Adjust translation with mouse to be pixel-perfect, and zoom occurs around the screen-center now.

include/FractalApp.hpp

@@ -35,6 +35,22 @@ enum class Fractal {
     MandelbrotSet, JuliaSet
 };
 
+
+template <typename T>
+struct Lerped {
+
+    T current;
+    T goal;
+    float rate = 1.f;
+    void Update(float elapsed);
+};
+
+template <>
+inline void Lerped<float>::Update(float elapsed) { current = Math::Lerp(current, goal, elapsed*rate); }
+
+template <>
+inline void Lerped<Vector2>::Update(float elapsed) { current = Vector2::Lerp(current, goal, elapsed*rate); }
+
 /// This class represents the FractalApp program state.
 class FractalInspectorApp : public ReWindow::OpenGLWindow {
 protected:

main.cpp

@@ -3,9 +3,6 @@
 /// (c) 2025 redacted.cc
 /// This work is explicitly dedicated to the Public Domain.
 
-
-
-
 #include <FractalApp.hpp>
 
 int main(int argc, char** argv) {

src/FractalApp.cpp

@@ -413,7 +413,7 @@ void FractalInspectorApp::Update(float elapsed) {
     }
 
     // TODO: Vary the rate appropriately.
-    float rate = elapsed * 0.125f;
+    float rate = elapsed * 0.25f;
 
     if (IsKeyDown(Keys::LeftShift))
         rate *= 0.125f;
@@ -421,10 +421,18 @@ void FractalInspectorApp::Update(float elapsed) {
     if (IsKeyDown(Keys::LeftControl))
         rate *= 0.125f;
 
-    if (IsKeyDown(Keys::Minus))
+    if (IsKeyDown(Keys::Minus)) {
         u_scale += rate;
-    if (IsKeyDown(Keys::Equals))
+        // Stupid hack to make zoom originate at the center of the screen.
+        u_translation += Vector2(0.5f, 0.5f)*rate;
+    }
+
+    if (IsKeyDown(Keys::Equals)) {
         u_scale -= rate;
+        // Stupid hack to make zoom originate at the center of the screen.
+        u_translation -= Vector2(0.5f, 0.5f)*rate;
+    }
+
 
     if (IsKeyDown(Keys::DownArrow))
         u_translation.y += rate;
@@ -447,10 +455,10 @@ void FractalInspectorApp::Update(float elapsed) {
 
 
     // TODO: Consider moving this logic deeper into the shader to make it easier to work with.
-    float readable_scale = Math::Round(ReadableScale(), 3);
+    float readable_scale = Math::Round(ReadableScale(), 4);
 
     std::string fps_text = std::format("Pos: {},{} Zoom: {}x FPS: {}",
-        Math::Round(u_translation.x, 2), Math::Round(u_translation.y, 2), readable_scale, fps);
+        Math::Round(u_translation.x, 4), Math::Round(u_translation.y, 4), readable_scale, fps);
 
     fps_label->SetContent(fps_text);
 }
@@ -580,11 +588,16 @@ void FractalInspectorApp::OnMouseMove(const ReWindow::MouseMoveEvent &e) {
     // TODO: e.Delta is always 0, investigate in JUI.
     Vector2 delta = nmp - last;
 
-    float bias_slowdown_as_we_zoom_in = 1.125f;
-    float base_slowdown = 0.005;
+    float base_slowdown = 768.f;
+    base_slowdown = GetHeight(); // TODO: Compute the actual aspect ratio.
+
+    // Invert vertical.
+    Vector2 pan_direction(delta.x, -delta.y);
+    float pan_rate = u_scale / base_slowdown;
+
 
     if (panning)
-        u_translation += delta*(1.f / ReadableScale()*bias_slowdown_as_we_zoom_in)*base_slowdown;
+        u_translation += pan_direction*pan_rate;
 
     last = nmp;
 }