lesson9.cpp

关于OpenGL的实例教程源代码

/*
 *		This Code Was Created By Jeff Molofee 2000
 *		A HUGE Thanks To Fredric Echols For Cleaning Up
 *		And Optimizing The Base Code, Making It More Flexible!
 *		If You've Found This Code Useful, Please Let Me Know.
 *		Visit My Site At nehe.gamedev.net
 */

#include <windows.h>		// Header File For Windows
#include <stdio.h>			// Header File For Standard Input/Output
#include <gl\gl.h>			// Header File For The OpenGL32 Library
#include <gl\glu.h>			// Header File For The GLu32 Library
#include <gl\glaux.h>		// Header File For The Glaux Library

HDC			hDC=NULL;		// Private GDI Device Context
HGLRC		hRC=NULL;		// Permanent Rendering Context
HWND		hWnd=NULL;		// Holds Our Window Handle
HINSTANCE	hInstance;		// Holds The Instance Of The Application

bool	keys[256];			// Array Used For The Keyboard Routine
bool	active=TRUE;		// Window Active Flag Set To TRUE By Default
bool	fullscreen=TRUE;	// Fullscreen Flag Set To Fullscreen Mode By Default

bool	twinkle;			// Twinkling Stars
bool	tp;					// 'T' Key Pressed?

const	num=50;				// Number Of Stars To Draw

typedef struct				// Create A Structure For Star
{
	int r, g, b;			// Stars Color
	GLfloat dist,			// Stars Distance From Center
			angle;			// Stars Current Angle
}
stars;
stars star[num];			// Need To Keep Track Of 'num' Stars

GLfloat	zoom=-15.0f;		// Distance Away From Stars
GLfloat tilt=90.0f;			// Tilt The View
GLfloat	spin;				// Spin Stars

GLuint	loop;				// General Loop Variable
GLuint	texture[1];			// Storage For One textures

LRESULT	CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);	// Declaration For WndProc

AUX_RGBImageRec *LoadBMP(char *Filename)                // Loads A Bitmap Image
{
        FILE *File=NULL;                                // File Handle

        if (!Filename)                                  // Make Sure A Filename Was Given
        {
                return NULL;                            // If Not Return NULL
        }

        File=fopen(Filename,"r");                       // Check To See If The File Exists

        if (File)                                       // Does The File Exist?
        {
                fclose(File);                           // Close The Handle
                return auxDIBImageLoad(Filename);       // Load The Bitmap And Return A Pointer
        }
        return NULL;                                    // If Load Failed Return NULL
}

int LoadGLTextures()                                    // Load Bitmaps And Convert To Textures
{
        int Status=FALSE;                               // Status Indicator

        AUX_RGBImageRec *TextureImage[1];               // Create Storage Space For The Texture

        memset(TextureImage,0,sizeof(void *)*1);        // Set The Pointer To NULL

        // Load The Bitmap, Check For Errors, If Bitmap's Not Found Quit
        if (TextureImage[0]=LoadBMP("Data/Star.bmp"))
        {
                Status=TRUE;                            // Set The Status To TRUE

                glGenTextures(1, &texture[0]);          // Create One Texture

                // Create Linear Filtered Texture
                glBindTexture(GL_TEXTURE_2D, texture[0]);
                glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
                glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
                glTexImage2D(GL_TEXTURE_2D, 0, 3, TextureImage[0]->sizeX, TextureImage[0]->sizeY, 0, GL_RGB, GL_UNSIGNED_BYTE, TextureImage[0]->data);
        }
        if (TextureImage[0])                            // If Texture Exists
        {
                if (TextureImage[0]->data)              // If Texture Image Exists
                {
                        free(TextureImage[0]->data);    // Free The Texture Image Memory
                }

                free(TextureImage[0]);                  // Free The Image Structure
        }

        return Status;                                  // Return The Status
}

GLvoid ReSizeGLScene(GLsizei width, GLsizei height)		// Resize And Initialize The GL Window
{
	if (height==0)										// Prevent A Divide By Zero By
	{
		height=1;										// Making Height Equal One
	}

	glViewport(0,0,width,height);						// Reset The Current Viewport

	glMatrixMode(GL_PROJECTION);						// Select The Projection Matrix
	glLoadIdentity();									// Reset The Projection Matrix

	// Calculate The Aspect Ratio Of The Window
	gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);

	glMatrixMode(GL_MODELVIEW);							// Select The Modelview Matrix
	glLoadIdentity();									// Reset The Modelview Matrix
}

int InitGL(GLvoid)										// All Setup For OpenGL Goes Here
{
	if (!LoadGLTextures())								// Jump To Texture Loading Routine
	{
		return FALSE;									// If Texture Didn't Load Return FALSE
	}

	glEnable(GL_TEXTURE_2D);							// Enable Texture Mapping
	glShadeModel(GL_SMOOTH);							// Enable Smooth Shading
	glClearColor(0.0f, 0.0f, 0.0f, 0.5f);				// Black Background
	glClearDepth(1.0f);									// Depth Buffer Setup
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);	// Really Nice Perspective Calculations
	glBlendFunc(GL_SRC_ALPHA,GL_ONE);					// Set The Blending Function For Translucency
	glEnable(GL_BLEND);

	for (loop=0; loop<num; loop++)
	{
		star[loop].angle=0.0f;
		star[loop].dist=(float(loop)/num)*5.0f;
		star[loop].r=rand()%256;
		star[loop].g=rand()%256;
		star[loop].b=rand()%256;
	}
	return TRUE;										// Initialization Went OK
}

int DrawGLScene(GLvoid)									// Here's Where We Do All The Drawing
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);	// Clear The Screen And The Depth Buffer
	glBindTexture(GL_TEXTURE_2D, texture[0]);			// Select Our Texture

	for (loop=0; loop<num; loop++)						// Loop Through All The Stars
	{
		glLoadIdentity();								// Reset The View Before We Draw Each Star
		glTranslatef(0.0f,0.0f,zoom);					// Zoom Into The Screen (Using The Value In 'zoom')
		glRotatef(tilt,1.0f,0.0f,0.0f);					// Tilt The View (Using The Value In 'tilt')
		glRotatef(star[loop].angle,0.0f,1.0f,0.0f);		// Rotate To The Current Stars Angle
		glTranslatef(star[loop].dist,0.0f,0.0f);		// Move Forward On The X Plane
		glRotatef(-star[loop].angle,0.0f,1.0f,0.0f);	// Cancel The Current Stars Angle
		glRotatef(-tilt,1.0f,0.0f,0.0f);				// Cancel The Screen Tilt
		
		if (twinkle)
		{
			glColor4ub(star[(num-loop)-1].r,star[(num-loop)-1].g,star[(num-loop)-1].b,255);
			glBegin(GL_QUADS);
				glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,-1.0f, 0.0f);
				glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,-1.0f, 0.0f);
				glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 0.0f);
				glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 0.0f);
			glEnd();
		}

		glRotatef(spin,0.0f,0.0f,1.0f);
		glColor4ub(star[loop].r,star[loop].g,star[loop].b,255);
		glBegin(GL_QUADS);
			glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,-1.0f, 0.0f);
			glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,-1.0f, 0.0f);
			glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 0.0f);
			glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 0.0f);
		glEnd();

		spin+=0.01f;
		star[loop].angle+=float(loop)/num;
		star[loop].dist-=0.01f;
		if (star[loop].dist<0.0f)
		{
			star[loop].dist+=5.0f;
			star[loop].r=rand()%256;
			star[loop].g=rand()%256;
			star[loop].b=rand()%256;
		}
	}
	return TRUE;										// Everything Went OK
}

GLvoid KillGLWindow(GLvoid)								// Properly Kill The Window
{
	if (fullscreen)										// Are We In Fullscreen Mode?
	{
		ChangeDisplaySettings(NULL,0);					// If So Switch Back To The Desktop
		ShowCursor(TRUE);								// Show Mouse Pointer
	}

	if (hRC)											// Do We Have A Rendering Context?
	{
		if (!wglMakeCurrent(NULL,NULL))					// Are We Able To Release The DC And RC Contexts?
		{
			MessageBox(NULL,"Release Of DC And RC Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		}

		if (!wglDeleteContext(hRC))						// Are We Able To Delete The RC?
		{
			MessageBox(NULL,"Release Rendering Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		}
		hRC=NULL;										// Set RC To NULL
	}

	if (hDC && !ReleaseDC(hWnd,hDC))					// Are We Able To Release The DC
	{
		MessageBox(NULL,"Release Device Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		hDC=NULL;										// Set DC To NULL
	}

	if (hWnd && !DestroyWindow(hWnd))					// Are We Able To Destroy The Window?
	{
		MessageBox(NULL,"Could Not Release hWnd.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		hWnd=NULL;										// Set hWnd To NULL
	}

	if (!UnregisterClass("OpenGL",hInstance))			// Are We Able To Unregister Class
	{
		MessageBox(NULL,"Could Not Unregister Class.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		hInstance=NULL;									// Set hInstance To NULL
	}
}

/*	This Code Creates Our OpenGL Window.  Parameters Are:					*
 *	title			- Title To Appear At The Top Of The Window				*
 *	width			- Width Of The GL Window Or Fullscreen Mode				*
 *	height			- Height Of The GL Window Or Fullscreen Mode			*
 *	bits			- Number Of Bits To Use For Color (8/16/24/32)			*
 *	fullscreenflag	- Use Fullscreen Mode (TRUE) Or Windowed Mode (FALSE)	*/
 
BOOL CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag)
{
	GLuint		PixelFormat;			// Holds The Results After Searching For A Match
	WNDCLASS	wc;						// Windows Class Structure
	DWORD		dwExStyle;				// Window Extended Style
	DWORD		dwStyle;				// Window Style
	RECT		WindowRect;				// Grabs Rectangle Upper Left / Lower Right Values
	WindowRect.left=(long)0;			// Set Left Value To 0
	WindowRect.right=(long)width;		// Set Right Value To Requested Width
	WindowRect.top=(long)0;				// Set Top Value To 0
	WindowRect.bottom=(long)height;		// Set Bottom Value To Requested Height

	fullscreen=fullscreenflag;			// Set The Global Fullscreen Flag

	hInstance			= GetModuleHandle(NULL);				// Grab An Instance For Our Window
	wc.style			= CS_HREDRAW | CS_VREDRAW | CS_OWNDC;	// Redraw On Size, And Own DC For Window.
	wc.lpfnWndProc		= (WNDPROC) WndProc;					// WndProc Handles Messages
	wc.cbClsExtra		= 0;									// No Extra Window Data
	wc.cbWndExtra		= 0;									// No Extra Window Data
	wc.hInstance		= hInstance;							// Set The Instance
	wc.hIcon			= LoadIcon(NULL, IDI_WINLOGO);			// Load The Default Icon
	wc.hCursor			= LoadCursor(NULL, IDC_ARROW);			// Load The Arrow Pointer
	wc.hbrBackground	= NULL;									// No Background Required For GL
	wc.lpszMenuName		= NULL;									// We Don't Want A Menu
	wc.lpszClassName	= "OpenGL";								// Set The Class Name

	if (!RegisterClass(&wc))									// Attempt To Register The Window Class
	{
		MessageBox(NULL,"Failed To Register The Window Class.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;											// Return FALSE
	}
	
	if (fullscreen)												// Attempt Fullscreen Mode?
	{
		DEVMODE dmScreenSettings;								// Device Mode
		memset(&dmScreenSettings,0,sizeof(dmScreenSettings));	// Makes Sure Memory's Cleared
		dmScreenSettings.dmSize=sizeof(dmScreenSettings);		// Size Of The Devmode Structure
		dmScreenSettings.dmPelsWidth	= width;				// Selected Screen Width
		dmScreenSettings.dmPelsHeight	= height;				// Selected Screen Height
		dmScreenSettings.dmBitsPerPel	= bits;					// Selected Bits Per Pixel