发信人: rhine (有雨无风), 信区: BorlandDev
标  题: OpenGL在C++Builder中的应用(2)
发信站: 哈工大紫丁香 (Sun Aug 27 06:38:01 2000), 转信

发信人: jinchao (Sonic), 信区: BCB
发信站: BBS 水木清华站 (Fri Jul 30 08:58:52 1999) WWW-POST

                           (二)第一个OpenGL程序
    记得以前学习编程时，每学一门新语言，我总先按书上编一个最简单的例子上机通过
，然后再开始学习它的语法，这样有利于感性的培养。这里我也先给出一个最简单OpenGL
程序，它只是在窗口上画出一个矩形，如果你能调试出正确结果，那恭喜你迈出第一步。

    (1). 选择File->New Application,新建一个程序，把它保存到一目录下
    (2). 打开主窗体头文件Unit1.h，修改如下：
//---------------------------------------------------------------------------

#ifndef Unit1H
#define Unit1H
//---------------------------------------------------------------------------

#include <Classes.hpp>
#include <Controls.hpp>
#include <StdCtrls.hpp>
#include <Forms.hpp>
#include <gl\gl.h>              /*记得加上这两行*/
#include <gl\glu.h>
//---------------------------------------------------------------------------

class TForm1 : public TForm
{
__published:    // IDE-managed Components
private:        // User declarations
    HGLRC hRC;                  /* 新加的两个成员 */
    void DrawWithOpenGL();
public:         // User declarations
    __fastcall TForm1(TComponent* Owner);
};
//---------------------------------------------------------------------------

extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------

#endif

   (3). 打开主窗体文件Unit1.cpp修改如下
//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop
#include "Unit1.h"
//---------------------------------------------------------------------------

#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------

__fastcall TForm1::TForm1(TComponent* Owner)
    : TForm(Owner)
{
}
//---------------------------------------------------------------------------

void TForm1::DrawWithOpenGL()
{
    HDC hDC;
    glClearColor(0.0f,0.0f,0.0f,1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    glBegin(GL_QUADS);
      glColor3f(1.0f,1.0f,1.0f);glVertex3f(1.0f,1.0f,0.0f);
      glColor3f(1.0f,0.0f,0.0f);glVertex3f(3.0f,1.0f,0.0f);
      glColor3f(0.0f,1.0f,0.0f);glVertex3f(3.0f,3.0f,0.0f);
      glColor3f(0.0f,0.0f,1.0f);glVertex3f(1.0f,3.0f,0.0f);
    glEnd();

    glFlush();
    hDC = wglGetCurrentDC();
    SwapBuffers(hDC);
}
//------------- 对应窗体的OnResize事件，下面几个函数类同-------
void __fastcall TForm1::FormResize(TObject *Sender)  
{
    HDC hDC;
    hDC=GetDC(this->Handle);
    wglMakeCurrent(hDC,hRC);
    glViewport(0,0,this->ClientWidth,this->ClientHeight);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    glOrtho(0.0f,4.0f,0.0f,4.0f,0.0f,4.0f);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    wglMakeCurrent(NULL,NULL);
    ReleaseDC(this->Handle,hDC);
}
//---------------------------------------------------------------------------

void __fastcall TForm1::FormDestroy(TObject *Sender)
{
    wglDeleteContext(hRC);
}
//---------------------------------------------------------------------------

void __fastcall TForm1::FormCreate(TObject *Sender)
{
    PIXELFORMATDESCRIPTOR pfd =
      {
            sizeof(PIXELFORMATDESCRIPTOR),
            1,
            PFD_DRAW_TO_WINDOW|
            PFD_SUPPORT_OPENGL|
            PFD_DOUBLEBUFFER,
            PFD_TYPE_RGBA,
            24,
            0,0,0,0,0,0,
            0,0,0,0,0,0,0,
            32,
            0,0,
            PFD_MAIN_PLANE,
            0,
            0,0,0
     };
    HDC hDC=GetDC(this->Handle);
    int pixelFormat;
    if((pixelFormat=ChoosePixelFormat(hDC,&pfd))==0)
      {
         MessageBox(NULL,"ChoosePixelFormat Error!","Error",MB_OK);
         return;
      }
    if(SetPixelFormat(hDC,pixelFormat,&pfd)==false)
      {
        MessageBox(NULL,"SetPixelFormat Error!","Error",MB_OK);
        return ;
      }
    hRC=wglCreateContext(hDC);  
    glClearColor(0.0f,0.0f,0.0f,0.0f);
    glClear(GL_COLOR_BUFFER_BIT);
    glShadeModel(GL_SMOOTH);
    ReleaseDC(this->Handle,hDC);
}
//---------------------------------------------------------------------------

void __fastcall TForm1::FormPaint(TObject *Sender)
{
    HDC hDC=GetDC(this->Handle);
    wglMakeCurrent(hDC,hRC);

        DrawWithOpenGL();

    wglMakeCurrent(hDC,NULL);
    ReleaseDC(this->Handle,hDC);
}
//---------------------------------------------------------------------------

    (4). 现在可以编译通过，注意系统起码要在16bits真彩模式下，看到矩形内部的色
彩过度了吗，这是OpenGL良好的插值运算的结果，是不是有些心动了呢？

--
        念天地之悠悠,
        独沧然而泪下,
        知我者谓我心忧，
        不知我者谓我何求......

--
☆ 来源:．哈工大紫丁香 bbs.hit.edu.cn．[FROM: rhine.bbs@smth.org]