lesson20.cpp

关于OpenGL的实例教程源代码

/*
 *		This Code Was Created By Jeff Molofee 2000
 *		And Modified By Giuseppe D'Agata ([e-mail])
 *		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 <math.h>			// Header File For Windows Math Library
#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	masking=TRUE;		// Masking On/Off
bool	mp;					// M Pressed?
bool	sp;					// Space Pressed?
bool	scene;				// Which Scene To Draw

GLuint	texture[5];			// Storage For Our Five Textures
GLuint	loop;				// Generic Loop Variable

GLfloat	roll;				// Rolling Texture

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[5];               // Create Storage Space For The Textures
        memset(TextureImage,0,sizeof(void *)*5);        // Set The Pointer To NULL

        if ((TextureImage[0]=LoadBMP("Data/logo.bmp")) &&	// Logo Texture
			(TextureImage[1]=LoadBMP("Data/mask1.bmp")) &&	// First Mask
			(TextureImage[2]=LoadBMP("Data/image1.bmp")) &&	// First Image
			(TextureImage[3]=LoadBMP("Data/mask2.bmp")) &&	// Second Mask
			(TextureImage[4]=LoadBMP("Data/image2.bmp")))	// Second Image
        {
                Status=TRUE;                            // Set The Status To TRUE
                glGenTextures(5, &texture[0]);          // Create Five Textures

				for (loop=0; loop<5; loop++)			// Loop Through All 5 Textures
				{
	                glBindTexture(GL_TEXTURE_2D, texture[loop]);
			        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[loop]->sizeX, TextureImage[loop]->sizeY, 0, GL_RGB, GL_UNSIGNED_BYTE, TextureImage[loop]->data);
				}
        }
		for (loop=0; loop<5; loop++)						// Loop Through All 5 Textures
		{
	        if (TextureImage[loop])							// If Texture Exists
		    {
			        if (TextureImage[loop]->data)			// If Texture Image Exists
				    {
					        free(TextureImage[loop]->data);	// Free The Texture Image Memory
					}
					free(TextureImage[loop]);				// 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
	gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);	// Calculate Window Aspect Ratio
	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
	}

	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);				// Clear The Background Color To Black
	glClearDepth(1.0);									// Enables Clearing Of The Depth Buffer
	glEnable(GL_DEPTH_TEST);							// Enable Depth Testing
	glShadeModel(GL_SMOOTH);							// Enables Smooth Color Shading
	glEnable(GL_TEXTURE_2D);							// Enable 2D Texture Mapping
	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
	glLoadIdentity();									// Reset The Modelview Matrix
	glTranslatef(0.0f,0.0f,-2.0f);						// Move Into The Screen 5 Units

	glBindTexture(GL_TEXTURE_2D, texture[0]);			// Select Our Logo Texture
	glBegin(GL_QUADS);									// Start Drawing A Textured Quad
		glTexCoord2f(0.0f, -roll+0.0f); glVertex3f(-1.1f, -1.1f,  0.0f);	// Bottom Left
		glTexCoord2f(3.0f, -roll+0.0f); glVertex3f( 1.1f, -1.1f,  0.0f);	// Bottom Right
		glTexCoord2f(3.0f, -roll+3.0f); glVertex3f( 1.1f,  1.1f,  0.0f);	// Top Right
		glTexCoord2f(0.0f, -roll+3.0f); glVertex3f(-1.1f,  1.1f,  0.0f);	// Top Left
	glEnd();											// Done Drawing The Quad

	glEnable(GL_BLEND);									// Enable Blending
	glDisable(GL_DEPTH_TEST);							// Disable Depth Testing

	if (masking)										// Is Masking Enabled?
	{
		glBlendFunc(GL_DST_COLOR,GL_ZERO);				// Blend Screen Color With Zero (Black)
	}

	if (scene)											// Are We Drawing The Second Scene?
	{
		glTranslatef(0.0f,0.0f,-1.0f);					// Translate Into The Screen One Unit
		glRotatef(roll*360,0.0f,0.0f,1.0f);				// Rotate On The Z Axis 360 Degrees.
		if (masking)									// Is Masking On?
		{
			glBindTexture(GL_TEXTURE_2D, texture[3]);	// Select The Second Mask Texture
			glBegin(GL_QUADS);							// Start Drawing A Textured Quad
				glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.1f, -1.1f,  0.0f);	// Bottom Left
				glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.1f, -1.1f,  0.0f);	// Bottom Right
				glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.1f,  1.1f,  0.0f);	// Top Right
				glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.1f,  1.1f,  0.0f);	// Top Left
			glEnd();									// Done Drawing The Quad
		}

		glBlendFunc(GL_ONE, GL_ONE);					// Copy Image 2 Color To The Screen
		glBindTexture(GL_TEXTURE_2D, texture[4]);		// Select The Second Image Texture
		glBegin(GL_QUADS);								// Start Drawing A Textured Quad
			glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.1f, -1.1f,  0.0f);	// Bottom Left
			glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.1f, -1.1f,  0.0f);	// Bottom Right
			glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.1f,  1.1f,  0.0f);	// Top Right
			glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.1f,  1.1f,  0.0f);	// Top Left
		glEnd();										// Done Drawing The Quad
	}
	else												// Otherwise
	{
		if (masking)									// Is Masking On?
		{
			glBindTexture(GL_TEXTURE_2D, texture[1]);	// Select The First Mask Texture
			glBegin(GL_QUADS);							// Start Drawing A Textured Quad
				glTexCoord2f(roll+0.0f, 0.0f); glVertex3f(-1.1f, -1.1f,  0.0f);	// Bottom Left
				glTexCoord2f(roll+4.0f, 0.0f); glVertex3f( 1.1f, -1.1f,  0.0f);	// Bottom Right
				glTexCoord2f(roll+4.0f, 4.0f); glVertex3f( 1.1f,  1.1f,  0.0f);	// Top Right
				glTexCoord2f(roll+0.0f, 4.0f); glVertex3f(-1.1f,  1.1f,  0.0f);	// Top Left
			glEnd();									// Done Drawing The Quad
		}

		glBlendFunc(GL_ONE, GL_ONE);					// Copy Image 1 Color To The Screen
		glBindTexture(GL_TEXTURE_2D, texture[2]);		// Select The First Image Texture
		glBegin(GL_QUADS);								// Start Drawing A Textured Quad
			glTexCoord2f(roll+0.0f, 0.0f); glVertex3f(-1.1f, -1.1f,  0.0f);	// Bottom Left
			glTexCoord2f(roll+4.0f, 0.0f); glVertex3f( 1.1f, -1.1f,  0.0f);	// Bottom Right
			glTexCoord2f(roll+4.0f, 4.0f); glVertex3f( 1.1f,  1.1f,  0.0f);	// Top Right
			glTexCoord2f(roll+0.0f, 4.0f); glVertex3f(-1.1f,  1.1f,  0.0f);	// Top Left
		glEnd();										// Done Drawing The Quad
	}

	glEnable(GL_DEPTH_TEST);							// Enable Depth Testing
	glDisable(GL_BLEND);								// Disable Blending

	roll+=0.002f;										// Increase Our Texture Roll Variable
	if (roll>1.0f)										// Is Roll Greater Than One
	{
		roll-=1.0f;										// Subtract 1 From Roll
	}

	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
	}