align rotations

__init__.py

@@ -446,6 +446,8 @@ class FONT3D_OT_TestFont(bpy.types.Operator):
                     ob.constraints["Follow Path"].use_curve_follow = True
                     ob.constraints["Follow Path"].forward_axis = "FORWARD_X"
                     ob.constraints["Follow Path"].up_axis = "UP_Y"
+                    # samplecurve = nodes.new(type="GeometryNodeSampleCurve")
+
                     # butils.ShowMessageBox("WHAT","INFO","I don't really know what you mean, lsaidry")
                 else:
                     offset.x = advance

butils.py

@@ -8,6 +8,11 @@ if "Font" in locals():
 else:
     from .common import Font
 
+if "utils" in locals():
+    importlib.reload(utils)
+else:
+    from .common import utils
+
 def apply_all_transforms(obj):
     mb = obj.matrix_basis
     if hasattr(obj.data, "transform"):
@@ -25,13 +30,10 @@ def get_parent_collection_names(collection, parent_names):
 
 # Ensure it's a curve object
 # TODO: no raising, please
-def get_curve_length(obj, num_samples = 100):
+def get_curve_length(curve_obj, num_samples = 100):
     total_length = 0
 
-    if obj.type != 'CURVE':
+    curve = curve_obj.data
-        raise TypeError("The selected object is not a curve")
-
-    curve = obj.data
 
     # Loop through all splines in the curve
     for spline in curve.splines:
@@ -39,6 +41,175 @@ def get_curve_length(obj, num_samples = 100):
     
     return total_length
 
+def calc_point_on_bezier(bezier_point_1, bezier_point_2, t):
+    p1 = bezier_point_1.co
+    h1 = bezier_point_1.handle_right
+    p2 = bezier_point_2.co
+    h2 = bezier_point_2.handle_left
+    return ((1 - t)**3) * p1 + (3 * t * (1 - t)**2) * h1 + (3 * (t**2) * (1 - t)) * h2 + (t**3) * p2
+
+def calc_tangent_on_bezier(bezier_point_1, bezier_point_2, t):
+    p1 = bezier_point_1.co
+    h1 = bezier_point_1.handle_right
+    p2 = bezier_point_2.co
+    h2 = bezier_point_2.handle_left
+    return (
+            (-3 * (1 - t)**2) * p1 + (-6 * t * (1 - t) + 3 * (1 - t)**2) * h1 +
+            (-3 * (t**2) + 6 * t * (1 - t)) * h2 + (3 * t**2) * p2
+            ).normalized()
+
+from math import radians, sqrt, pi, acos
+
+def align_rotations_auto_pivot(mask, input_rotations, vectors, factors, local_main_axis):
+    output_rotations = [mathutils.Matrix().to_3x3() for _ in range(len(input_rotations))]
+
+    for i in mask:
+        vector = mathutils.Vector(vectors[i]).normalized()
+        input_rotation = mathutils.Euler(input_rotations[i])
+
+        if vector.length < 1e-6:
+            output_rotations[i] = input_rotation.to_matrix()
+            continue
+
+        old_rotation = input_rotation.to_matrix()
+        old_axis = (old_rotation @ local_main_axis).normalized()
+        new_axis = vector
+        # rotation_axis = (-(old_axis) + new_axis).normalized()
+        rotation_axis = old_axis.cross(new_axis).normalized()
+
+        if rotation_axis.length < 1e-6:
+            # Vectors are linearly dependent, fallback to another axis
+            rotation_axis = (old_axis + mathutils.Matrix().col[2]).normalized()
+            
+            if rotation_axis.length < 1e-6:
+                # This is now guaranteed to not be zero
+                rotation_axis = (-(old_axis) + mathutils.Matrix().col[1]).normalized()
+
+        # full_angle = radians(sqrt((4 * pow(input_rotation.to_quaternion().dot(mathutils.Quaternion(vectors[i].normalized())), 2) - 3)))
+        # dot = old_axis.dot(new_axis)
+        # normalized_diff = (old_axis - new_axis).normalized()
+        # full_angle = acos(min((old_axis * new_axis + normalized_diff.dot(2)).length, 1))
+        full_angle = old_axis.angle(new_axis)
+        angle = factors[i] * full_angle
+
+        rotation = mathutils.Quaternion(rotation_axis, angle).to_matrix()
+        new_rotation_matrix = old_rotation @ rotation
+        output_rotations[i] = new_rotation_matrix
+
+    return [mat.to_4x4() for mat in output_rotations]
+
+def calc_bezier_length(bezier_point_1, bezier_point_2, resolution=20):
+    step = 1/resolution
+    previous_p = bezier_point_1.co
+    length = 0
+    for i in range(0, resolution):
+        t = (i + 1) * step
+        p = calc_point_on_bezier(bezier_point_1, bezier_point_2, t)
+        length += (p - previous_p).length
+        previous_p = p
+    return length
+
+def calc_point_on_bezier_spline(bezier_spline_obj,
+                                distance,
+                                output_tangent = False,
+                                resolution_factor = 1.0):
+    # what's the point of just one point
+    # assert len(bezier_spline_obj.bezier_points) >= 2
+    # however, maybe let's have it not crash and do this
+    if len(bezier_spline_obj.bezier_points) < 1:
+        print("butils::calc_point_on_bezier_spline: whoops, no points. panicking. return 0,0,0")
+        if output_tangent:
+            return mathutils.Vector((0,0,0)), mathutils.Vector((1,0,0))
+        else:
+            return mathutils.Vector((0,0,0))
+    if len(bezier_spline_obj.bezier_points) == 1:
+        p = bezier_spline_obj.bezier_points[0]
+        travel = (p.handle_left - p.co).normalized() * distance
+        if output_tangent:
+            tangent = mathutils.Vector((1,0,0))
+            return travel, tangent
+        else:
+            return travel
+    
+    if distance <= 0:
+        p = bezier_spline_obj.bezier_points[0]
+        travel = (p.co - p.handle_left).normalized() * distance
+        location = p.co + travel
+        if output_tangent:
+            p2 = bezier_spline_obj.bezier_points[1]
+            tangent = calc_tangent_on_bezier(p, p2, 0)
+            return location, tangent
+        else:
+            return location
+
+    beziers = []
+    lengths = []
+    total_length = 0
+    n_bezier_points = len(bezier_spline_obj.bezier_points)
+    for i in range(0, len(bezier_spline_obj.bezier_points) - 1):
+       bezier = [ bezier_spline_obj.bezier_points[i],
+                  bezier_spline_obj.bezier_points[i + 1] ]
+       length = calc_bezier_length(bezier[0],
+                                   bezier[1],
+                                   int(bezier_spline_obj.resolution_u * resolution_factor))
+       total_length += length
+       beziers.append(bezier)
+       lengths.append(length)
+       # if total_length > distance:
+           # break
+
+    iterated_distance = 0
+    for i in range(0, len(beziers)):
+        if iterated_distance + lengths[i] > distance:
+            distance_on_bezier = (distance - iterated_distance)
+            d = distance_on_bezier / lengths[i]
+            print(f"i: {i}, d: {d}, distance_on_bezier: {distance_on_bezier}, distance: {distance}")
+            location = calc_point_on_bezier(beziers[i][0],
+                                            beziers[i][1],
+                                            d)
+            if output_tangent:
+                tangent = calc_tangent_on_bezier(beziers[i][0],
+                                                 beziers[i][1],
+                                                 d)
+                return location, tangent
+            else:
+                return location
+        iterated_distance += lengths[i]
+    # if we are here, the point is outside the spline
+    last_i = len(beziers) - 1
+    p = beziers[last_i][1]
+    travel = (p.handle_right - p.co).normalized() * (distance - total_length)
+    location = p.co + travel
+    if output_tangent:
+        tangent = calc_tangent_on_bezier(beziers[last_i][0],
+                                         p,
+                                         1)
+        return location, tangent
+    else:
+        return location
+
+
+def calc_point_on_bezier_curve(bezier_curve_obj,
+                               distance,
+                               output_tangent = False,
+                               resolution_factor = 1.0):
+    curve = bezier_curve_obj.data
+
+    # Loop through all splines in the curve
+    total_length = 0
+    for i, spline in enumerate(curve.splines):
+        resolution = int(spline.resolution_u * resolution_factor)
+        length = spline.calc_length(resolution=resolution)
+        if total_length + length > distance or i == len(curve.splines) - 1:
+            return calc_point_on_bezier_spline(spline,
+                                               (distance - total_length),
+                                               output_tangent,
+                                               resolution_factor)
+        total_length += length
+
+    # TODO: can this fail?
+
+
 # def get_objects_by_name(name, startswith="", endswith=""):
     # return [obj for obj in bpy.context.scene.objects if obj.name.startswith(startswith) and if obj.name.endswith(endswith)]
 

common/utils.py

@@ -1,6 +1,9 @@
 
 import time
 import datetime
+from mathutils import (
+        Vector,
+        )
 
 def get_timestamp():
     return datetime.datetime \
@@ -16,3 +19,26 @@ def mapRange(in_value, in_min, in_max, out_min, out_max, clamp=False):
             return max(out_max, min(out_min, output))
     else:
         return output
+
+# # Evaluate a bezier curve for the parameter 0<=t<=1 along its length
+# def evaluateBezierPoint(p1, h1, h2, p2, t):
+    # return ((1 - t)**3) * p1 + (3 * t * (1 - t)**2) * h1 + (3 * (t**2) * (1 - t)) * h2 + (t**3) * p2
+
+
+# # Evaluate the unit tangent on a bezier curve for t
+# def evaluateBezierTangent(p1, h1, h2, p2, t):
+    # return (
+            # (-3 * (1 - t)**2) * p1 + (-6 * t * (1 - t) + 3 * (1 - t)**2) * h1 +
+            # (-3 * (t**2) + 6 * t * (1 - t)) * h2 + (3 * t**2) * p2
+            # ).normalized()
+
+# def calculateBezierLength(p1, h1, h2, p2, resolution=20):
+   # step = 1/resolution
+   # previous_p = p1
+   # length = 0
+   # for i in range(0, resolution):
+       # t = (i + 1) * step
+       # p = evaluateBezierPoint(p1, h1, h2, p2, t)
+       # length += p.distance(previous_p)
+       # previous_p = p
+    # return length