Implement vertical collision (#2)

Makefile

@@ -1,4 +1,4 @@
-OBJS = src/main.o src/player.o src/platforms.o
+OBJS = src/main.o src/player.o src/platforms.o src/rect.o
 LIBS=$(shell pkg-config gl sdl2 --libs)
 CFLAGS=-Wall -Werror -std=c11 $(shell pkg-config gl sdl2 --cflags)
 

src/main.c

@@ -39,7 +39,7 @@ int main(int argc, char *argv[])
         goto sdl_create_renderer_fail;
     }
 
-    struct player *player = create_player(0.0f, GROUND_LEVEL);
+    struct player *player = create_player(100.0f, 0.0f);
     if (player == NULL) {
         perror("Could not create player");
         exit_code = -1;
@@ -49,7 +49,27 @@ int main(int argc, char *argv[])
     const struct rect_t platforms_rects[] = {
         { .x = 0.0f,
           .y = GROUND_LEVEL + 50.0f,
-          .w = SCREEN_WIDTH,
+          .w = 50.0f,
+          .h = 50.0f },
+        { .x = 150.0f,
+          .y = GROUND_LEVEL + 50.0f,
+          .w = SCREEN_WIDTH - 150.0f,
+          .h = 50.0f },
+        { .x = 0.0f,
+          .y = GROUND_LEVEL + 100.0f,
+          .w = 50.0f,
+          .h = 50.0f },
+        { .x = 150.0f,
+          .y = GROUND_LEVEL + 100.0f,
+          .w = 50.0f,
+          .h = 50.0f },
+        { .x = 0.0f,
+          .y = GROUND_LEVEL + 150.0f,
+          .w = 50.0f,
+          .h = 50.0f },
+        { .x = 150.0f,
+          .y = GROUND_LEVEL + 150.0f,
+          .w = 50.0f,
           .h = 50.0f }
     };
     struct platforms_t *platforms = create_platforms(
@@ -72,6 +92,13 @@ int main(int argc, char *argv[])
             case SDL_QUIT:
                 quit = 1;
                 break;
+
+            case SDL_KEYDOWN:
+                switch (e.key.keysym.sym) {
+                case SDLK_SPACE:
+                    player_jump(player);
+                    break;
+                }
             }
 
         }
@@ -84,7 +111,7 @@ int main(int argc, char *argv[])
             player_stop(player);
         }
 
-        update_player(player, delay_ms);
+        update_player(player, platforms, delay_ms);
 
         SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
         SDL_RenderClear(renderer);

src/platforms.c

@@ -69,3 +69,18 @@ int render_platforms(const struct platforms_t *platforms,
 
     return 0;
 }
+
+int platforms_rect_object_collide(const struct platforms_t *platforms,
+                                  const struct rect_t *object)
+{
+    assert(platforms);
+    assert(object);
+
+    for (size_t i = 0; i < platforms->rects_size; ++i) {
+        if (rects_intersect(object, &platforms->rects[i])) {
+            return 1;
+        }
+    }
+
+    return 0;
+}

src/platforms.h

@@ -12,4 +12,7 @@ void destroy_platforms(struct platforms_t *platforms);
 int render_platforms(const struct platforms_t *platforms,
                      SDL_Renderer *renderer);
 
+int platforms_rect_object_collide(const struct platforms_t *platforms,
+                                  const struct rect_t *object);
+
 #endif  // PLATFORMS_H_

src/player.c

@@ -3,10 +3,12 @@
 #include <SDL2/SDL.h>
 
 #include "./player.h"
+#include "./platforms.h"
 
 #define PLAYER_WIDTH 50.0f
 #define PLAYER_HEIGHT 50.0f
 #define PLAYER_SPEED 500.0f
+#define PLAYER_GRAVITY 1500.0f
 
 struct player {
     float x, y;
@@ -54,12 +56,36 @@ int render_player(const struct player * player,
     return 0;
 }
 
-void update_player(struct player * player, int delta_time)
+void update_player(struct player * player,
+                   const struct platforms_t *platforms,
+                   int delta_time)
 {
     float d = delta_time / 1000.0;
 
-    player->x += player->dx * d;
-    player->y += player->dy * d;
+    float dx = player->dx;
+    float dy = player->dy + PLAYER_GRAVITY * d;
+
+    float x = player->x + dx * d;
+    float y = fmod(player->y + dy * d, 600.0f);
+
+    struct rect_t player_object = {
+        .x = x,
+        .y = y,
+        .w = PLAYER_WIDTH,
+        .h = PLAYER_HEIGHT
+    };
+
+    /* TODO: Implement collision for the left/right sides */
+    if (platforms_rect_object_collide(platforms, &player_object)) {
+        dy = -player->dy * 0.75;
+        x = player->x + dx * d;
+        y = fmod(player->y + dy * d, 600.0f);
+    }
+
+    player->dx = dx;
+    player->dy = dy;
+    player->x = x;
+    player->y = y;
 }
 
 void player_move_left(struct player *player)
@@ -76,3 +102,8 @@ void player_stop(struct player *player)
 {
     player->dx = 0.0f;
 }
+
+void player_jump(struct player *player)
+{
+    player->dy = -500.0f;
+}

src/player.h

@@ -2,6 +2,7 @@
 #define PLAYER_H_
 
 struct player;
+struct platforms_t;
 struct SDL_Renderer;
 
 struct player *create_player(float x, float y);
@@ -9,10 +10,13 @@ void destroy_player(struct player * player);
 
 int render_player(const struct player * player,
                   SDL_Renderer *renderer);
-void update_player(struct player * player, int delta_time);
+void update_player(struct player * player,
+                   const struct platforms_t *platforms,
+                   int delta_time);
 
 void player_move_left(struct player *player);
 void player_move_right(struct player *player);
 void player_stop(struct player *player);
+void player_jump(struct player *player);
 
 #endif  // PLAYER_H_

src/rect.c

@@ -0,0 +1,12 @@
+#include <math.h>
+#include "./rect.h"
+
+int rects_intersect(const struct rect_t *rect1,
+                    const struct rect_t *rect2)
+{
+    float x1 = fmax(rect1->x, rect2->x);
+    float y1 = fmax(rect1->y, rect2->y);
+    float x2 = fmin(rect1->x + rect1->w, rect2->x + rect2->w);
+    float y2 = fmin(rect1->y + rect1->h, rect2->y + rect2->h);
+    return x1 <= x2 && y1 <= y2;
+}

src/rect.h

@@ -5,5 +5,7 @@ struct rect_t {
     float x, y, w, h;
 };
 
+int rects_intersect(const struct rect_t *rect1,
+                    const struct rect_t *rect2);
 
 #endif  // RECT_H_