Arc Direction followup for circles (#20314)

Marlin/src/gcode/motion/G2_G3.cpp

@@ -80,24 +80,26 @@ void plan_arc(
   // Angle of rotation between position and target from the circle center.
   float angular_travel = ATAN2(rvec.a * rt_Y - rvec.b * rt_X, rvec.a * rt_X + rvec.b * rt_Y);
 
-  // Make sure angular travel over 180 degrees goes the other way around.
-  switch (((angular_travel < 0) << 1) + clockwise) {
-    case 1: angular_travel -= RADIANS(360); break; // Positive but CW? Reverse direction.
-    case 2: angular_travel += RADIANS(360); break; // Negative but CCW? Reverse direction.
-  }
-
   #ifdef MIN_ARC_SEGMENTS
-    uint16_t min_segments = CEIL((MIN_ARC_SEGMENTS) * ABS(angular_travel) / RADIANS(360));
-    NOLESS(min_segments, 1U);
+    uint16_t min_segments = MIN_ARC_SEGMENTS;
   #else
     constexpr uint16_t min_segments = 1;
   #endif
 
-  // Make a circle if the angular rotation is 0 and the target is current position
-  if (NEAR_ZERO(angular_travel) && NEAR(current_position[p_axis], cart[p_axis]) && NEAR(current_position[q_axis], cart[q_axis])) {
-    angular_travel = RADIANS(360);
+  // Do a full circle if angular rotation is near 0 and the target is current position
+  if ((!angular_travel || NEAR_ZERO(angular_travel)) && NEAR(current_position[p_axis], cart[p_axis]) && NEAR(current_position[q_axis], cart[q_axis])) {
+    // Preserve direction for circles
+    angular_travel = clockwise ? -RADIANS(360) : RADIANS(360);
+  }
+  else {
+    // Make sure angular travel over 180 degrees goes the other way around.
+    switch (((angular_travel < 0) << 1) | clockwise) {
+      case 1: angular_travel -= RADIANS(360); break; // Positive but CW? Reverse direction.
+      case 2: angular_travel += RADIANS(360); break; // Negative but CCW? Reverse direction.
+    }
     #ifdef MIN_ARC_SEGMENTS
-      min_segments = MIN_ARC_SEGMENTS;
+      min_segments = CEIL(min_segments * ABS(angular_travel) / RADIANS(360));
+      NOLESS(min_segments, 1U);
     #endif
   }