Use new ode API

src/VCF.cpp

@@ -32,17 +32,17 @@ struct LadderFilter {
 	}
 
 	void process(float input, float dt) {
-		stepRK4(0.f, dt, state, 4, [&](float t, const float y[], float dydt[]) {
-			float inputc = clip(input - resonance * y[3]);
-			float yc0 = clip(y[0]);
-			float yc1 = clip(y[1]);
-			float yc2 = clip(y[2]);
-			float yc3 = clip(y[3]);
-
-			dydt[0] = omega0 * (inputc - yc0);
-			dydt[1] = omega0 * (yc0 - yc1);
-			dydt[2] = omega0 * (yc1 - yc2);
-			dydt[3] = omega0 * (yc2 - yc3);
+		ode::stepRK4(0.f, dt, state, 4, [&](float t, const float x[], float dxdt[]) {
+			float inputc = clip(input - resonance * x[3]);
+			float yc0 = clip(x[0]);
+			float yc1 = clip(x[1]);
+			float yc2 = clip(x[2]);
+			float yc3 = clip(x[3]);
+
+			dxdt[0] = omega0 * (inputc - yc0);
+			dxdt[1] = omega0 * (yc0 - yc1);
+			dxdt[2] = omega0 * (yc1 - yc2);
+			dxdt[3] = omega0 * (yc2 - yc3);
 		});
 
 		lowpass = state[3];