This tutorial will just play a simple animation over and over again, regarless of what key you are pressing, or in what direction you are moving. It will keep playing even if you don't press anything.
To acheive different effects, you could create different variables to hold the states as to what direction the user is heading, or whether the user is even moving at all!
#include <allegro.h> // You must include the Allegro Header file
/* Timer stuff */
volatile long speed_counter = 0; // A long integer which will store the value of the
// speed counter.
void increment_speed_counter() // A function to increment the speed counter
speed_counter++; // This will just increment the speed counter by one.
END_OF_FUNCTION(increment_speed_counter); // Make sure you tell it that it's the end of the
int main(int argc, char *argv)
allegro_init(); // Initialize Allegro
install_keyboard(); // Initialize keyboard routines
install_timer(); // Initialize the timer routines
LOCK_VARIABLE(speed_counter); // Used to set the timer which regulates the game's
LOCK_FUNCTION(increment_speed_counter); // speed.
install_int_ex(increment_speed_counter, BPS_TO_TIMER(60)); // Set our BPS
set_color_depth(16); // Set the color depth
set_gfx_mode(GFX_AUTODETECT, 640,480,0,0); // Change our graphics mode to 640x480
BITMAP *frame2 = load_bitmap("frame2.bmp", NULL);
BITMAP *frame3 = load_bitmap("frame3.bmp", NULL);
This code is the same as in the previous lesson. Create the buffer, and location holders for the position of the frames.
Declare some integers for later use */
int my_pic_x = 0;// Holds our pictures X coorinate
int my_pic_y = 0;// Holds our picture's Y coordinate
This code stays the same as the previous lessons
while(speed_counter > 0)
if(key[KEY_RIGHT]) // If the user hits the right key, change the picture's X coordinate
my_pic_x ++; // Moving right so up the X coordinate by 1
else if(key[KEY_LEFT]) // Ditto' - only for left key
my_pic_x --; // Moving left, so lower the X coordinate by 1
else if(key[KEY_UP]) // If the user hits the up key, change the picture's Y coordinate
my_pic_y --; // Moving up, so lower the Y coordinate by 1
else if(key[KEY_DOWN]) // Ditto' - only for down
my_pic_y ++; // Moving down, so up the Y coordinate by 1
Here we test to see if the frame counter is over 4 seconds. If it is, we set it back to zero in order to restart the animation. We are only testing for four seconds because we are only drawing 1 frame a second, and we're drawing a total of four frames. The next big chunk of explanation will clear up any confusion regarding this.
frame_counter = 0;
This doesn't really need explanation. This is the closing bracket for one statment, and the screen aquiring function in the beginning of the drawing section of the code.
Here is where things get a little tricky. There are multiple ways to do this, but I'll show you the one with the least lines of code.
As you read earlier, when frame_counter == 60, one second
has passed, so we will draw each frame at one second.
if(frame_counter < 60) // Less than a full second
draw_sprite(buffer, frame1, my_pic_x, my_pic_y); // Draw the first frame
else if(frame_counter >= 60 && frame_counter < 120) // Between 1 and 2 seconds
draw_sprite(buffer, frame2, my_pic_x, my_pic_y); // Draw the second frame
else if(frame_counter >= 120 && frame_counter < 180) // If we are between 2 and 3 seconds
draw_sprite(buffer, frame1, my_pic_x, my_pic_y); // Draw the first frame again,
// to acheive better effect
else // If we are over 3 seconds
draw_sprite(buffer, frame3, my_pic_x, my_pic_y); // Draw the last frame.
End of the drawing portion -- same as the previous lesson's
Don't forget to destroy all the bitmaps we created, and do the rest of the deinitializing.
destroy_bitmap(frame2);//Release the bitmap data
destroy_bitmap(frame3);//Release the bitmap data
destroy_bitmap(buffer);//Release the bitmap data
return 0; // Exit with no errors
END_OF_MAIN() // This must be called right after the closing bracket of your MAIN function.
// It is Allegro specific.
That's it. That's as simple you can get with animation. Feel free to play around with the timing, and the framing. Add in more frames if you would like. Create integers to allow the animation to play ONLY when a key is being pressed by setting a value to TRUE, when a key is pressed, and FALSE when no keys are pressed. Experiment to get exactly what you want.
Download Lesson 7 Source
Continue to Lesson 8
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