Jeff Molofee - NeHe's OpenGL Tutorials

0, // Orientation Angle

FW_BOLD, // Font Weight

FALSE, // Italic

FALSE, // Underline

FALSE, // Strikeout

This is the magic line! Instead of using ANSI_CHARSET like we did in tutorial 14, we're going to use SYMBOL_CHARSET. This tells Windows that the font we are building is not your typical font made up of characters. A symbol font is usually made up of tiny pictures (symbols). If you forget to change this line, wingdings, webdings and any other symbol font you may be trying to use will not work.

SYMBOL_CHARSET, // Character Set Identifier ( Modified )

The next few lines have not changed.

OUT_TT_PRECIS, // Output Precision

CLIP_DEFAULT_PRECIS, // Clipping Precision

ANTIALIASED_QUALITY, // Output Quality

FF_DONTCARE|DEFAULT_PITCH, // Family And Pitch

Now that we've selected the symbol character set identifier, we can select the wingdings font!

"Wingdings"); // Font Name ( Modified )

The remaining lines of code have not changed.

SelectObject(hDC, font); // Selects The Font We Created

wglUseFontOutlines(hDC, // Select The Current DC

0, // Starting Character

255, // Number Of Display Lists To Build

base, // Starting Display Lists

I'm allowing for more deviation. This means GL will not try to follow the outline of the font as closely. If you set deviation to 0.0f, you'll notice problems with the texturing on really curved surfaces. If you allow for some deviation, most of the problems will disappear.

0.1f, // Deviation From The True Outlines

The next three lines of code are still the same.

0.2f, // Font Thickness In The Z Direction

WGL_FONT_POLYGONS, // Use Polygons, Not Lines

gmf); // Address Of Buffer To Recieve Data

}

Right before ReSizeGLScene() we're going to add the following section of code to load our texture. You might recognize the code from previous tutorials. We create storage for the bitmap image. We load the bitmap image. We tell OpenGL to generate 1 texture, and we store this texture in texture[0].

I'm creating a mipmapped texture only because it looks better. The name of the texture is lights.bmp.

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

if (TextureImage[0]=LoadBMP("Data/Lights.bmp")) // Load The Bitmap

{

Status=TRUE; // Set The Status To TRUE

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

// Build Linear Mipmapped Texture

glBindTexture(GL_TEXTURE_2D, texture[0]);

gluBuild2DMipmaps(GL_TEXTURE_2D, 3, TextureImage[0]->sizeX, TextureImage[0]->sizeY, GL_RGB, GL_UNSIGNED_BYTE, TextureImage[0]->data);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST);

The next four lines of code will automatically generate texture coordinates for any object we draw to the screen. The glTexGen command is extremely powerful, and complex, and to get into all the math involved would be a tutorial on it's own. All you need to know is that GL_S and GL_T are texture coordinates. By default they are set up to take the current x location on the screen and the current y location on the screen and come up with a texture vertex. You'll notice the objects are not textured on the z plane… just stripes appear. The front and back faces are textured though, and that's all that matters. X (GL_S) will cover mapping the texture left to right, and Y (GL_T) will cover mapping the texture up and down.

GL_TEXTURE_GEN_MODE lets us select the mode of texture mapping we want to use on the S and T texture coordinates. You have 3 choices:

GL_EYE_LINEAR — The texture is fixed to the screen. It never moves. The object is mapped with whatever section of the texture it is passing over.

GL_OBJECT_LINEAR — This is the mode we are using. The texture is fixed to the object moving around the screen.

GL_SPHERE_MAP — Everyones favorite. Creates a metalic reflective type object.

It's important to note that I'm leaving out alot of code. We should be setting the GL_OBJECT_PLANE as well, but by default it's set to the parameters we want. Buy a good book if you're interested in learning more, or check out the MSDN help CD / DVD.

// Texturing Contour Anchored To The Object

glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);

// Texturing Contour Anchored To The Object

glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);

glEnable(GL_TEXTURE_GEN_S); // Auto Texture Generation

glEnable(GL_TEXTURE_GEN_T); // Auto Texture Generation

}

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

}

There are a few new lines at the end of the InitGL() code. BuildFont() has been moved underneath our texture loading code. The line glEnable(GL_COLOR_MATERIAL) has been removed. If you plan to apply colors to the texture using glColor3f(r,g,b) add the line glEnable(GL_COLOR_MATERIAL) back into this section of code.

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

glShadeModel(GL_SMOOTH); // Enable Smooth Shading

glClearColor(0.0f, 0.0f, 0.0f, 0.5f); // Black Background

glClearDepth(1.0f); // Depth Buffer Setup

glEnable(GL_DEPTH_TEST); // Enables Depth Testing

glDepthFunc(GL_LEQUAL); // The Type Of Depth Testing To Do

glEnable(GL_LIGHT0); // Quick And Dirty Lighting (Assumes Light0 Is Set Up)

glEnable(GL_LIGHTING); // Enable Lighting

glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really Nice Perspective Calculations

Enable 2D Texture Mapping, and select texture one. This will map texture one onto any 3D object we draw to the screen. If you want more control, you can enable and disable texture mapping yourself.