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/*
* Example program for the Allegro library, by Shawn Hargreaves.
*
* This program demonstrates how to use an offscreen part of the
* video memory to store source graphics for a hardware accelerated
* graphics driver.
*/
#include "allegro.h"
#define MAX_IMAGES 256
/* structure to hold the current position and velocity of an image */
typedef struct IMAGE
{
float x, y;
float dx, dy;
} IMAGE;
/* initialises an image structure to a random position and velocity */
void init_image(IMAGE *image)
{
image->x = (float)(rand() % 704);
image->y = (float)(rand() % 568);
image->dx = (float)((rand() % 255) - 127) / 32.0;
image->dy = (float)((rand() % 255) - 127) / 32.0;
}
/* called once per frame to bounce an image around the screen */
void update_image(IMAGE *image)
{
image->x += image->dx;
image->y += image->dy;
if (((image->x < 0) && (image->dx < 0)) ||
((image->x > 703) && (image->dx > 0)))
image->dx *= -1;
if (((image->y < 0) && (image->dy < 0)) ||
((image->y > 567) && (image->dy > 0)))
image->dy *= -1;
}
int main(int argc, char *argv[])
{
char buf[256];
PALETTE pal;
BITMAP *image;
BITMAP *page[2];
BITMAP *vimage;
IMAGE images[MAX_IMAGES];
int num_images = 4;
int page_num = 1;
int done = FALSE;
int i;
allegro_init();
install_keyboard();
install_timer();
/* very high res video mode */
if (set_gfx_mode(GFX_AUTODETECT, 1024, 768, 0, 0) != 0) {
set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
allegro_message("Error setting graphics mode\n%s\n", allegro_error);
return 1;
}
/* read in the source graphic */
replace_filename(buf, argv[0], "mysha.pcx", sizeof(buf));
image = load_bitmap(buf, pal);
if (!image) {
set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
allegro_message("Error reading %s!\n", buf);
return 1;
}
set_palette(pal);
/* initialise the images to random positions */
for (i=0; i<MAX_IMAGES; i++)
init_image(images+i);
/* create two video memory bitmaps for page flipping */
page[0] = create_video_bitmap(SCREEN_W, SCREEN_H);
page[1] = create_video_bitmap(SCREEN_W, SCREEN_H);
/* create a video memory bitmap to store our picture */
vimage = create_video_bitmap(image->w, image->h);
if ((!page[0]) || (!page[1]) || (!vimage)) {
set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
allegro_message("Not enough video memory (need two 1024x768 pages and a 320x200 image)\n");
return 1;
}
/* copy the picture into offscreen video memory */
blit(image, vimage, 0, 0, 0, 0, image->w, image->h);
while (!done) {
acquire_bitmap(page[page_num]);
/* clear the screen */
clear_bitmap(page[page_num]);
/* draw onto it */
for (i=0; i<num_images; i++)
blit(vimage, page[page_num], 0, 0, images[i].x, images[i].y, vimage->w, vimage->h);
text_mode(-1);
textprintf(page[page_num], font, 0, 0, 255, "Images: %d (arrow keys to change)", num_images);
/* tell the user which functions are being done in hardware */
if (gfx_capabilities & GFX_HW_FILL)
textout(page[page_num], font, "Clear: hardware accelerated", 0, 16, 255);
else
textout(page[page_num], font, "Clear: software (urgh, this is not good!)", 0, 16, 255);
if (gfx_capabilities & GFX_HW_VRAM_BLIT)
textout(page[page_num], font, "Blit: hardware accelerated", 0, 32, 255);
else
textout(page[page_num], font, "Blit: software (urgh, this program will run too sloooooowly without hardware acceleration!)", 0, 32, 255);
release_bitmap(page[page_num]);
/* page flip */
show_video_bitmap(page[page_num]);
page_num = 1-page_num;
/* deal with keyboard input */
while (keypressed()) {
switch (readkey()>>8) {
case KEY_UP:
case KEY_RIGHT:
if (num_images < MAX_IMAGES)
num_images++;
break;
case KEY_DOWN:
case KEY_LEFT:
if (num_images > 0)
num_images--;
break;
case KEY_ESC:
done = TRUE;
break;
}
}
/* bounce the images around the screen */
for (i=0; i<num_images; i++)
update_image(images+i);
}
destroy_bitmap(image);
destroy_bitmap(vimage);
destroy_bitmap(page[0]);
destroy_bitmap(page[1]);
return 0;
}
END_OF_MAIN();
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