NeHe Productions: OpenGL Lesson #17

#include <windows.h>								 // Header File For Windows
#include <math.h>								 // Header File For Windows Math Library		( ADD )
#include <stdio.h>								 // Header File For Standard Input/Output	( ADD )
#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

GLuint	base;									 // Base Display List For The Font
GLuint	texture[2];								 // Storage For Our Font Texture
GLuint	loop;									 // Generic Loop Variable
GLfloat	cnt1;									 // 1st Counter Used To Move Text & For Coloring
GLfloat	cnt2;									 // 2nd Counter Used To Move Text & For Coloring
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[2];					 // Create Storage Space For The Textures

	memset(TextureImage,0,sizeof(void *)*2);				 // Set The Pointer To NULL
	if ((TextureImage[0]=LoadBMP("Data/Font.bmp")) &&			 // Load The Font Bitmap
		(TextureImage[1]=LoadBMP("Data/Bumps.bmp")))			 // Load The Texture Bitmap
	{
		Status=TRUE;							 // Set The Status To TRUE

		glGenTextures(2, &texture[0]);					 // Create Two Texture
		for (loop=0; loop<2; loop++)					 // Loop Through All The Textures
		{
			 // Build All The 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<2; loop++)
		{
	 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 BuildFont(GLvoid)							 // Build Our Font Display List
{

	float	cx;								 // Holds Our X Character Coord
	float	cy;								 // Holds Our Y Character Coord

	base=glGenLists(256);							 // Creating 256 Display Lists
	glBindTexture(GL_TEXTURE_2D, texture[0]);				 // Select Our Font Texture

	for (loop=0; loop<256; loop++)						 // Loop Through All 256 Lists
	{

		cx=float(loop%16)/16.0f;					 // X Position Of Current Character
		cy=float(loop/16)/16.0f;					 // Y Position Of Current Character

		glNewList(base+loop,GL_COMPILE);				 // Start Building A List

			glBegin(GL_QUADS);					 // Use A Quad For Each Character

				glTexCoord2f(cx,1-cy-0.0625f);			 // Texture Coord (Bottom Left)
				glVertex2i(0,0);				 // Vertex Coord (Bottom Left)

				glTexCoord2f(cx+0.0625f,1-cy-0.0625f);		 // Texture Coord (Bottom Right)
				glVertex2i(16,0);				 // Vertex Coord (Bottom Right)

				glTexCoord2f(cx+0.0625f,1-cy);			 // Texture Coord (Top Right)
				glVertex2i(16,16);				 // Vertex Coord (Top Right)

				glTexCoord2f(cx,1-cy);				 // Texture Coord (Top Left)
				glVertex2i(0,16);				 // Vertex Coord (Top Left)
			glEnd();						 // Done Building Our Quad (Character)

			glTranslated(10,0,0);					 // Move To The Right Of The Character
		glEndList();							 // Done Building The Display List
	}									 // Loop Until All 256 Are Built
}

GLvoid KillFont(GLvoid)								 // Delete The Font From Memory
{
	glDeleteLists(base,256);						 // Delete All 256 Display Lists
}

GLvoid glPrint(GLint x, GLint y, char *string, int set)				 // Where The Printing Happens
{

	if (set>1)								 // Is set Greater Than One?
	{
		set=1;								 // If So, Make Set Equal One
	}

	glBindTexture(GL_TEXTURE_2D, texture[0]);				 // Select Our Font Texture

	glDisable(GL_DEPTH_TEST);						 // Disables Depth Testing

	glMatrixMode(GL_PROJECTION);						 // Select The Projection Matrix
	glPushMatrix();								 // Store The Projection Matrix

	glLoadIdentity();							 // Reset The Projection Matrix
	glOrtho(0,640,0,480,-1,1);						 // Set Up An Ortho Screen

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

	glTranslated(x,y,0);							 // Position The Text (0,0 - Bottom Left)

	glListBase(base-32+(128*set));						 // Choose The Font Set (0 or 1)

	glCallLists(strlen(string),GL_UNSIGNED_BYTE,string);			 // Write The Text To The Screen

	glMatrixMode(GL_PROJECTION);						 // Select The Projection Matrix
	glPopMatrix();								 // Restore The Old Projection Matrix

	glMatrixMode(GL_MODELVIEW);						 // Select The Modelview Matrix
	glPopMatrix();								 // Restore The Old Projection Matrix

	glEnable(GL_DEPTH_TEST);						 // Enables Depth Testing
}

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
	}

	BuildFont();								 // Build The Font

	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);					 // Clear The Background Color To Black
	glClearDepth(1.0);							 // Enables Clearing Of The Depth Buffer
	glDepthFunc(GL_LEQUAL);							 // The Type Of Depth Test To Do
	glBlendFunc(GL_SRC_ALPHA,GL_ONE);					 // Select The Type Of Blending
	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

	glBindTexture(GL_TEXTURE_2D, texture[1]);				 // Select Our Second Texture
	glTranslatef(0.0f,0.0f,-5.0f);						 // Move Into The Screen 5 Units
	glRotatef(45.0f,0.0f,0.0f,1.0f);					 // Rotate On The Z Axis 45 Degrees (Clockwise)

	glRotatef(cnt1*30.0f,1.0f,1.0f,0.0f);					 // Rotate On The X & Y Axis By cnt1 (Left To Right)

	glDisable(GL_BLEND);							 // Disable Blending Before We Draw In 3D
	glColor3f(1.0f,1.0f,1.0f);						 // Bright White
	glBegin(GL_QUADS);							 // Draw Our First Texture Mapped Quad
		glTexCoord2d(0.0f,0.0f);					 // First Texture Coord
		glVertex2f(-1.0f, 1.0f);					 // First Vertex
		glTexCoord2d(1.0f,0.0f);					 // Second Texture Coord
		glVertex2f( 1.0f, 1.0f);					 // Second Vertex
		glTexCoord2d(1.0f,1.0f);					 // Third Texture Coord
		glVertex2f( 1.0f,-1.0f);					 // Third Vertex
		glTexCoord2d(0.0f,1.0f);					 // Fourth Texture Coord
		glVertex2f(-1.0f,-1.0f);					 // Fourth Vertex
	glEnd();								 // Done Drawing The First Quad

	glRotatef(90.0f,1.0f,1.0f,0.0f);					 // Rotate On The X & Y Axis By 90 Degrees (Left To Right)
	glBegin(GL_QUADS);							 // Draw Our Second Texture Mapped Quad
		glTexCoord2d(0.0f,0.0f);					 // First Texture Coord
		glVertex2f(-1.0f, 1.0f);					 // First Vertex
		glTexCoord2d(1.0f,0.0f);					 // Second Texture Coord
		glVertex2f( 1.0f, 1.0f);					 // Second Vertex
		glTexCoord2d(1.0f,1.0f);					 // Third Texture Coord
		glVertex2f( 1.0f,-1.0f);					 // Third Vertex
		glTexCoord2d(0.0f,1.0f);					 // Fourth Texture Coord
		glVertex2f(-1.0f,-1.0f);					 // Fourth Vertex
	glEnd();								 // Done Drawing Our Second Quad

	glEnable(GL_BLEND);							 // Enable Blending
	glLoadIdentity();							 // Reset The View

	 // Pulsing Colors Based On Text Position
	glColor3f(1.0f*float(cos(cnt1)),1.0f*float(sin(cnt2)),1.0f-0.5f*float(cos(cnt1+cnt2)));

	glPrint(int((280+250*cos(cnt1))),int(235+200*sin(cnt2)),"NeHe",0);	 // Print GL Text To The Screen
	glColor3f(1.0f*float(sin(cnt2)),1.0f-0.5f*float(cos(cnt1+cnt2)),1.0f*float(cos(cnt1)));
	glPrint(int((280+230*cos(cnt2))),int(235+200*sin(cnt1)),"OpenGL",1);	 // Print GL Text To The Screen

	glColor3f(0.0f,0.0f,1.0f);						 // Set Color To Blue
	glPrint(int(240+200*cos((cnt2+cnt1)/5)),2,"Giuseppe D'Agata",0);	 // Draw Text To The Screen
	glColor3f(1.0f,1.0f,1.0f);						 // Set Color To White
	glPrint(int(242+200*cos((cnt2+cnt1)/5)),2,"Giuseppe D'Agata",0);	 // Draw Offset Text To The Screen

	cnt1+=0.01f;								 // Increase The First Counter
	cnt2+=0.0081f;								 // Increase The Second Counter
	return TRUE;								 // Everything Went OK
}

int WINAPI WinMain(	HINSTANCE	hInstance,				 // Instance
			HINSTANCE	hPrevInstance,				 // Previous Instance
			LPSTR		lpCmdLine,				 // Command Line Parameters
			int		nCmdShow)				 // Window Show State
{
	MSG		msg;							 // Windows Message Structure
	BOOL	done=FALSE;							 // Bool Variable To Exit Loop
	 // Ask The User Which Screen Mode They Prefer
	if (MessageBox(NULL,"Would You Like To Run In Fullscreen Mode?", "Start FullScreen?",MB_YESNO|MB_ICONQUESTION)==IDNO)
	{
		fullscreen=FALSE;						 // Windowed Mode
	}

	 // Create Our OpenGL Window
	if (!CreateGLWindow("NeHe & Giuseppe D'Agata's 2D Font Tutorial",640,480,16,fullscreen))
	{
		return 0;							 // Quit If Window Was Not Created
	}
	while(!done)								 // Loop That Runs While done=FALSE
	{
		if (PeekMessage(&msg,NULL,0,0,PM_REMOVE))			 // Is There A Message Waiting?
		{
			if (msg.message==WM_QUIT)				 // Have We Received A Quit Message?
			{
				done=TRUE;					 // If So done=TRUE
			}
			else							 // If Not, Deal With Window Messages
			{
				TranslateMessage(&msg);				 // Translate The Message
				DispatchMessage(&msg);				 // Dispatch The Message
			}
		}
		else								 // If There Are No Messages
		{
			 // Draw The Scene. Watch For ESC Key And Quit Messages From DrawGLScene()
			if ((active && !DrawGLScene()) || keys[VK_ESCAPE])	 // Active? Was There A Quit Received?
			{
				done=TRUE;					 // ESC or DrawGLScene Signalled A Quit
			}
			else							 // Not Time To Quit, Update Screen
			{
				SwapBuffers(hDC);				 // Swap Buffers (Double Buffering)
			}
		}
	}
	 // Shutdown

	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
	}
	KillFont();								 // Destroy The Font
}