Ifc Text rotation in viewport preview

src/blenderbim/blenderbim/bim/module/drawing/decoration.py

@@ -30,7 +30,7 @@ from math import acos, pi, atan, degrees
 from functools import reduce
 from itertools import chain
 from bpy.types import SpaceView3D
-from mathutils import Vector, Matrix
+from mathutils import Vector, Matrix, geometry
 from bpy_extras.view3d_utils import location_3d_to_region_2d
 from gpu.types import GPUShader, GPUBatch, GPUIndexBuf, GPUVertBuf, GPUVertFormat
 from gpu_extras.batch import batch_for_shader
@@ -384,7 +384,7 @@ class BaseDecorator:
         context,
         text,
         pos,
-        dir,
+        text_dir,
         gap=4,
         center=True,
         vcenter=False,
@@ -409,9 +409,10 @@ class BaseDecorator:
 
         color = context.scene.DocProperties.decorations_colour
 
-        ang = -Vector((1, 0)).angle_signed(dir)
+        ang = -Vector((1, 0)).angle_signed(text_dir)
         cos = math.cos(ang)
         sin = math.sin(ang)
+        rotated_y_axis = Vector([-sin, cos])
 
         # Horrific prototype code
         factor = self.camera_zoom_to_factor(context.space_data.region_3d.view_camera_zoom)
@@ -423,7 +424,7 @@ class BaseDecorator:
         # font_size = 16 <-- this is a good default
         # TODO: need to synchronize it better with svg
         font_size_px = int(0.004118616 * mm_to_px) * font_size_mm / 2.5
-        pos = pos - Vector((0, line_no * font_size_px))
+        pos = pos - line_no * font_size_px * rotated_y_axis
 
         blf.size(font_id, font_size_px, dpi)
 
@@ -2074,11 +2075,48 @@ class TextDecorator(BaseDecorator):
     def decorate(self, context, obj):
         self.draw_labels(context, obj)
 
+    def project_point_onto_camera(self, point, camera_projection):
+        # TODO is this needlessly complex?
+        camera = bpy.context.scene.camera
+        return camera.matrix_world.inverted() @ geometry.intersect_line_plane(
+            point.xyz,
+            point.xyz - Vector(camera_projection),
+            camera.location,
+            Vector(camera_projection),
+        )
+
+    def get_camera_dimensions(self):
+        render = bpy.context.scene.render
+        camera = bpy.context.scene.camera
+        if render.resolution_x > render.resolution_y: # is_landscape
+            width = camera.data.ortho_scale
+            height = width / render.resolution_x * render.resolution_y
+        else:
+            height = camera.data.ortho_scale
+            width = height / render.resolution_y * render.resolution_x
+        return width, height
+
     def draw_labels(self, context, obj):
         region = context.region
         region3d = context.region_data
-        # TODO: support text rotation
+
-        dir = Vector((1, 0))
+        # TODO: optimize for realtime viewport render
+        # currently it's just copied from svgwriter
+        # to make rotation work in viewport
+        camera = bpy.context.scene.camera
+        camera_dimensions = Vector(self.get_camera_dimensions())
+        x_offset, y_offset = camera_dimensions / 2
+        position = obj.matrix_world.translation
+        camera_projection = tuple(
+            camera.matrix_world.to_quaternion() @ Vector((0, 0, -1))
+        )
+        text_position = self.project_point_onto_camera(position, camera_projection)
+        text_position = Vector(((x_offset + text_position.x), (y_offset - text_position.y)))
+        local_x_axis = obj.matrix_world.to_quaternion() @ Vector((1, 0, 0))
+        projected_x_axis = self.project_point_onto_camera(position + local_x_axis, camera_projection)
+        text_dir = (Vector((x_offset + projected_x_axis.x, y_offset + projected_x_axis.y)) - text_position)
+
+
         pos = location_3d_to_region_2d(region, region3d, obj.matrix_world.translation)
         props = obj.BIMTextProperties
         text_data = props.get_text_edited_data() if props.is_editing else DecoratorData.get_ifc_text_data(obj)
@@ -2104,7 +2142,7 @@ class TextDecorator(BaseDecorator):
                     context,
                     line,
                     pos,
-                    dir,
+                    text_dir,
                     gap=0,
                     center=False,
                     vcenter=False,