rename animation => transition

src/util/transition.cpp

@@ -0,0 +1,27 @@
+#include <llmr/util/transition.hpp>
+#include <llmr/util/unitbezier.hpp>
+#include <llmr/platform/platform.hpp>
+
+using namespace llmr::util;
+
+UnitBezier ease(0.25, 0.1, 0.25, 1);
+
+transition::~transition() {}
+
+ease_transition::ease_transition(double from, double to, double &value, time start, time duration)
+    : transition(start, duration),
+      from(from),
+      to(to),
+      value(value) {
+}
+
+transition::state ease_transition::update(time now) const {
+    float t = progress(now);
+    if (t >= 1) {
+        value = to;
+        return complete;
+    } else {
+        value = from + (to - from) * ease.solve(t, 0.001);
+        return running;
+    }
+}