From 1478084ab6d6c4d96cb685247a3b03781904b7fa Mon Sep 17 00:00:00 2001
From: Rokas Puzonas <rokas.puz@gmail.com>
Date: Wed, 19 Jul 2023 21:27:00 +0300
Subject: [PATCH] account for when user comes back to page after a long time
 for wasm

---
 Makefile     |  7 ++++++-
 src/main.cpp | 21 ++++++++++++++++-----
 2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index 92f6756..8cd6d99 100644
--- a/Makefile
+++ b/Makefile
@@ -30,6 +30,7 @@ ifeq ($(OS), Windows_NT)
 	RM := -del /q
 	COPY = -robocopy "$1" "$2" $3
 	EXT = .exe
+	MOVE := move
 
 	OS_NAME := windows
 	LINKER_FLAGS += -Wl,--allow-multiple-definition -pthread -lopengl32
@@ -40,6 +41,7 @@ else
 	MKDIR := mkdir -p
 	RM := rm -rf
 	COPY = cp $1/$3 $2
+	MOVE := mv
 
 	OS_NAME := linux
 	LINKER_FLAGS += -lGL -lm -lpthread -ldl -lrt -lX11
@@ -108,6 +110,9 @@ emsdk: submodules
 # Link the program and create the executable
 $(MAIN_TARGET): $(OBJECTS)
 	$(CXX) $(OBJECTS) -o $(MAIN_TARGET) $(LINKER_FLAGS) -D$(RAYLIB_PLATFORM)
+ifeq ($(PLATFORM), web)
+	$(MOVE) $(MAIN_TARGET) $(BUILD_DIR)/index.html
+endif
 
 # Compile objects to the build directory
 $(BUILD_DIR)/%.o: src/%.cpp Makefile
@@ -117,7 +122,7 @@ $(BUILD_DIR)/%.o: src/%.cpp Makefile
 # Run the executable
 run:
 ifeq ($(PLATFORM), web)
-	serve $(BUILD_DIR) $(ARGS)
+	python -m http.server 8080 -d $(BUILD_DIR)
 else
 	$(MAIN_TARGET) $(ARGS)
 endif
diff --git a/src/main.cpp b/src/main.cpp
index 8f8d598..f28051a 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -11,6 +11,9 @@
 #include "boid-playground.hpp"
 #include "raycast.cpp"
 
+#define FRAMERATE 60
+#define TIME_PER_FRAME (1.0/FRAMERATE)
+
 static World g_world;
 static Visuals g_visuals;
 
@@ -186,9 +189,7 @@ static int get_boids_in_view_cone(Boid **boids_in_view, Boid *boid, float view_r
 	return count;
 }
 
-static void world_update(World *world) {
-	float dt = GetFrameTime();
-
+static void world_update(World *world, float dt) {
 	for (int i = 0; i < world->boids.size(); i++) {
 		Boid *boid = &world->boids[i];
 		Vector2 acc = { 1, 0 };
@@ -327,7 +328,17 @@ void UpdateDrawFrame() {
 	// TODO: Show this on screen
 	// LogTrace("%d", count_out_of_bounds_boids(&world));
 
-	world_update(&g_world);
+	float dt = GetFrameTime();
+
+#ifdef PLATFORM_WEB
+	// If user goes to another tab and comes back, the time that the user was gone needs to be ignored.
+	// So boids wouldn't tunnel through walls and do other shenanigans.
+	if (dt <= 5*TIME_PER_FRAME) {
+		world_update(&g_world, dt);
+	}
+#else
+	world_update(&g_world, dt);
+#endif
 
 	// Draw
 	BeginDrawing();
@@ -371,7 +382,7 @@ int main() {
 #ifdef PLATFORM_WEB
 	emscripten_set_main_loop(UpdateDrawFrame, 0, 1);
 #else
-	SetTargetFPS(60);
+	SetTargetFPS(FRAMERATE);
 	while (!window.ShouldClose()) {
 		UpdateDrawFrame();
 	}