From a6517b89829a0e90025fd451fb4a453e8a936376 Mon Sep 17 00:00:00 2001
From: Stephen Seo <seo.disparate@gmail.com>
Date: Wed, 22 Jul 2020 19:03:33 +0900
Subject: [PATCH] Render to cache that only updates on click

This is to prevent slowdown when drawing per frame. Previously, the
program would draw each individual triangle each frame. Now the draws
are cached to a texture that is drawn each frame, and the cache is
recreated on click or undo/redo events.
---
 src/state.cpp | 32 ++++++++++++++++++++++++++++++--
 src/state.hpp |  8 ++++++++
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/src/state.cpp b/src/state.cpp
index 6f659e5..a249f67 100644
--- a/src/state.cpp
+++ b/src/state.cpp
@@ -38,6 +38,16 @@ bgColor(sf::Color::Black)
     pointCircle.setOutlineThickness(1.0f);
 
     saveFilenameBuffer.fill(0);
+
+    if(!drawCache.create(800, 600)) {
+#ifndef NDEBUG
+        puts("ERROR: Failed to initialize RenderTexture (draw cache)");
+#endif
+        flags.reset(8);
+    } else {
+        flags.set(8);
+        drawCacheSprite.setTexture(drawCache.getTexture(), true);
+    }
 }
 
 Tri::State::~State() {
@@ -56,6 +66,7 @@ void Tri::State::handle_events() {
                 if(event.key.code == sf::Keyboard::H) {
                     flags.flip(0);
                 } else if(event.key.code == sf::Keyboard::U) {
+                    flags.set(7);
                     if(currentTri_state > 0) {
                         switch(currentTri_state) {
                         case FIRST:
@@ -72,6 +83,7 @@ void Tri::State::handle_events() {
                         --trisIndex;
                     }
                 } else if(event.key.code == sf::Keyboard::R) {
+                    flags.set(7);
                     if(currentTri_state != CurrentState::NONE
                             && currentTri_state < currentTri_maxState) {
                         switch(currentTri_state) {
@@ -109,7 +121,8 @@ void Tri::State::handle_events() {
                 }
             }
         } else if(event.type == sf::Event::MouseButtonPressed) {
-            if(!flags.test(2) && !flags.test(5) && !flags.test(6)) {
+            if(!is_in_clickable_menu()) {
+                flags.set(7);
                 switch(currentTri_state) {
                 case CurrentState::NONE:
                     currentTri[0] = sf::Vector2f(event.mouseButton.x, event.mouseButton.y);
@@ -184,7 +197,18 @@ void Tri::State::update() {
 }
 
 void Tri::State::draw() {
-    draw_to_target(&window);
+    if(flags.test(8)) {
+        // draw cache initialized
+        if(flags.test(7)) {
+            // draw cache dirty
+            flags.reset(7);
+            draw_to_target(&drawCache);
+            drawCache.display();
+        }
+        window.draw(drawCacheSprite);
+    } else {
+        draw_to_target(&window);
+    }
 
     // draw gui stuff
     ImGui::SFML::Render(window);
@@ -276,3 +300,7 @@ std::string_view Tri::State::failed_save_message() const {
 void Tri::State::close_save() {
     flags.reset(6);
 }
+
+bool Tri::State::is_in_clickable_menu() const {
+    return flags.test(2) || flags.test(5) || flags.test(6);
+}
diff --git a/src/state.hpp b/src/state.hpp
index e8bf36e..96a364e 100644
--- a/src/state.hpp
+++ b/src/state.hpp
@@ -24,6 +24,8 @@ namespace Tri {
          * 4 - bg color picker color dirty
          * 5 - display bg color picker
          * 6 - draw save
+         * 7 - draw cache dirty
+         * 8 - draw cache initialized
          */
         typedef std::bitset<64> BitsetType;
         BitsetType flags;
@@ -50,6 +52,9 @@ namespace Tri {
         FilenameBufferType saveFilenameBuffer;
         std::string failedSaveMessage;
 
+        sf::RenderTexture drawCache;
+        sf::Sprite drawCacheSprite;
+
     public:
         void handle_events();
         void update();
@@ -73,6 +78,9 @@ namespace Tri {
         bool do_save();
         std::string_view failed_save_message() const;
         void close_save();
+
+    private:
+        bool is_in_clickable_menu() const;
     };
 }