Added 'align selected face with buildplate' feature.

Alt-click to select a face. See the (identically named) 'feature_bottom_face' branch in Uranium for more indepth information.

cura/CuraActions.py

@@ -7,11 +7,13 @@ from typing import List, cast
 
 from UM.Event import CallFunctionEvent
 from UM.FlameProfiler import pyqtSlot
+from UM.Math.Quaternion import Quaternion
 from UM.Math.Vector import Vector
 from UM.Scene.Selection import Selection
 from UM.Scene.Iterator.BreadthFirstIterator import BreadthFirstIterator
 from UM.Operations.GroupedOperation import GroupedOperation
 from UM.Operations.RemoveSceneNodeOperation import RemoveSceneNodeOperation
+from UM.Operations.RotateOperation import RotateOperation
 from UM.Operations.TranslateOperation import TranslateOperation
 
 import cura.CuraApplication
@@ -73,6 +75,36 @@ class CuraActions(QObject):
             operation.addOperation(center_operation)
         operation.push()
 
+    # Rotate the selection, so that the face that the mouse-pointer is on, faces the build-plate.
+    @pyqtSlot()
+    def bottomFaceSelection(self) -> None:
+        selected_face = Selection.getSelectedFace()
+        if not selected_face:
+            Logger.log("e", "Bottom face operation shouldn't have been called without a selected face.")
+            return
+
+        original_node, face_id = selected_face
+        meshdata = original_node.getMeshDataTransformed()
+        if not meshdata or face_id < 0 or face_id > 0x10001:
+            return
+
+        rotation_point, face_normal = meshdata.getFacePlane(face_id)
+        rotation_point_vector = Vector(rotation_point[0], rotation_point[1], rotation_point[2])
+        face_normal_vector = Vector(face_normal[0], face_normal[1], face_normal[2])
+        rotation_quaternion = Quaternion.rotationTo(face_normal_vector.normalized(), Vector(0.0, -1.0, 0.0))
+
+        operation = GroupedOperation()
+        for node in Selection.getAllSelectedObjects():
+            current_node = node
+            parent_node = current_node.getParent()
+            while parent_node and parent_node.callDecoration("isGroup"):
+                current_node = parent_node
+                parent_node = current_node.getParent()
+
+        rotate_operation = RotateOperation(current_node, rotation_quaternion, rotation_point_vector)
+        operation.addOperation(rotate_operation)
+        operation.push()
+
     ##  Multiply all objects in the selection
     #
     #   \param count The number of times to multiply the selection.

plugins/SolidView/SolidView.py

@@ -139,6 +139,10 @@ class SolidView(View):
                             shade_factor * int(material_color[5:7], 16) / 255,
                             1.0
                         ]
+
+                        # Color the currently selected face-id, 0x10001 is certain to be greater than the largest ID.
+                        face = Selection.getSelectedFace()
+                        uniforms["selected_face"] = 0x10001 if not face or node != face[0] else face[1]
                     except ValueError:
                         pass
 

resources/qml/Actions.qml

@@ -26,6 +26,7 @@ Item
 
     property alias deleteSelection: deleteSelectionAction;
     property alias centerSelection: centerSelectionAction;
+    property alias bottomFaceSelection: bottomFaceSelectionAction;
     property alias multiplySelection: multiplySelectionAction;
 
     property alias deleteObject: deleteObjectAction;
@@ -271,6 +272,15 @@ Item
         onTriggered: CuraActions.centerSelection();
     }
 
+    Action
+    {
+        id: bottomFaceSelectionAction;
+        text: catalog.i18nc("@action:inmenu menubar:edit", "Align Selected Face To Bottom");
+        enabled: UM.Controller.toolsEnabled && UM.Selection.hasFaceSelected;
+        // iconName: "NO-ICON-YET"; // TODO?
+        onTriggered: CuraActions.bottomFaceSelection();
+    }
+
     Action
     {
         id: multiplySelectionAction;

resources/qml/Menus/ContextMenu.qml

@@ -20,6 +20,7 @@ Menu
     // Selection-related actions.
     MenuItem { action: Cura.Actions.centerSelection; }
     MenuItem { action: Cura.Actions.deleteSelection; }
+    MenuItem { action: Cura.Actions.bottomFaceSelection; }
     MenuItem { action: Cura.Actions.multiplySelection; }
 
     // Extruder selection - only visible if there is more than 1 extruder

resources/shaders/overhang.shader

@@ -32,6 +32,8 @@ fragment =
 
     uniform lowp float u_overhangAngle;
     uniform lowp vec4 u_overhangColor;
+    uniform lowp vec4 u_faceColor;
+    uniform highp int u_faceId;
 
     varying highp vec3 f_vertex;
     varying highp vec3 f_normal;
@@ -58,7 +60,7 @@ fragment =
         highp float NdotR = clamp(dot(viewVector, reflectedLight), 0.0, 1.0);
         finalColor += pow(NdotR, u_shininess) * u_specularColor;
 
-        finalColor = (-normal.y > u_overhangAngle) ? u_overhangColor : finalColor;
+        finalColor = (u_faceId != gl_PrimitiveID) ? ((-normal.y > u_overhangAngle) ? u_overhangColor : finalColor) : u_faceColor;
 
         gl_FragColor = finalColor;
         gl_FragColor.a = 1.0;
@@ -99,6 +101,8 @@ fragment41core =
 
     uniform lowp float u_overhangAngle;
     uniform lowp vec4 u_overhangColor;
+    uniform lowp vec4 u_faceColor;
+    uniform highp int u_faceId;
 
     in highp vec3 f_vertex;
     in highp vec3 f_normal;
@@ -127,7 +131,7 @@ fragment41core =
         highp float NdotR = clamp(dot(viewVector, reflectedLight), 0.0, 1.0);
         finalColor += pow(NdotR, u_shininess) * u_specularColor;
 
-        finalColor = (-normal.y > u_overhangAngle) ? u_overhangColor : finalColor;
+        finalColor = (u_faceId != gl_PrimitiveID) ? ((-normal.y > u_overhangAngle) ? u_overhangColor : finalColor) : u_faceColor;
 
         frag_color = finalColor;
         frag_color.a = 1.0;
@@ -138,6 +142,7 @@ u_ambientColor = [0.3, 0.3, 0.3, 1.0]
 u_diffuseColor = [1.0, 0.79, 0.14, 1.0]
 u_specularColor = [0.4, 0.4, 0.4, 1.0]
 u_overhangColor = [1.0, 0.0, 0.0, 1.0]
+u_faceColor = [0.0, 0.0, 1.0, 1.0]
 u_shininess = 20.0
 
 [bindings]
@@ -148,6 +153,7 @@ u_normalMatrix = normal_matrix
 u_viewPosition = view_position
 u_lightPosition = light_0_position
 u_diffuseColor = diffuse_color
+u_faceId = selected_face
 
 [attributes]
 a_vertex = vertex