,50);
  glFogfv(GL_FOG_COLOR, @GreenArray);
  glFogF(GL_FOG_DENSITY,1);

  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity;
  gluLookAt(-2, 3, -4, 0,0,0, 0,1,0);


end;

procedure TFMainForm.uzglLightEnable;

begin
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_COLOR_MATERIAL);
end;
///////////////////////////////////////////////////////////////
procedure TFMainForm.Render;
var i:integer;
begin
  glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);

  glMatrixMode(GL_MODELVIEW);
  glPushMatrix;
  glRotatef(XRot,1,0.5,0.5);
  uzglCube;
  glPopMatrix;

  glLightfv(GL_LIGHT0, GL_POSITION, @LightPos);

  SwapBuffers(dc);

  XRot:=XRot+1;
end;
////////////////////////////////////////////////////////////////

procedure TFMainForm.IdleHandler(Sender : TObject; var Done : Boolean);
begin
Render;
Sleep(25);
Done:=false;
end;

procedure TFMainForm.FormCreate(Sender: TObject);
begin
dc:=GetDC(Handle);

if not InitOpenGL then
                  begin
                  ShowMessage('Печалька... Инициализация провалилась');
                  Application.Terminate;
                  end;

hrc:=CreateRenderingContext       (dc,
                                   [opDoubleBuffered],
                                   32,
                                   24,
                                   8,
                                   0,
                                   0,
                                   0);

ActivateRenderingContext(dc,hrc);
SetupGL;
Application.OnIdle:=IdleHandler;
FMainForm.OnResize(self);
end;



procedure TFMainForm.FormResize(Sender: TObject);
var tmpBool:boolean;
begin
glViewport(0,0,ClientWidth,ClientHeight);
glMatrixMode(GL_PROJECTION);
glLoadIdentity;
gluPerspective(45.0,ClientWidth/ClientHeight,NearClipping,FarClipping);

idleHandler(Sender, tmpBool);
end;


procedure TFMainForm.FormDestroy(Sender: TObject);
begin
DeactivateRenderingContext;
DestroyRenderingContext(hrc);
ReleaseDC(Handle,dc);
end;


end.

Answer 1

在SetupGL程序变化

glFogf(Gl_FOG_END,50);

至

glFogf(Gl_FOG_END, 7);

这对我有用。