01: Add animation switching

01-introduction/README.md

@@ -0,0 +1,9 @@
+<p align="center">
+    <img src=".imgs/showcase.png" width="300" />
+</p>
+
+# Introduction
+
+First code I ever wrote for SDL. It contains some basic functionality for importing textures, player movement, and animations/animation switching
+
+

01-introduction/src/main.c

@@ -3,15 +3,16 @@
 #include <SDL2/SDL_image.h>
 #include "structs.h"
 
-const int SCREEN_WIDTH = 640; 
+const int SCREEN_WIDTH = 1000; 
 const int SCREEN_HEIGHT = 480;
-const Uint32 WINDOW_FLAGS = SDL_WINDOW_SHOWN | SDL_WINDOW_OPENGL | SDL_WINDOW_BORDERLESS; 
+const Uint32 WINDOW_FLAGS = SDL_WINDOW_SHOWN | SDL_WINDOW_OPENGL; 
 const Uint32 RENDERER_FLAGS = SDL_RENDERER_ACCELERATED;
 int GAME_RUNNING = 1;
 struct game game; 
-int movement_speed = 5;
-int animation_frames = 100;
-int frames = 0;
+int movement_speed = 10;
+int gravity = 8;
+double delta_time; 
+double last_frame;
 
 void prepare_scene(void) {
     SDL_SetRenderDrawColor(game.renderer, 96, 128, 255, 255);
@@ -22,10 +23,6 @@ void key(SDL_KeyboardEvent *event) {
     if (event->repeat != 0)
         return;   
 
-    if (event->keysym.scancode == SDL_SCANCODE_W)
-        game.up = !game.up;
-    if (event->keysym.scancode == SDL_SCANCODE_S)
-        game.down = !game.down;
     if (event->keysym.scancode == SDL_SCANCODE_A)
         game.left = !game.left;
     if (event->keysym.scancode == SDL_SCANCODE_D)
@@ -63,7 +60,7 @@ SDL_Texture *load_texture(const char *path) {
     return texture;
 }
 
-struct object *create_object(const char *texture_path, int x, int y, int scale, int resolution) {
+struct object *create_object(SDL_Texture *texture, int x, int y, int scale, int resolution) {
     struct object *object = (struct object *) calloc(1, sizeof(struct object));
 
     if (object == NULL) {
@@ -71,26 +68,22 @@ struct object *create_object(const char *texture_path, int x, int y, int scale,
         return NULL;
     }
 
-    object->texture = load_texture(texture_path);
-
-    if (object->texture == NULL) {
-        fprintf(stderr, "Error: loading texture into new object\n");
-        return NULL;
-    }
-
+    object->texture = texture;
+    object->resolution = resolution;
+    object->animation_speed = 15;
+    object->scale = scale;
     object->x = x; 
     object->y = y;
-    object->scale = scale;
-    object->resolution = resolution;
 
     return object;
 }
 
 void draw_object(struct object *object) {
+    int texture_width; 
     SDL_Rect src;
     SDL_Rect dest;
 
-    src.x = object->state * object->resolution;
+    src.x = object->animation_slide * object->resolution;
     src.y = 0;
 
     src.w = object->resolution;
@@ -101,7 +94,17 @@ void draw_object(struct object *object) {
     dest.w = object->resolution * object->scale;
     dest.h = object->resolution * object->scale;
 
-    SDL_RenderCopy(game.renderer, object->texture, &src, &dest);
+    SDL_RenderCopyEx(game.renderer, object->texture, &src, &dest, 0, NULL, object->flip);
+
+    // update animation slide
+    SDL_QueryTexture(object->texture, NULL, NULL, &texture_width, NULL);
+
+    object->animation_clock += object->animation_speed*(delta_time/1000);
+
+    if (object->animation_clock >= 1) {
+        object->animation_clock = 0;    
+        object->animation_slide = (object->animation_slide+1) % (texture_width / object->resolution); // clock arithmetic: jump back to first animation slide 
+    }
 }
 
 void present_scene(void) {
@@ -128,24 +131,40 @@ int main(int argc, char *argv[]) {
         return -1;
     }
 
-    struct object *player = create_object("assets/player.png", SCREEN_WIDTH/2, SCREEN_HEIGHT/2, 3, 48);
+    // load player animations 
+    SDL_Texture *idle_animation = load_texture("assets/player/idle.png");
+    SDL_Texture *run_animation = load_texture("assets/player/run.png");
+
+    struct object *player = create_object(idle_animation, SCREEN_WIDTH/2, 0, 4, 48);
 
     // game loop
     while (GAME_RUNNING) {
-        frames++;
+        double current_frame = SDL_GetTicks();
+        delta_time = current_frame - last_frame;
+        last_frame = current_frame;
+
         prepare_scene();
         handle_input(); 
 
-        if (game.up)
-            player->y -= movement_speed; 
-        if (game.down)
-            player->y += movement_speed;
-        if (game.left) 
+        if (game.left) {
             player->x -= movement_speed; 
-        if (game.right) 
+            player->flip = SDL_FLIP_HORIZONTAL;
+            player->texture = run_animation;
+        }
+        if (game.right) {
             player->x += movement_speed;
+            player->flip = SDL_FLIP_NONE;
+            player->texture = run_animation;
+        }
+        if (!game.right && !game.left) {
+            player->texture = idle_animation;
+        }
 
-        player->state = ((frames % animation_frames)/5) % 10;
+        player->y += gravity;
+
+        if (player->y > SCREEN_HEIGHT-(player->resolution*player->scale)) {
+            player->y = SCREEN_HEIGHT-(player->resolution*player->scale);
+        }
 
         draw_object(player);
 

01-introduction/src/structs.h

@@ -7,22 +7,30 @@ struct game {
     SDL_Window *window; 
     SDL_Renderer *renderer;
 
-    int up; 
-    int down; 
     int left; 
     int right;
 };
 
+struct animation {
+    SDL_Texture *tilemap;   
+    int resolution;
+
+    int skippable;
+};
+
 struct object {
-    SDL_Texture *texture; 
-    int resolution; // of the texture/each tiles
+    SDL_Texture *texture;
+    int resolution;                 // of the texture/every tile
 
     int x; 
     int y;
     int scale;
+    Uint32 flip;
 
     // animation 
-    int state;
+    double animation_clock;         // everytime it reaches 1, the texture switches to the next slide
+    double animation_speed;         // how fast will the clock reach 1 with respect to delta_time
+    int animation_slide;            // the current slide of the animation
 };
 
 #endif 

README

@@ -1,4 +0,0 @@
-SDL Playground 
-==============
-
-My little playground for SDL.

README.md

@@ -0,0 +1,11 @@
+<p align="center">
+    <img src=".imgs/icon.png" width="200"/>
+</p>
+
+# SDL Playground 
+
+My little playground for SDL.
+
+## License
+
+The code is licensed under the GPL-3.0 license. See the `LICENSE` file for more information