Figure 6.5 A single sprite is flipped both vertically and horizontally

Figure 8.7

Figure 8.8

The tank sprite (courtesy of Ari Feldman) rotated in 16 directions.

#include

#include

#define WHITE makecol(255,255,255)

int main(void)

{

int x, y;

float angle = 0;

//initialize program

allegro init();

install keyboard();

set color depth(32);

set gfx mode(GFX AUTODETECT WINDOWED, 640, 480, 0, 0);

textout ex(screen, font, "Rotate: LEFT / RIGHT arrow keys",

0, 0, WHITE, 0);

//load tank sprite

BITMAP *tank = load bitmap("tank.bmp", NULL);

//calculate center of screen

x = SCREEN W/2 - tank->w/2;

y = SCREEN H/2 - tank->h/2;

//draw tank at starting location

rotate sprite(screen, tank, x, y, 0);

//main loop

while(!key[KEY ESC])

{

//wait for keypress

if (keypressed())

{

//left arrow rotates left

if (key[KEY LEFT])

{

angle -= 0.1;

if (angle < 0) angle = 256;

rotate sprite(screen, tank, x, y, itofix(angle));

}

//right arrow rotates right

if (key[KEY RIGHT])

{

angle þ= 0.1;

if (angle > 256) angle = 0;

rotate sprite(screen, tank, x, y, itofix(angle));

}

Basic Sprite Handling 285

//display angle

textprintf ex(screen,font,0,10,WHITE,0,"Angle = %f", angle);

}

}

allegro exit();

return 0;

}

END OF MAIN()

Additional Rotation Functions

The preceding function rotates and also flips the image vertically. To flip

horizontally, add itofix(128) to the angle. To flip in both directions, use

rotate sprite() and add itofix(128) to its angle.

The preceding function rotates an image and scales (stretches to fit) the image at

the same time.

void rotate scaled sprite v flip(BITMAP *bmp, BITMAP *sprite,

int x, int y, fixed angle, fixed scale)

The preceding function rotates the image while also scaling and flipping it

vertically, simply combining the functionality of the previous two functions.