Fix loop to be more accuratly timed, and added custom ruby libs inclusion setup

.gitignore

@@ -3,4 +3,6 @@
 build/*
 bin/*
 
-.clangd
+.clangd
+
+include/binding/ruby_compiled.h

Makefile

@@ -14,6 +14,7 @@ CXX := $(CCACHE) clang++
 CC := $(CCACHE) clang
 
 # ---------------- SDL3 ----------------
+
 SDL_CFLAGS := $(shell pkg-config --cflags sdl3 sdl3-ttf sdl3-image)
 SDL_LIBS_DEBUG := $(shell pkg-config --libs sdl3 sdl3-ttf sdl3-image)
 SDL_LIBS_RELEASE := $(shell pkg-config --libs sdl3 sdl3-ttf sdl3-image)
@@ -42,9 +43,11 @@ PCH_CFLAGS_RELEASE := $(CFLAGS_RELEASE) -x c++-header
 
 LIBS := ./libs/mruby/build/host/lib/libmruby.a
 
+MGEM_DIR := ./libs/l_mgems
+
 # ---------------- SOURCES ----------------
 
-SRC := $(wildcard $(SRC_DIR)/*.cc) $(wildcard $(SRC_DIR)/**/*.cc)
+SRC := $(shell find $(SRC_DIR) -name "*.cc")
 
 OBJ_DEBUG := $(patsubst $(SRC_DIR)/%.cc,$(OBJ_DIR)/debug/%.o,$(SRC))
 OBJ_RELEASE := $(patsubst $(SRC_DIR)/%.cc,$(OBJ_DIR)/release/%.o,$(SRC))
@@ -54,13 +57,13 @@ DEP_RELEASE := $(OBJ_RELEASE:.o=.d)
 
 # ---------------- TARGETS ----------------
 
-.PHONY: all debug release clean setup
+.PHONY: all debug release clean setup mgems
 
 all: debug
 
-debug: $(TARGET_DEBUG)
+debug: mgems $(TARGET_DEBUG)
 
-release: $(TARGET_RELEASE)
+release: mgems $(TARGET_RELEASE)
 
 # ---------------- CLANGD ----------------
 
@@ -68,6 +71,11 @@ setup: setup.rb
 	@echo "Setting up clangd configuration..."
 	ruby setup.rb
 
+# ---------------- MRB_MGEMS ----------------
+
+mgems:
+	$(MGEM_DIR)/compile.sh
+
 # ---------------- PCH ----------------
 
 $(PCH_DEBUG): $(INCLUDE_DIR)/pch.h

include/app/app.h

@@ -54,8 +54,7 @@ struct EImage : Element {
     Animation &animation = *animation_pool[animation_id];
     if (animation.frames.empty())
       return;
-
+    int frame_index = (int)((abs_time * animation.frame_rate) / 1e9) % animation.frames.size();
-    int frame_index = (int)((abs_time * animation.frame_rate) / 1000) % animation.frames.size();
     window.draw(animation.frames[frame_index], position, z, rotation, scale, alpha);
   }
 };
@@ -166,10 +165,10 @@ struct Scene {
   }
 
   void update_scene(uint64_t delta_time) {
-    if (!mrb_nil_p(update.proc)) {
+    if (mrb_nil_p(update.proc))
-      mrb_value dt_val = mrb_int_value(Ruby::mrb, delta_time);
+      return;
-      update.call(1, &dt_val);
+    mrb_value dt_val = mrb_float_value(Ruby::mrb, delta_time / 1e9);
-    }
+    update.call(1, &dt_val);
   }
 
   void click(Vec2<float> position) {
@@ -234,7 +233,7 @@ struct App {
   }
 
   void loop() {
-    const uint64_t target_ms = 1000 / 60;
+    const uint64_t TARGET_NS = 1e9 / 60;
 
     uint64_t time_a = window.get_time();
     uint64_t time_b = window.get_time();
@@ -242,8 +241,13 @@ struct App {
     while (running) {
       time_a = window.get_time();
       uint64_t frame_time = time_a - time_b;
-      if (frame_time <= target_ms)
+
-        usleep((target_ms - frame_time) * 1000);
+      if (frame_time <= TARGET_NS) {
+        struct timespec req;
+        req.tv_sec = 0;
+        req.tv_nsec = TARGET_NS - frame_time;
+        nanosleep(&req, nullptr);
+      }
 
       time_b = window.get_time();
 

include/binding/ruby.h

@@ -4,6 +4,8 @@
 #include "pch.h"
 #include "utils.h"
 
+#include "binding/ruby_compiled.h"
+
 #define DEF_SYM(name) inline mrb_sym sym_##name = mrb_intern_cstr(Ruby::mrb, #name);
 #define SYM(name) mrb_symbol_value(sym_##name)
 
@@ -83,7 +85,15 @@ struct Block {
 };
 
 inline void run_string(const char *code, size_t length) {
+  int ai = mrb_gc_arena_save(mrb);
   mrb_load_nstring(mrb, code, length);
+  mrb_gc_arena_restore(mrb, ai);
+}
+
+inline void load_mgems() {
+  int ai = mrb_gc_arena_save(mrb);
+  mrb_load_irep(mrb, mgems);
+  mrb_gc_arena_restore(mrb, ai);
 }
 }; // namespace Ruby
 

include/window/window.h

@@ -341,8 +341,8 @@ public:
 
   // Time
 
-  uint64_t get_time();   // returns the time in milliseconds since the window was created
+  uint64_t get_time();   // returns the time in nanoseconds since the window was created
-  uint64_t delta_time(); // returns the time in milliseconds since the last render call
+  uint64_t delta_time(); // returns the time in nanoseconds since the last render call
 
 private:
   // internal data and functions

libs/l_mgems/compile.sh

@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+
+set -e
+
+SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+OUTPUT_TMP=$(mktemp)
+OUTPUT="$SCRIPT_DIR/../../include/binding/ruby_compiled.h"
+
+if test "$1" = "clean"; then
+  rm -f "$OUTPUT"
+  exit 0
+fi
+
+trap 'rm -f "$OUTPUT_TMP"' EXIT
+
+mapfile -t FILES < <(find "$SCRIPT_DIR" -name "*.rb" | sort)
+
+LATEST_FILE_TIME=$(for file in "${FILES[@]}"; do
+  echo $(stat -c "%Y" "$file")
+done | sort -n | tail -1)
+
+OUTPUT_TIME=$(stat -c "%Y" "$OUTPUT" 2>/dev/null || echo 0)
+
+if test "$OUTPUT_TIME" -ge "$LATEST_FILE_TIME"; then
+  echo "mgems is up to date."
+  exit 0
+fi
+
+"$SCRIPT_DIR/../mruby/bin/mrbc" -o "$OUTPUT_TMP" "${FILES[@]}"
+
+{
+  echo "#ifndef MGEMS_H"
+  echo "#define MGEMS_H"
+  xxd -i -n mgems $OUTPUT_TMP \
+     | sed -e 's/^unsigned char /constexpr unsigned char /' \
+           -e 's/^unsigned int /constexpr unsigned int /'
+  echo "#endif"
+} > "$OUTPUT"
+
+echo "Compiled mgems!"

samples/button.rb

@@ -22,6 +22,7 @@ rect.on_click do
   rect.color = rect.color == 0xFF0000 ?
     0x00FF00 :
     0xFF0000
+  main_scene << text unless main_scene.elements.include?(text)
   text.params[:name] = text.params[:name] == "Me" ?
     "You" :
     "Me"
@@ -30,35 +31,45 @@ end
 
 App.map_key :mouse_left, :press
 
+start = Time.now
+c_ = 0.0
+c_c = 0
+
 main_scene.on_update do |delta_time|
-  # puts "Delta time: #{delta_time}ms"
+  c_ += delta_time
+  c_c += 1
+
+  # puts "Delta time: #{delta_time}s"
   # commented out to avoid spamming the console, but you can uncomment to see the delta time being printed every frame
   # runs at 60fps, so you should see around 16-17ms being printed
 
   el = main_scene.elements_at(App.mouse_position)
 
-  puts App.text_input if App.text_input != ""
+  pp App.text_input if App.text_input != ""
 
   next unless App.pressed?(:press)
   
-  puts "#{App.pressed?(:press)}, #{App.down?(:press)}, #{App.released?(:press)}"
+  pp "#{App.pressed?(:press)}, #{App.down?(:press)}, #{App.released?(:press)}"
 
   for elem in el
     if elem == image_element
-      puts "Down over image element"
+      pp "Down over image element"
     elsif elem == rect
-      puts "Down over rect element"
+      pp "Down over rect element"
     elsif elem == text
-      puts "Down over text element"
+      pp "Down over text element"
     end
   end
-
 end
 
 main_scene << text
 main_scene << rect
 main_scene << image_element
 
-# main_scene.delete(text) # Uncomment to test element deletion
+main_scene.delete(text)
 
-App.start main_scene
+App.start main_scene
+
+p "Average delta time: #{c_ / c_c}s"
+p "Time since start (real): #{Time.now - start}s"
+p "Time since start (from dt): #{c_}s"

src/main.cc

@@ -1,6 +1,7 @@
 #include "binding/definitions.h"
 
 int main(int argc, char *argv[]) {
+  Ruby::load_mgems();
   definitions::setup();
 
   char *startup_script = nullptr;

src/window/window.cc

@@ -451,14 +451,17 @@ const char *Window::paste() {
 }
 
 uint64_t Window::get_time() {
-  return SDL_GetTicks();
+  return SDL_GetTicksNS();
 }
 
 uint64_t Window::delta_time() {
   static uint64_t last_time = 0;
-  uint64_t current_time = SDL_GetTicks();
+  static bool first_call = 1;
+  uint64_t current_time = SDL_GetTicksNS();
   uint64_t delta = current_time - last_time;
   last_time = current_time;
+  if (first_call)
+    return (first_call = 0);
   return delta;
 }
 

writeup/analysis.md

@@ -234,6 +234,7 @@ Other features that a game engine should have/has (need to go in depth)
 - audio playing
 - network interface, with a lib to work with rack backends (and generic socket api)
 - persistence store
+- rng helpers
 
 ## Embedded scripting language choice.