From 6bfead54cc8282952703bae73d801dc7f2be231e Mon Sep 17 00:00:00 2001
From: Louis Pearson <opensource@louispearson.work>
Date: Sat, 6 Aug 2022 17:30:06 -0600
Subject: [PATCH] Allow movement between screens

---
 src/component.zig |  3 +++
 src/game.zig      | 51 ++++++++++++++++++++++++++++++++++++++---------
 src/main.zig      |  6 +++++-
 src/world.zig     |  9 +++++++++
 4 files changed, 59 insertions(+), 10 deletions(-)

diff --git a/src/component.zig b/src/component.zig
index a55f14d..2c7770e 100644
--- a/src/component.zig
+++ b/src/component.zig
@@ -23,6 +23,9 @@ pub const Pos = struct {
     pub fn getDirection(pos: Pos) Vec2f {
         return pos.pos - pos.last;
     }
+    pub fn getVelocity(pos: Pos) Vec2f {
+        return pos.pos - pos.last;
+    }
 };
 pub const Control = struct {
     controller: enum { player },
diff --git a/src/game.zig b/src/game.zig
index d174255..68e64c7 100644
--- a/src/game.zig
+++ b/src/game.zig
@@ -220,16 +220,44 @@ fn loadLevel(lvl: usize) !void {
     });
 }
 
-fn moveLevel(direction: enum { L, R, U, D }, lvl: usize) !void {
-    try loadLevel(lvl);
-    // var momentum = player.pos.pos - player.pos.last;
+fn moveLevel(direction: enum { L, R, U, D }) !void {
+    // TODO: Figure out the more principled way for checking boundaries
+    var velocity = player.pos.getVelocity();
     switch (direction) {
-        .L => player.pos.pos[0] = 156,
-        .R => player.pos.pos[0] = 4,
-        .U => player.pos.pos[1] = 156,
-        .D => player.pos.pos[1] = 4,
+        .L => {
+            const x = level.world_x - 1;
+            const y = level.world_y;
+            const lvl = db.findLevel(x, y) orelse return error.NoLevelLeft;
+
+            try loadLevel(lvl);
+            player.pos.pos[0] = 160 - @intToFloat(f32, @divFloor(player.sprite.size[0], 2));
+        },
+        .R => {
+            const x = level.world_x + 1;
+            const y = level.world_y;
+            const lvl = db.findLevel(x, y) orelse return error.NoLevelRight;
+
+            try loadLevel(lvl);
+            player.pos.pos[0] = @intToFloat(f32, @divFloor(player.sprite.size[0], 2));
+        },
+        .U => {
+            const x = level.world_x;
+            const y = level.world_y - 1;
+            const lvl = db.findLevel(x, y) orelse return error.NoLevelUp;
+
+            try loadLevel(lvl);
+            player.pos.pos[1] = 160;
+        },
+        .D => {
+            const x = level.world_x;
+            const y = level.world_y + 1;
+            const lvl = db.findLevel(x, y) orelse return error.NoLevelDown;
+
+            try loadLevel(lvl);
+            player.pos.pos[1] = @intToFloat(f32, player.sprite.size[1]);
+        },
     }
-    player.pos.last = player.pos.pos;
+    player.pos.last = player.pos.pos - velocity;
 }
 
 pub fn start() !void {
@@ -341,7 +369,12 @@ pub fn update(time: usize) !State {
     physicsProcess(1, &player.pos, &player.physics);
     try manipulationProcess(&player.pos, &player.control);
     controlProcess(time, &player.pos, &player.control, &player.physics, &player.kinematic);
-    if (player.pos.pos[0] > 160 - 4) try moveLevel(.R, 1);
+
+    if (player.pos.pos[0] > 160 - 4) try moveLevel(.R);
+    if (player.pos.pos[0] < 4) try moveLevel(.L);
+    if (player.pos.pos[1] > 160 - 4) try moveLevel(.D);
+    if (player.pos.pos[1] < 4) try moveLevel(.U);
+
     try kinematicProcess(1, &player.pos, &player.kinematic);
     controlAnimProcess(1, &player.sprite, &player.controlAnim, &player.control);
     try particles.update();
diff --git a/src/main.zig b/src/main.zig
index 3e1b650..68ddeff 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -33,7 +33,11 @@ export fn update() void {
             error.EndOfStream => showErr(@errorName(e)),
             error.OutOfMemory => showErr(@errorName(e)),
             error.InvalidLevel => showErr(@errorName(e)),
-                error.NullTiles => showErr(@errorName(e)),
+            error.NullTiles => showErr(@errorName(e)),
+            error.NoLevelDown => showErr(@errorName(e)),
+            error.NoLevelUp => showErr(@errorName(e)),
+            error.NoLevelLeft => showErr(@errorName(e)),
+            error.NoLevelRight => showErr(@errorName(e)),
         },
     };
     if (state != newState) {
diff --git a/src/world.zig b/src/world.zig
index ef272cc..6992628 100644
--- a/src/world.zig
+++ b/src/world.zig
@@ -504,6 +504,15 @@ pub const Database = struct {
 
         return level_info;
     }
+
+    pub fn findLevel(db: *Database, x: i8, y: i8) ?usize {
+        for (db.level_info) |level, i| {
+            if (level.x == x and level.y == y) {
+                return i;
+            }
+        }
+        return null;
+    }
 };
 
 // All levels in the game. If two rooms are next to each other, they