drawing grid clipping

src/ifcblenderexport/blenderbim/bim/helper.py

@@ -1,4 +1,6 @@
 import math
+from mathutils import geometry
+from mathutils import Vector
 import bpy
 
 
@@ -285,3 +287,94 @@ def format_distance(value, isArea=False, hide_units=True):
         tx_dist = fmt % value
 
     return tx_dist
+
+
+def parse_diagram_scale(camera):
+    """Returns numeric value of scale"""
+    if camera.BIMCameraProperties.diagram_scale == "CUSTOM":
+        _, fraction = camera.BIMCameraProperties.custom_diagram_scale.split("|")
+    else:
+        _, fraction = camera.BIMCameraProperties.diagram_scale.split("|")
+    numerator, denominator = fraction.split("/")
+    return float(numerator) / float(denominator)
+
+
+def ortho_view_frame(camera, margin=0.015):
+    """Calculates 2d bounding box of camera view area.
+
+    Similar to `bpy.types.Camera.view_frame`
+
+    :arg camera: camera of drawing
+    :type camera: bpy.types.Camera + BIMCameraProperties
+    :arg margin: margins, in scene units
+    :type margin: float
+    :return: (xmin, xmax, ymin, ymax) in local camera coordinates
+    """
+    aspect = camera.BIMCameraProperties.raster_y / camera.BIMCameraProperties.raster_x
+    size = camera.ortho_scale
+    hwidth = size * .5
+    hheight = size * .5 * aspect
+    scale = parse_diagram_scale(camera)
+    xmarg = margin * scale
+    ymarg = margin * scale * aspect
+    return (-hwidth + xmarg, hwidth - xmarg, -hheight + ymarg, hheight - ymarg)
+
+
+def clip_segment(bounds, segm):
+    """Clipping line segment to bounds
+
+    :arg bounds: (xmin, xmax, ymin, ymax)
+    :arg segm: 2 vertices of the segment
+    :return: 2 new vertices of segment or None if segment outside the bounding box
+    """
+    # Liang–Barsky algorithm
+
+    def iszero(v):
+        return abs(v) < 1e-10
+
+    xmin, xmax, ymin, ymax = bounds
+    p1, p2 = segm
+
+    dlt = p2 - p1
+    q_l = p1.x - xmin
+    q_r = xmax - p1.x
+    q_t = p1.y - ymin
+    q_b = ymax - p1.y
+
+    pos = [1]
+    neg = [0]
+
+    if (iszero(dlt.x) and (q_l < 0 or q_r < 0)) or (iszero(dlt.y) and (q_t < 0 or q_b < 0)):
+        # parallel to a boundary and outside it
+        return None
+
+    if not iszero(dlt.x):
+        t_l = q_l / -dlt.x
+        t_r = q_r / dlt.x
+        if t_l < 0:
+            neg.append(t_l)
+            pos.append(t_r)
+        else:
+            neg.append(t_r)
+            pos.append(t_l)
+
+    if not iszero(dlt.y):
+        t_t = q_t / -dlt.y
+        t_b = q_b / dlt.y
+        if t_t < 0:
+            neg.append(t_t)
+            pos.append(t_b)
+        else:
+            neg.append(t_b)
+            pos.append(t_t)
+
+    t1 = max(neg)
+    t2 = min(pos)
+
+    if t1 > t2:
+        return None
+
+    p1c = p1 + dlt * t1
+    p2c = p1 + dlt * t2
+
+    return p1c, p2c

src/ifcblenderexport/blenderbim/bim/operator.py

@@ -28,6 +28,7 @@ from . import helper
 from bpy_extras.io_utils import ImportHelper
 from itertools import cycle
 from mathutils import Vector, Matrix, Euler, geometry
+import bmesh
 from math import radians, degrees, atan, tan, cos, sin
 from pathlib import Path
 from bpy.app.handlers import persistent
@@ -4226,13 +4227,42 @@ class CopyGrid(bpy.types.Operator):
             collection.objects.unlink(obj)
 
         source = [obj
-                    for coll in bpy.data.collections
-                    if coll.name.startswith('IfcGrid')
-                    for obj in coll.all_objects
-                    if obj.type == 'MESH']
-        for obj in source:
-            dstobj = obj.copy()
-            dstobj.data = dstobj.data.copy()
-            collection.objects.link(dstobj)
+                  for coll in bpy.data.collections
+                  if coll.name.startswith("IfcGrid")
+                  for obj in coll.all_objects
+                  if obj.name.startswith("IfcGridAxis")]
+        camera = [obj
+                  for obj in collection.all_objects
+                  if obj.type == 'CAMERA'][0]
+
+        clipping = camera.data.type == 'ORTHO'
+        bounds = helper.ortho_view_frame(camera.data) if clipping else None
+
+        for src in source:
+            bm = bmesh.new()
+            bm.from_mesh(src.data)
+            bm.verts.ensure_lookup_table()
+
+            if clipping:
+                proj = src.matrix_world @ camera.matrix_world.inverted()
+                unproj = src.matrix_world.inverted() @ camera.matrix_world
+
+                bm.transform(proj)
+
+                points_orig = [v.co for v in bm.verts[0:2]]
+                points_clip = helper.clip_segment(bounds, points_orig)
+
+                if points_clip is None:
+                    continue
+
+                bm.verts[0].co = points_clip[0]
+                bm.verts[1].co = points_clip[1]
+
+                bm.transform(unproj)
+
+            dst = src.copy()
+            dst.data = bpy.data.meshes.new(dst.name)
+            bm.to_mesh(dst.data)
+            collection.objects.link(dst)
 
         return {"FINISHED"}