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Fix G2/G3 arcs > 180° (MarlinFirmware#20292)
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yysh12 authored and thinkyhead committed Apr 26, 2021
1 parent 8bfc8c0 commit 46257ac
Showing 1 changed file with 16 additions and 9 deletions.
25 changes: 16 additions & 9 deletions Marlin/src/gcode/motion/G2_G3.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -77,22 +77,29 @@ void plan_arc(
rt_Y = cart[q_axis] - center_Q,
start_L = current_position[l_axis];

// CCW angle of rotation between position and target from the circle center. Only one atan2() trig computation required.
// 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);
if (angular_travel < 0) angular_travel += RADIANS(360);

#ifdef MIN_ARC_SEGMENTS
uint16_t min_segments = CEIL((MIN_ARC_SEGMENTS) * (angular_travel / RADIANS(360)));
NOLESS(min_segments, 1U);
uint16_t min_segments = MIN_ARC_SEGMENTS;
#else
constexpr uint16_t min_segments = 1;
#endif
if (clockwise) angular_travel -= RADIANS(360);

// 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
}

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