Render fps independent video fps

1 files changed, 9 insertions, 5 deletions

diff --git a/src/main.cpp b/src/main.cpp
index 78e3221..0359622 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -4,6 +4,8 @@
 #include <deque>
 
 int main() {
+    const int fps = 24;
+
     sf::Texture texture;
     if(!texture.loadFromFile("flag.png"))
         return 1;
@@ -12,8 +14,8 @@ int main() {
 
     sf::Vector2u window_size = texture.getSize();
     sf::RenderWindow window(sf::VideoMode(window_size.x, window_size.y), "SFML works!", 0);
-    window.setVerticalSyncEnabled(true);
-    window.setFramerateLimit(24);
+    window.setVerticalSyncEnabled(false);
+    window.setFramerateLimit(0);
 
     sf::Shader shader;
     if(!shader.loadFromFile("flag.glsl", sf::Shader::Type::Fragment))
@@ -64,8 +66,9 @@ int main() {
     output_image.create(flag_width, flag_height, sf::Color::Transparent);
 
     const float playtime_sec = 2.0f;
+    const float frame_time = 1000.0 / (double)fps / 1000.0;
+    double elapsed_frame_time = 0.0;
 
-    sf::Clock timer;
     while (window.isOpen()) {
         sf::Event event;
         while (window.pollEvent(event)) {
@@ -73,7 +76,7 @@ int main() {
                 window.close();
         }
 
-        shader.setUniform("iTime", timer.getElapsedTime().asSeconds());
+        shader.setUniform("iTime", (float)elapsed_frame_time);
         window.clear(sf::Color::Transparent);
         window.draw(vertex, 4, sf::PrimitiveType::Quads, &shader);
         window.display();
@@ -85,7 +88,8 @@ int main() {
         std::lock_guard<std::mutex> lock(images_lock);
         pending_frames.push_back(output_image);
 
-        if(timer.getElapsedTime().asSeconds() >= playtime_sec)
+        elapsed_frame_time += frame_time;
+        if(elapsed_frame_time >= playtime_sec)
             break;
     }