Teach Yourself Game Programming in 21 Days
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André LaMothe's "Teach Yourself Game Programming in 21 Days"

Here's my trek through this great book from 1996.


I used Borland's Turbo C v2.01 to compile the examples. I also needed to set the memory model to 'Large' so it could see the far pointers.

André used Microsoft C/C++ 7.0; several things have to be changed for this to work in TC:

MSCC7 TC2 Comment
<memory.h> <mem.h> not sure this has identical functions
_bios_keybrd bioskey
_ffree farfree
_fmalloc farmalloc
_fmemset memset doesn't seem to be a far * memset
_inp inp
_int86 int86
_outp outp

Also, TC doesn't support // single line comments, so it's /* olde schoole time */.


  • Chapter 3, Exercise 5: Try to make Plot_Pixel_Fast() even faster!
  • Chapter 3, Exercise 6: Using the keyboard as an input device, try to mkae a crude drawing program that allows the user to change colors and move a pen on the screen.
  • Chapter 4, Exercise 1: Write a function that scales a sprite.
  • Chapter 4, Exercise 2: Write a program that places a PCX file on the screen and then fades to black when a key is pressed.
  • Chapter 4, Exercise 3: Write a function named Sprite_Fizz() that makes a sprite fizzle away in 25 cycles.
  • Chapter 4, Exercise 4: When the tanks collide in the Attank!!! demo, nothing happens. Make something spectacular happen when the tanks collide.
  • Chapter 4, Exercise 5: Create a starfield that looks like the one in the shuttle.exe program (?); that is, one that swings around. Then, place a sprite of a spaceship with glowing engines in the center of the starfield. (Hint: use color-register animation to make the engines glow.)
  • Chapter 5, Exercise 1: Write a function that draws a circle of any radius.
  • Chapter 5, Exercise 2: Write a function that scales polygons differently on each axis; that is, there's a separate scaling function for both the x- and y-axis.
  • Chapter 5, Exercise 3: Time and analyze the difference in performance between Draw_Polygon() and Draw_Polygon_Clip().
  • Chapter 5, Exercise 4: Make the ship in rockdemo fire missiles.
  • Chapter 5, Exercise 5: Place a black hole into rockdemo by creating a local gravity field somewhere on the screen.
  • Chapter 5, Exercise 6: Extra Credit: see if you can derive the rotation equations.
  • Chapter 6, Exercise 2: Modify the robo.c program so that when Robopunk walks all the way to the right edge of the universe, he falls downward instead of floating in mid-air.
  • Chapter 6, Exercise 3: Write a function that adds a starfield to robo.c.
  • Chapter 6, Exercise 4: Modify the Dissolve() screen transition function so that it dissolves the screen with any color.
  • Chapter 6, Exercise 5: Modify the fading-light function so it increases the intensity of all the color registers until they're saturated.
  • Chapter 6, Exercise 6: Extra Credit: Try to make Robopunk jump in a parabolic path. (Hint: use the fact that position = yo + velocity * time + 1/2 * acceleration * time^2.)
  • Chapter 7, Exercise 1: Write a program that prints out the bit pattern in memory locations 417h and 418h. Use the output to figure out which bit represents what part of the shift state.
  • Chapter 7, Exercise 2: Write another version of the Video Easel program that uses the keyboard instead of the mouse; however, make a pointer that resembles the mouse pointer using sprites.
  • Chapter 7, Exercise 3: Experiment with the mouse sensitivity until one inch on your mouse pad is equivalent to one inch on your computer screen.
  • Chapter 7, Exercise 4: See if you can figure out a technique to detect whether a joystick(s) is present that differs from the technique we implemented today.
  • Chapter 8, Exercise 1: Modify the fixed-point library to use a fixed-point number format that has 16 bits of whole part and 16 bits of decimal part.
  • Chapter 8, Exercise 2: Write a test program that creates two fixed-point numbers and then adds them together 10,000 times. Compare this to using floating-point numbers.
  • Chapter 8, Exercise 3: Compare the difference in speed between the C and in-line two versions of Fill_Double_Buffer().
  • Chapter 8, Exercise 4: Extra Credit (really hard): Try to figure out how to perform general binary division of any divisor using shifting.