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| very basic bitmap animation |
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DuncanShine
Member #17,479
March 2020
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I have created two images that are supposed to be part of a character's animation cycle, and I want to rapidly switch between the two images, like a run cycle. However, just doing this makes the image change way too quickly, and adding a delay with Sleep() would slow down the whole program so i'm stuck as to how i would do it |
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Edgar Reynaldo
Major Reynaldo
May 2007
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The key is measuring time without delaying the program. A timer will work for this, as will al_wait_for_vsync, or simply al_get_time. Decide the duration of the animation in seconds, determine how many frames you have and then to get the current animation frame, use fmod. 1#include <allegro5/allegro.h>
2...
3const double FPS = 60.0;
4const double SPF = 1.0/FPS;
5
6ALLEGRO_EVENT_QUEUE* queue = al_create_event_queue();
7ALLEGRO_TIMER* timer = al_create_timer(SPF);
8if (!timer) {Fail();}
9al_register_event_source(queue , al_get_timer_event_source(timer));
10
11double duration = 2.0;/// 2 seconds for 2 frames
12int nframes = 2;
13double elapsed_time;
14
15al_start_timer(timer);
16
17/// In event loop
18while (!quit) {
19 if (redraw) {
20 al_clear_to_color(al_map_rgb(255,255,255));
21 int FRAME_NUM = (int)nframes*fmod(elapsed_time , duration)/duration;
22 al_draw_bitmap(bitmaps[FRAME_NUM] , 0 , 0);
23 al_flip_display();
24 redraw = false;
25 }
26
27 do {
28 ALLEGRO_EVENT ev;
29 al_wait_for_event(queue , &ev);
30 if (ev.type == ALLEGRO_EVENT_TIMER) {
31 elapsed_time += SPF;
32 redraw = true;
33 }
34 } while (!al_is_event_queue_empty(queue));
35};
36return 0;
37}
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Niunio
Member #1,975
March 2002
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[edit]I was distracted and Edgar send it before me, but I think mine is simpler.[/edit] Keep track about how many time the animation frame is on screen: 1 typedef struct {
2 int frame, cnt
3 } ANIMATION_STATE;
4
5 ANIMATION_STATE MySpriteState;
6
7...
8
9/* Initialization */
10 MySpriteState.frame = FIRST_FRAME_NDX; MySpriteState.cnt = 0;
11
12....
13/* At updating. */
14 if (++MySpriteState.cnt > MAX_TIME_FRAME) {
15 MySpriteState.cnt = 0;
16 if (++MySpriteState.frame >= NUM_FRAMES) MySpriteState.frame = FIRST_FRAME_NDX;
17 }
18...
----------------- |
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DuncanShine
Member #17,479
March 2020
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This all works, how would i modify it to happen when the character is moving in a specific direction? |
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Niunio
Member #1,975
March 2002
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Not sure what do you mean... ----------------- |
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DuncanShine
Member #17,479
March 2020
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well i've made it so that when you change direction, the character does the opposite animation but the problem is a huge delay between pressing the button and the character actually moving. |
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Niunio
Member #1,975
March 2002
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Without actual code is hard to say. Maybe you should take a look to the Allegro Vivace tutorial. ----------------- |
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