Jeff Molofee - NeHe's OpenGL Tutorials

if (!LoadGLTextures()) // Jump To Texture Loading Routine

{

return FALSE; // If Texture Didn't Load Return FALSE

}

If there were no errors, we jump to our font building code. Not much can go wrong when building the font so we don't bother with error checking.

BuildFont(); // Build The Font

Now we do our normal GL setup. We set the background clear color to black, the clear depth to 1.0. We choose a depth testing mode, along with a blending mode. We enable smooth shading, and finally we enable 2D texture mapping.

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

}

The section of code below will create our scene. We draw the 3D object first and the text last so that the text appears on top of the 3D object, instead of the 3D object covering up the text. The reason I decide to add a 3D object is to show that both perspective and ortho modes can be used at the same time.

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

We select our bumps.bmp texture so that we can build our simple little 3D object. We move into the screen 5 units so that we can see the 3D object. We rotate on the z axis by 45 degrees. This will rotate our quad 45 degrees clockwise and makes our quad look more like a diamond than a square.

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)

After we have done the 45 degree rotation, we spin the object on both the x axis and y axis based on the variable cnt1 times 30. This causes our object to spin around as if the diamond is spinning on a point.

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

We disable blending (we want the 3D object to appear solid), and set the color to bright white. We then draw a single texture mapped quad.

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

Immediately after we've drawn the first quad, we rotate 90 degrees on both the x axis and y axis. We then draw another quad. The second quad cuts through the middle of the first quad, creating a nice looking shape.

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

After both texture mapped quads have been drawn, we enable enable blending, and draw our text.

glEnable(GL_BLEND); // Enable Blending

glLoadIdentity(); // Reset The View

We use the same fancy coloring code from our other text tutorials. The color is changed gradually as the text moves across the screen.

// 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)));

Then we draw our text. We still use glPrint(). The first parameter is the x position. The second parameter is the y position. The third parameter ("NeHe") is the text to write to the screen, and the last parameter is the character set to use (0 – normal, 1 – italic).

As you can probably guess, we swing the text around the screen using COS and SIN, along with both counters cnt1 and cnt2. If you don't understand what SIN and COS do, go back and read the previous text tutorials.

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

We set the color to a dark blue and write the author's name at the bottom of the screen. We then write his name to the screen again using bright white letters. The white letters are a little to the right of the blue letters. This creates a shadowed look. (if blending wasn't enabled the effect wouldn't work).

glColor3f(0.0f,0.0f,1.0f); // Set Color To Red

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

The last thing we do is increase both our counters at different rates. This causes the text to move, and the 3D object to spin.

cnt1+=0.01f; // Increase The First Counter

cnt2+=0.0081f; // Increase The Second Counter

return TRUE; // Everything Went OK

}

The code in KillGLWindow(), CreateGLWindow() and WndProc() has not changed so we'll skip over it.

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

}

The title of our Window has changed.

// 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