gravity is out of their mind

Implements: https://todo.sr.ht/~kikoodx/jtmm2/6

CMakeLists.txt

@@ -25,6 +25,7 @@ set(ASSETS
 	res/burn.kble
 	res/bounce.kble
 	res/worm.kble
+	res/shake.kble
 	res/fonts/dina.png
 )
 

inc/conf.h

@@ -18,3 +18,4 @@
 #define BURN_DEATH          3
 #define BOUNCE_SPEED        -2.0f
 #define DRAW_OFF_X          -2
+#define GRAVS_MARGIN        0

inc/player.h

@@ -4,7 +4,7 @@
 enum AirState { AS_NEUTRAL, AS_RISING, AS_BREAKING };
 
 struct Player {
-	struct Vec pos;
+	struct Vec pos, gravity;
 	struct VecF spd, rem;
 	enum AirState air_state;
 	int jump_buffer, jump_grace, burn, bouncing;

inc/tile.h

@@ -9,5 +9,9 @@ enum Tile {
 	TILE_EXIT,
 	TILE_BURN,
 	TILE_BOUNCER,
+	TILE_GRAV_D,
+	TILE_GRAV_U,
+	TILE_GRAV_R,
+	TILE_GRAV_L,
 	TILE_OOB,
 };

src/level.c

@@ -11,13 +11,11 @@
 static struct Level level;
 extern bopti_image_t bimg_tileset;
 
-extern struct LevelBin kble_test, kble_burn, kble_bounce, kble_worm;
+extern struct LevelBin kble_test, kble_burn, kble_bounce, kble_worm, kble_shake;
 static const struct LevelBinNamed levels[] = {
-    {&kble_test, "gentle introduction"},
-    {&kble_burn, "these are rare"},
-    {&kble_bounce, "deceptive road"},
-    {&kble_worm, "under your skin"},
-    {NULL, NULL}};
+    {&kble_test, "gentle introduction"},    {&kble_burn, "these are rare"},
+    {&kble_bounce, "deceptive road"},       {&kble_worm, "under your skin"},
+    {&kble_shake, "breaking into reality"}, {NULL, NULL}};
 
 static void level_free(void);
 

src/player.c

@@ -19,6 +19,8 @@ player_spawn(struct Player *p)
 	struct Vec pos = level_find(TILE_SPAWN);
 	p->pos.x = pos.x * TILE_SIZE + (TILE_SIZE - PLAYER_WIDTH) / 2;
 	p->pos.y = pos.y * TILE_SIZE + TILE_SIZE - PLAYER_HEIGHT;
+	p->gravity.x = 0;
+	p->gravity.y = 1;
 	reset_speed(p, 1, 1);
 	p->air_state = AS_NEUTRAL;
 	p->jump_buffer = 0;
@@ -29,7 +31,8 @@ player_spawn(struct Player *p)
 void
 player_update(struct Player *p)
 {
-	const int on_ground = collide_solid(p->pos.x, p->pos.y + 1);
+	const int on_ground =
+	    collide_solid(p->pos.x + p->gravity.x, p->pos.y + p->gravity.y);
 	const int k_left = input_down(K_LEFT);
 	const int k_right = input_down(K_RIGHT);
 	// const int k_up = input_down(K_UP);
@@ -38,18 +41,27 @@ player_update(struct Player *p)
 	const int kp_jump = input_pressed(K_JUMP);
 	const int kp_polarity = input_pressed(K_POLARITY);
 	const int dir_x = k_right - k_left;
+	const struct Vec rem_gravity = p->gravity;
+	float spd_x, spd_y;
+
+	/* speed transformation */
+	spd_x = p->spd.x;
+	spd_y = p->spd.y * p->gravity.y;
+	if (p->gravity.x) {
+		spd_x = p->spd.y;
+		spd_y = p->spd.x * p->gravity.x;
+	}
 
 	/* polarity swap */
 	if (kp_polarity) polarity_invert();
 
 	/* horizontal friction & acceleration */
-	p->spd.x *= on_ground ? (1 - GROUND_FRICTION) : (1 - AIR_FRICTION);
-	p->spd.x +=
-	    dir_x * (on_ground ? GROUND_ACCELERATION : AIR_ACCELERATION);
+	spd_x *= on_ground ? (1 - GROUND_FRICTION) : (1 - AIR_FRICTION);
+	spd_x += dir_x * (on_ground ? GROUND_ACCELERATION : AIR_ACCELERATION);
 
 	/* air resistance & gravity */
-	p->spd.y *= (1 - AIR_RESISTANCE);
-	p->spd.y +=
+	spd_y *= (1 - AIR_RESISTANCE);
+	spd_y +=
 	    (p->air_state == AS_BREAKING) ? (GRAVITY * JUMP_BREAK) : (GRAVITY);
 
 	/* air state machine */
@@ -59,7 +71,7 @@ player_update(struct Player *p)
 		if (!k_jump) p->air_state = AS_BREAKING;
 		/* fallthrough */
 	case AS_BREAKING:
-		if (p->spd.y > 0) p->air_state = AS_NEUTRAL;
+		if (spd_y > 0) p->air_state = AS_NEUTRAL;
 		break;
 	case AS_NEUTRAL:
 	default:
@@ -78,7 +90,7 @@ player_update(struct Player *p)
 		p->jump_grace--;
 	/* jump */
 	if (p->jump_grace && p->jump_buffer && k_jump) {
-		p->spd.y = JUMP_SPEED;
+		spd_y = JUMP_SPEED;
 		p->air_state = AS_RISING;
 		p->jump_buffer = 0;
 		p->jump_grace = 0;
@@ -87,7 +99,7 @@ player_update(struct Player *p)
 	/* bounce */
 	if (collide(p->pos.x, p->pos.y, TILE_BOUNCER)) {
 		if (!p->bouncing) {
-			p->spd.y = -absf(p->spd.y) + BOUNCE_SPEED;
+			spd_y = -absf(spd_y) + BOUNCE_SPEED;
 			p->bouncing = 1;
 		}
 	} else {
@@ -96,15 +108,49 @@ player_update(struct Player *p)
 
 	/* burn and death */
 	if (collide(p->pos.x, p->pos.y, TILE_BURN)) {
-		if (++p->burn >= BURN_DEATH) level_reload();
+		if (++p->burn >= BURN_DEATH) {
+			level_reload();
+			return;
+		}
 	} else if (p->burn) {
 		p->burn--;
 	}
 
 	/* next level */
-	if (collide(p->pos.x, p->pos.y, TILE_EXIT)) level_next();
+	if (collide(p->pos.x, p->pos.y, TILE_EXIT)) {
+		level_next();
+		return;
+	}
+
+	/* speed transformation */
+	if (rem_gravity.y) {
+		p->spd.x = spd_x;
+		p->spd.y = spd_y * p->gravity.y;
+	}
+	if (rem_gravity.x) {
+		p->spd.y = spd_x;
+		p->spd.x = spd_y * p->gravity.x;
+	}
 
 	player_move(p, update_rem(p));
+
+	/* gravity modifiers */
+	if (collide_margin(p->pos.x, p->pos.y, TILE_GRAV_D, GRAVS_MARGIN)) {
+		p->gravity.x = 0;
+		p->gravity.y = 1;
+	}
+	if (collide_margin(p->pos.x, p->pos.y, TILE_GRAV_U, GRAVS_MARGIN)) {
+		p->gravity.x = 0;
+		p->gravity.y = -1;
+	}
+	if (collide_margin(p->pos.x, p->pos.y, TILE_GRAV_R, GRAVS_MARGIN)) {
+		p->gravity.x = 1;
+		p->gravity.y = 0;
+	}
+	if (collide_margin(p->pos.x, p->pos.y, TILE_GRAV_L, GRAVS_MARGIN)) {
+		p->gravity.x = -1;
+		p->gravity.y = 0;
+	}
 }
 
 void