lesson26.cpp

关于OpenGL的实例教程源代码

/*		This code has been created by Banu Octavian aka Choko - 20 may 2000
 *		and uses NeHe tutorials as a starting point (window initialization,
 *		texture loading, GL initialization and code for keypresses) - very good
 *		tutorials, Jeff. If anyone is interested about the presented algorithm
 *		please e-mail me at [e-mail]
 *
 *		Code Commmenting And Clean Up By Jeff Molofee ( NeHe )
 *		NeHe Productions	...		http://nehe.gamedev.net
 */

#include <windows.h>									// Header File For Windows
#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
#include <stdio.h>										// Header File For Standard Input / Output

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

// Light Parameters
static GLfloat LightAmb[] = {0.7f, 0.7f, 0.7f, 1.0f};	// Ambient Light
static GLfloat LightDif[] = {1.0f, 1.0f, 1.0f, 1.0f};	// Diffuse Light
static GLfloat LightPos[] = {4.0f, 4.0f, 6.0f, 1.0f};	// Light Position

GLUquadricObj	*q;										// Quadratic For Drawing A Sphere

GLfloat		xrot		=  0.0f;						// X Rotation
GLfloat		yrot		=  0.0f;						// Y Rotation
GLfloat		xrotspeed	=  0.0f;						// X Rotation Speed
GLfloat		yrotspeed	=  0.0f;						// Y Rotation Speed
GLfloat		zoom		= -7.0f;						// Depth Into The Screen
GLfloat		height		=  2.0f;						// Height Of Ball From Floor

GLuint		texture[3];									// 3 Textures

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

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
}

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[3];					// Create Storage Space For The Textures
    memset(TextureImage,0,sizeof(void *)*3);			// Set The Pointer To NULL
    if ((TextureImage[0]=LoadBMP("Data/EnvWall.bmp")) &&// Load The Floor Texture
        (TextureImage[1]=LoadBMP("Data/Ball.bmp")) &&	// Load the Light Texture
        (TextureImage[2]=LoadBMP("Data/EnvRoll.bmp")))	// Load the Wall Texture
	{   
		Status=TRUE;									// Set The Status To TRUE
		glGenTextures(3, &texture[0]);					// Create The Texture
		for (int loop=0; loop<3; loop++)				// Loop Through 5 Textures
		{
			glBindTexture(GL_TEXTURE_2D, texture[loop]);
			glTexImage2D(GL_TEXTURE_2D, 0, 3, TextureImage[loop]->sizeX, TextureImage[loop]->sizeY, 0, GL_RGB, GL_UNSIGNED_BYTE, TextureImage[loop]->data);
			glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
			glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
		}
		for (loop=0; loop<3; loop++)					// Loop Through 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
}

int InitGL(GLvoid)										// All Setup For OpenGL Goes Here
{
	if (!LoadGLTextures())								// If Loading The Textures Failed
	{
		return FALSE;									// Return False
	}
	glShadeModel(GL_SMOOTH);							// Enable Smooth Shading
	glClearColor(0.2f, 0.5f, 1.0f, 1.0f);				// Background
	glClearDepth(1.0f);									// Depth Buffer Setup
	glClearStencil(0);									// Clear The Stencil Buffer To 0
	glEnable(GL_DEPTH_TEST);							// Enables Depth Testing
	glDepthFunc(GL_LEQUAL);								// The Type Of Depth Testing To Do
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);	// Really Nice Perspective Calculations
	glEnable(GL_TEXTURE_2D);							// Enable 2D Texture Mapping

	glLightfv(GL_LIGHT0, GL_AMBIENT, LightAmb);			// Set The Ambient Lighting For Light0
	glLightfv(GL_LIGHT0, GL_DIFFUSE, LightDif);			// Set The Diffuse Lighting For Light0
	glLightfv(GL_LIGHT0, GL_POSITION, LightPos);		// Set The Position For Light0

	glEnable(GL_LIGHT0);								// Enable Light 0
	glEnable(GL_LIGHTING);								// Enable Lighting

	q = gluNewQuadric();								// Create A New Quadratic
	gluQuadricNormals(q, GL_SMOOTH);					// Generate Smooth Normals For The Quad
	gluQuadricTexture(q, GL_TRUE);						// Enable Texture Coords For The Quad

	glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP);	// Set Up Sphere Mapping
	glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP);	// Set Up Sphere Mapping

	return TRUE;										// Initialization Went OK
}

void DrawObject()										// Draw Our Ball
{
	glColor3f(1.0f, 1.0f, 1.0f);						// Set Color To White
	glBindTexture(GL_TEXTURE_2D, texture[1]);			// Select Texture 2 (1)
	gluSphere(q, 0.35f, 32, 16);						// Draw First Sphere

	glBindTexture(GL_TEXTURE_2D, texture[2]);			// Select Texture 3 (2)
	glColor4f(1.0f, 1.0f, 1.0f, 0.4f);					// Set Color To White With 40% Alpha
	glEnable(GL_BLEND);									// Enable Blending
	glBlendFunc(GL_SRC_ALPHA, GL_ONE);					// Set Blending Mode To Mix Based On SRC Alpha
	glEnable(GL_TEXTURE_GEN_S);							// Enable Sphere Mapping
	glEnable(GL_TEXTURE_GEN_T);							// Enable Sphere Mapping

	gluSphere(q, 0.35f, 32, 16);						// Draw Another Sphere Using New Texture
														// Textures Will Mix Creating A MultiTexture Effect (Reflection)
	glDisable(GL_TEXTURE_GEN_S);						// Disable Sphere Mapping
	glDisable(GL_TEXTURE_GEN_T);						// Disable Sphere Mapping
	glDisable(GL_BLEND);								// Disable Blending
}

void DrawFloor()										// Draws The Floor
{
	glBindTexture(GL_TEXTURE_2D, texture[0]);			// Select Texture 1 (0)
	glBegin(GL_QUADS);									// Begin Drawing A Quad
		glNormal3f(0.0, 1.0, 0.0);						// Normal Pointing Up
			glTexCoord2f(0.0f, 1.0f);					// Bottom Left Of Texture
			glVertex3f(-2.0, 0.0, 2.0);					// Bottom Left Corner Of Floor
			
			glTexCoord2f(0.0f, 0.0f);					// Top Left Of Texture
			glVertex3f(-2.0, 0.0,-2.0);					// Top Left Corner Of Floor
			
			glTexCoord2f(1.0f, 0.0f);					// Top Right Of Texture
			glVertex3f( 2.0, 0.0,-2.0);					// Top Right Corner Of Floor
			
			glTexCoord2f(1.0f, 1.0f);					// Bottom Right Of Texture
			glVertex3f( 2.0, 0.0, 2.0);					// Bottom Right Corner Of Floor
	glEnd();											// Done Drawing The Quad
}

int DrawGLScene(GLvoid)									// Draw Everything
{
	// Clear Screen, Depth Buffer & Stencil Buffer
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);

	// Clip Plane Equations
	double eqr[] = {0.0f,-1.0f, 0.0f, 0.0f};			// Plane Equation To Use For The Reflected Objects

	glLoadIdentity();									// Reset The Modelview Matrix
	glTranslatef(0.0f, -0.6f, zoom);					// Zoom And Raise Camera Above The Floor (Up 0.6 Units)
	glColorMask(0,0,0,0);								// Set Color Mask
	glEnable(GL_STENCIL_TEST);							// Enable Stencil Buffer For "marking" The Floor
	glStencilFunc(GL_ALWAYS, 1, 1);						// Always Passes, 1 Bit Plane, 1 As Mask
	glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);			// We Set The Stencil Buffer To 1 Where We Draw Any Polygon
														// Keep If Test Fails, Keep If Test Passes But Buffer Test Fails
														// Replace If Test Passes
	glDisable(GL_DEPTH_TEST);							// Disable Depth Testing
	DrawFloor();										// Draw The Floor (Draws To The Stencil Buffer)
														// We Only Want To Mark It In The Stencil Buffer
	glEnable(GL_DEPTH_TEST);							// Enable Depth Testing
	glColorMask(1,1,1,1);								// Set Color Mask to TRUE, TRUE, TRUE, TRUE
	glStencilFunc(GL_EQUAL, 1, 1);						// We Draw Only Where The Stencil Is 1
														// (I.E. Where The Floor Was Drawn)
	glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);				// Don't Change The Stencil Buffer
	glEnable(GL_CLIP_PLANE0);							// Enable Clip Plane For Removing Artifacts
														// (When The Object Crosses The Floor)
	glClipPlane(GL_CLIP_PLANE0, eqr);					// Equation For Reflected Objects
	glPushMatrix();										// Push The Matrix Onto The Stack
		glScalef(1.0f, -1.0f, 1.0f);					// Mirror Y Axis
		glLightfv(GL_LIGHT0, GL_POSITION, LightPos);	// Set Up Light0
		glTranslatef(0.0f, height, 0.0f);				// Position The Object
		glRotatef(xrot, 1.0f, 0.0f, 0.0f);				// Rotate Local Coordinate System On X Axis
		glRotatef(yrot, 0.0f, 1.0f, 0.0f);				// Rotate Local Coordinate System On Y Axis
		DrawObject();									// Draw The Sphere (Reflection)
	glPopMatrix();										// Pop The Matrix Off The Stack
	glDisable(GL_CLIP_PLANE0);							// Disable Clip Plane For Drawing The Floor
	glDisable(GL_STENCIL_TEST);							// We Don't Need The Stencil Buffer Any More (Disable)
	glLightfv(GL_LIGHT0, GL_POSITION, LightPos);		// Set Up Light0 Position
	glEnable(GL_BLEND);									// Enable Blending (Otherwise The Reflected Object Wont Show)
	glDisable(GL_LIGHTING);								// Since We Use Blending, We Disable Lighting
	glColor4f(1.0f, 1.0f, 1.0f, 0.8f);					// Set Color To White With 80% Alpha
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);	// Blending Based On Source Alpha And 1 Minus Dest Alpha
	DrawFloor();										// Draw The Floor To The Screen
	glEnable(GL_LIGHTING);								// Enable Lighting
	glDisable(GL_BLEND);								// Disable Blending
	glTranslatef(0.0f, height, 0.0f);					// Position The Ball At Proper Height
	glRotatef(xrot, 1.0f, 0.0f, 0.0f);					// Rotate On The X Axis
	glRotatef(yrot, 0.0f, 1.0f, 0.0f);					// Rotate On The Y Axis
	DrawObject();										// Draw The Ball
	xrot += xrotspeed;									// Update X Rotation Angle By xrotspeed
	yrot += yrotspeed;									// Update Y Rotation Angle By yrotspeed
	glFlush();											// Flush The GL Pipeline
	return TRUE;										// Everything Went OK
}

void ProcessKeyboard()									// Process Keyboard Results
{
	if (keys[VK_RIGHT])		yrotspeed += 0.08f;			// Right Arrow Pressed (Increase yrotspeed)
	if (keys[VK_LEFT])		yrotspeed -= 0.08f;			// Left Arrow Pressed (Decrease yrotspeed)
	if (keys[VK_DOWN])		xrotspeed += 0.08f;			// Down Arrow Pressed (Increase xrotspeed)
	if (keys[VK_UP])		xrotspeed -= 0.08f;			// Up Arrow Pressed (Decrease xrotspeed)

	if (keys['A'])			zoom +=0.05f;				// 'A' Key Pressed ... Zoom In
	if (keys['Z'])			zoom -=0.05f;				// 'Z' Key Pressed ... Zoom Out

	if (keys[VK_PRIOR])		height +=0.03f;				// Page Up Key Pressed Move Ball Up
	if (keys[VK_NEXT])		height -=0.03f;				// Page Down Key Pressed Move Ball Down
}

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

	if (!UnregisterClass("OpenGL",hInstance))			// Are We Able To Unregister Class