From a5b8e411e3f830048267ef783d348336a27424d5 Mon Sep 17 00:00:00 2001
From: "Zed A. Shaw" <zed.shaw@gmail.com>
Date: Sun, 13 Apr 2025 15:17:08 -0400
Subject: [PATCH] I can now apply shaders to any GUI element, but I need a
 shader manager that will allow for hot reloading and tracking input/output
 variables.

---
 Makefile                     |  2 +-
 combat_ui.cpp                |  5 +--
 constants.hpp                |  4 +--
 guecs.cpp                    | 60 ++++++++++++++++++++++++++++++------
 guecs.hpp                    | 30 ++++++++++++++++++
 raycaster.cpp                |  2 +-
 shaders/ui_shader.frag       | 22 +++++++++++++
 shaders/ui_shape_shader.frag | 12 ++++++++
 8 files changed, 121 insertions(+), 16 deletions(-)
 create mode 100644 shaders/ui_shader.frag
 create mode 100644 shaders/ui_shape_shader.frag

diff --git a/Makefile b/Makefile
index cc2ac86..562ac6d 100644
--- a/Makefile
+++ b/Makefile
@@ -22,7 +22,7 @@ tracy_build:
 	meson compile -j 10 -C builddir
 
 test: build
-	./builddir/runtests "[combat-battle]"
+	./builddir/runtests
 
 run: build test
 	powershell "cp ./builddir/zedcaster.exe ."
diff --git a/combat_ui.cpp b/combat_ui.cpp
index aa5b455..0be735e 100644
--- a/combat_ui.cpp
+++ b/combat_ui.cpp
@@ -15,9 +15,10 @@ namespace gui {
 
   void CombatUI::make_button(std::string name, std::wstring label, Events::GUI event) {
     auto button = $gui.entity(name);
-    // $gui.set<Sprite>(button, {"leather_pouch-128"});
-    $gui.set<Rectangle>(button, {});
+    $gui.set<Sprite>(button, {"leather_pouch-128"});
+    // $gui.set<Rectangle>(button, {});
     $gui.set<Label>(button, {label});
+    $gui.set<Shader>(button, {.duration=0.2f});
     $gui.set<Clickable>(button,
         guecs::make_action(*$level.world, event));
   }
diff --git a/constants.hpp b/constants.hpp
index e6ccf60..1a7d6ad 100644
--- a/constants.hpp
+++ b/constants.hpp
@@ -72,8 +72,8 @@ constexpr int COMBAT_UI_HEIGHT = SCREEN_HEIGHT - RAY_VIEW_HEIGHT;
 constexpr wchar_t BG_TILE = L'█';
 constexpr wchar_t UI_BASE_CHAR = L'█';
 constexpr int BG_BOX_OFFSET=5;
-constexpr const char *FONT_FILE_NAME="./assets/text.otf";
-
+constexpr const char *FONT_FILE_NAME="assets/text.otf";
+constexpr const char *DEFAULT_UI_SHADER = "shaders/ui_shader.frag";
 
 constexpr std::array<std::wstring, 8> COMPASS{
     // L"E", L"SE", L"S", L"SW", L"W", L"NW", L"N", L"NE"
diff --git a/guecs.cpp b/guecs.cpp
index 5fb2029..24eff7c 100644
--- a/guecs.cpp
+++ b/guecs.cpp
@@ -65,6 +65,33 @@ namespace guecs {
     shape->setFillColor(color);
   }
 
+  void Shader::init(lel::Cell &cell) {
+    ptr = std::make_shared<sf::Shader>();
+    bool good = ptr->loadFromFile(name, sf::Shader::Type::Fragment);
+    dbc::check(good, fmt::format("failed to load shader {}", name));
+    ptr->setUniform("u_resolution", sf::Vector2f({float(cell.w), float(cell.h)}));
+
+    clock = std::make_shared<sf::Clock>();
+  }
+
+  void Shader::step() {
+    sf::Time u_time = clock->getElapsedTime();
+    float current_time = u_time.asSeconds();
+
+    if(current_time < u_time_end) {
+      ptr->setUniform("u_time", current_time);
+    } else {
+      active = false;
+    }
+  }
+
+  void Shader::run() {
+    active = true;
+    sf::Time u_time = clock->getElapsedTime();
+    u_time_end = u_time.asSeconds() + duration;
+    ptr->setUniform("u_duration", duration);
+    ptr->setUniform("u_time_end", u_time_end);
+  }
 
   UI::UI() {
     $font = make_shared<sf::Font>(FONT_FILE_NAME);
@@ -114,6 +141,10 @@ namespace guecs {
       rect.init(cell);
     });
 
+    $world.query<lel::Cell, Shader>([](auto, auto& cell, auto& shader) {
+        shader.init(cell);
+    });
+
     $world.query<Rectangle, Meter>([](auto, auto& bg, auto &) {
         bg.shape->setFillColor(ColorValue::BLACK);
     });
@@ -152,27 +183,31 @@ namespace guecs {
       window.draw(*bg.shape);
     }
 
-    $world.query<Rectangle>([&](auto, auto& rect) {
-        window.draw(*rect.shape);
+    $world.query<Shader>([&](auto, auto& shader) {
+      if(shader.active) shader.step();
     });
 
-    $world.query<lel::Cell, Meter>([&](auto, auto& cell, const auto &meter) {
+    $world.query<Rectangle>([&](auto ent, auto& rect) {
+        render_helper(window, ent, true, rect.shape);
+    });
+
+    $world.query<lel::Cell, Meter>([&](auto ent, auto& cell, const auto &meter) {
         float level = std::clamp(meter.percent, 0.0f, 1.0f) * float(cell.w);
         // ZED: this 6 is a border width, make it a thing
         meter.bar.shape->setSize({std::max(level, 0.0f), float(cell.h - 6)});
-        window.draw(*meter.bar.shape);
+        render_helper(window, ent, true, meter.bar.shape);
     });
 
-    $world.query<Sprite>([&](auto, auto& sprite) {
-        window.draw(*sprite.sprite);
+    $world.query<Sprite>([&](auto ent, auto& sprite) {
+        render_helper(window, ent, false, sprite.sprite);
     });
 
-    $world.query<Label>([&](auto, auto& text) {
-        window.draw(*text.text);
+    $world.query<Label>([&](auto ent, auto& text) {
+        render_helper(window, ent, false, text.text);
     });
 
-    $world.query<Textual>([&](auto, auto& text) {
-        window.draw(*text.text);
+    $world.query<Textual>([&](auto ent, auto& text) {
+        render_helper(window, ent, true, text.text);
     });
   }
 
@@ -183,6 +218,11 @@ namespace guecs {
       if((x >= cell.x && x <= cell.x + cell.w) &&
           (y >= cell.y && y <= cell.y + cell.h))
       {
+        if($world.has<Shader>(ent)) {
+          auto& shader = $world.get<Shader>(ent);
+          shader.run();
+        }
+
         if(auto action_data = get_if<ActionData>(ent)) {
           clicked.action(ent, action_data->data);
         } else {
diff --git a/guecs.hpp b/guecs.hpp
index 79262c5..ebce9d1 100644
--- a/guecs.hpp
+++ b/guecs.hpp
@@ -81,6 +81,19 @@ namespace guecs {
     std::string name;
   };
 
+  struct Shader {
+    float duration = 0.1f;
+    std::string name{DEFAULT_UI_SHADER};
+    float u_time_end = 0.0;
+    bool active = false;
+    std::shared_ptr<sf::Shader> ptr = nullptr;
+    std::shared_ptr<sf::Clock> clock = nullptr;
+
+    void init(lel::Cell &cell);
+    void run();
+    void step();
+  };
+
   struct Background {
     float x = 0.0f;
     float y = 0.0f;
@@ -178,6 +191,22 @@ namespace guecs {
         remove<Comp>(ent);
       }
 
+      template<typename T>
+      void render_helper(sf::RenderWindow& window, DinkyECS::Entity ent, bool is_shape, T& target) {
+        sf::Shader *shader_ptr = nullptr;
+
+        if($world.has<Shader>(ent)) {
+          auto& shader = $world.get<Shader>(ent);
+
+          if(shader.active) {
+            shader_ptr = shader.ptr.get();
+            shader_ptr->setUniform("is_shape", is_shape);
+          }
+        }
+
+        window.draw(*target, shader_ptr);
+      }
+
       void show_sprite(string region, string sprite_name);
       void show_text(string region, wstring content);
       void update_text(string region, wstring content);
@@ -186,4 +215,5 @@ namespace guecs {
   };
 
   Clickable make_action(DinkyECS::World& target, Events::GUI event);
+
 }
diff --git a/raycaster.cpp b/raycaster.cpp
index e96977f..ab7e838 100644
--- a/raycaster.cpp
+++ b/raycaster.cpp
@@ -393,7 +393,7 @@ void Raycaster::update_level(GameLevel level) {
 }
 
 void Raycaster::init_shaders() {
-  dbc::check(sf::Shader::isAvailable(), "no shaders?!");
+  // dbc::check(sf::Shader::isAvailable(), "no shaders?!");
   bool good = $brightness.loadFromFile("shaders/modal.frag", sf::Shader::Type::Fragment);
   dbc::check(good, "shader could not be loaded");
   $brightness.setUniform("source", sf::Shader::CurrentTexture);
diff --git a/shaders/ui_shader.frag b/shaders/ui_shader.frag
new file mode 100644
index 0000000..d599f7c
--- /dev/null
+++ b/shaders/ui_shader.frag
@@ -0,0 +1,22 @@
+uniform vec2 u_resolution;
+uniform vec2 u_mouse;
+uniform float u_duration;
+uniform float u_time;
+uniform float u_time_end;
+uniform sampler2D texture;
+uniform bool is_shape;
+
+void main() {
+  if(is_shape) {
+    float tick = (u_time_end - u_time) / u_duration;
+    float blink = smoothstep(1.0, 0.5, tick);
+    vec4 color = vec4(blink, blink, blink, 1.0);
+    gl_FragColor = gl_Color * color;
+  } else {
+    vec4 pixel = texture2D(texture, gl_TexCoord[0].xy);
+    float tick = (u_time_end - u_time) / u_duration;
+    float blink = smoothstep(1.0, 0.5, tick);
+    vec4 color = vec4(blink, blink, blink, 1.0);
+    gl_FragColor = gl_Color * color * pixel;
+  }
+}
diff --git a/shaders/ui_shape_shader.frag b/shaders/ui_shape_shader.frag
new file mode 100644
index 0000000..c16d6ea
--- /dev/null
+++ b/shaders/ui_shape_shader.frag
@@ -0,0 +1,12 @@
+uniform vec2 u_resolution;
+uniform vec2 u_mouse;
+uniform float u_duration;
+uniform float u_time;
+uniform float u_time_end;
+
+void main() {
+  float tick = (u_time_end - u_time) / u_duration;
+  float blink = smoothstep(1.0, 0.5, tick);
+  vec4 color = vec4(blink, blink, blink, 1.0);
+  gl_FragColor = gl_Color * color;
+}