Jeff Molofee - NeHe's OpenGL Tutorials

}

Now for the drawing code. We start off by clearing the screen and the depth buffer. We call glLoadIdentity() to reset everything. Then we translate ten units into the screen. Outline fonts look great in perspective mode. The further into the screen you translate, the smaller the font becomes. The closer you translate, the larger the font becomes.

Outline fonts can also be manipulated by using the glScalef(x,y,z) command. If you want the font 2 times taller, use glScalef(1.0f,2.0f,1.0f). the 2.0f is on the y axis, which tells OpenGL to draw the list twice as tall. If the 2.0f was on the x axis, the character would be twice as wide.

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 View

glTranslatef(0.0f,0.0f,-10.0f); // Move Ten Units Into The Screen

After we've translated into the screen, we want the text to spin. The next 3 lines rotate the screen on all three axes. I multiply rot by different numbers to make each rotation happen at a different speed.

glRotatef(rot,1.0f,0.0f,0.0f); // Rotate On The X Axis

glRotatef(rot*1.5f,0.0f,1.0f,0.0f); // Rotate On The Y Axis

glRotatef(rot*1.4f,0.0f,0.0f,1.0f); // Rotate On The Z Axis

Now for the crazy color cycling. As usual, I make use of the only variable that counts up (rot). The colors pulse up and down using COS and SIN. I divide the value of rot by different numbers so that each color isn't increasing at the same speed. The final results are nice.

// Pulsing Colors Based On The Rotation

glColor3f(1.0f*float(cos(rot/20.0f)), 1.0f*float(sin(rot/25.0f)), 1.0f-0.5f*float(cos(rot/17.0f)));

My favorite part… Writing the text to the screen. I've used the same command we used to write Bitmap fonts to the screen. All you have to do to write the text to the screen is glPrint("{any text you want}"). It's that easy!

In the code below we'll print NeHe, a space, a dash, a space, and then whatever number is stored in rot divided by 50 (to slow down the counter a bit). If the number is larger that 999.99 the 4th digit to the left will be cut off (we're requesting only 3 digits to the left of the decimal place). Only 2 digits will be displayed after the decimal place.

glPrint("NeHe – %3.2f",rot/50); // Print GL Text To The Screen

Then we increase the rotation variable so the colors pulse and the text spins.

rot+=0.5f; // Increase The Rotation Variable

return TRUE; // Everything Went OK

}

The last thing to do is add KillFont() to the end of KillGLWindow() just like I'm showing below. It's important to add this line. It cleans things up before we exit our program.

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

}

At the end of this tutorial you should be able to use Outline Fonts in your own OpenGL projects. Just like lesson 13, I've searched the net looking for a tutorial similar to this one, and have found nothing. Could my site be the first to cover this topic in great detail while explaining everything in easy to understand C code? Enjoy the tutorial, and happy coding!

* DOWNLOAD Visual C++Code For This Lesson.

* DOWNLOAD Borland C++Code For This Lesson. (Conversion by Patrick Salmons)

* DOWNLOAD DelphiCode For This Lesson. (Conversion by Marc Aarts)

* DOWNLOAD Game GLUTCode For This Lesson. (Conversion by Milikas Anastasios)

* DOWNLOAD JavaCode For This Lesson. (Conversion by Jeff Kirby)

* DOWNLOAD Mac OSCode For This Lesson. (Conversion by Anthony Parker)

* DOWNLOAD Visual BasicCode For This Lesson. (Conversion by Ross Dawson)

* DOWNLOAD Visual BasicCode For This Lesson. (Conversion by Edo)

After posting the last two tutorials on bitmap and outlined fonts, I received quite a few emails from people wondering how they could texture map the fonts. You can use autotexture coordinate generation. This will generate texture coordinates for each of the polygons on the font.

A small note, this code is Windows specific. It uses the wgl functions of Windows to build the font. Apparently Apple has agl support that should do the same thing, and X has glx. Unfortunately I can't guarantee this code is portable. If anyone has platform independant code to draw fonts to the screen, send it my way and I'll write another font tutorial.

We'll build our Texture Font demo using the code from lesson 14. If any of the code has changed in a particular section of the program, I'll rewrite the entire section of code so that it's easier to see the changes that I have made.

The following section of code is similar to the code in lesson 14, but this time we're not going to include the stdarg.h file.

#include // Header File For Windows

#include // Header File For Windows Math Library

#include // Header File For Standard Input/Output

#include // Header File For The OpenGL32 Library

#include // Header File For The GLu32 Library

#include // 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

We're going to add one new integer variable here called texture[ ]. It will be used to store our texture. The last three lines were in tutorial 14 and have not changed in this tutorial.

GLuint texture[1]; // One Texture Map ( NEW )

GLuint base; // Base Display List For The Font Set

GLfloat rot; // Used To Rotate The Text

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

The following section of code has some minor changes. In this tutorial I'm going to use the wingdings font to display a skull and crossbones type object. If you want to display text instead, you can leave the code the same as it was in lesson 14, or change to a font of your own.

A few of you were wondering how to use the wingdings font, which is another reason I'm not using a standard font. Wingdings is a SYMBOL font, and requires a few changes to make it work. It's not as easy as telling Windows to use the wingdings font. If you change the font name to wingdings, you'll notice that the font doesn't get selected. You have to tell Windows that the font is a symbol font and not a standard character font. More on this later.

GLvoid BuildFont(GLvoid) // Build Our Bitmap Font

{

GLYPHMETRICSFLOAT gmf[256]; // Address Buffer For Font Storage

HFONT font; // Windows Font ID

base = glGenLists(256); // Storage For 256 Characters

font = CreateFont(–12, // Height Of Font

0, // Width Of Font

0, // Angle Of Escapement