This patch implements part of what was stated in {T66484}, with respect to `Base Point`.
## Introduction
The snapping feature of the transform tools has a variety of applications:
- Organization of nodes.
- Positioning of frames in precise time units.
- Retopology with snap to face
- Creation of armatures with bone positioning through the snap to volume
- Precise positioning of 3D or 2D objects in the surrounding geometry (CAD modeling)
The goal of this document is to make it more powerful for precision modeling and still supporting the old use cases without extra complexity.
The main topic addressed here is the introduction of a **interactive mode for setting a snap source** (See terminology).
## Terminology
* **Snap Source**: 3d coordinate * we want to snap from. (Currently defined by the `Snap With` options: `Closest`, `Center`, `Median` and `Active`).
* **Snap Target**: 3d coordinate* we want to snap to. (Vertices, Edges, Faces, Grid...)
## Interactive Mode for Editing a Snap Source
Currently the fixed snap point can only be obtained through the `Snap With` options. So it's a little tricky for the user to define a snap source point having so much geometry on an object.
Because of this, the user needs to resort to impractical solutions to get a point in the geometry.
See example of an impractical use:
{F11714181, layout=left, width=960, alt="The user used the cursor (which can be snapped) to choose the snap origin point."}
The user used the cursor (which can be snapped) to choose the snap source point.
While it is possible to work around this current limitation, it is important to reduce the number of steps and allow the user to set a snap source point through an optional interactive mode during a transformation.
The proposed solution is to be able to move the current snap source point through a modal modifier activated with a key (eg. B).
The snap source point can thus "snap" to the elements in the scene (vertex, mid-edge, Lamp, …) during this mode.
{F9122814, layout=left, width=960, alt="Base Point Snap, example of transform operation via the shortcut (not the tool). After pressing g and the snap base change shortcut (e.g., shift + ctrl) the user set the base point. The base point is then visible until the end of the operation. The z axis constrains the final position."}
## Implementation Details
- The feature will only be available in 3D View.
- The feature will only be available for `Move`, `Rotate` and `Scale` transform modes.
- The snap source editing will be enabled with a single click on the modifier key (B).
- Having a snap point indicated, the new snap origin point will be confirmed with the same buttons that confirms the transformation (but the transformation will not be concluded).
- The snap source editing can be canceled with the same key that activated it (B).
- If the transformation is done with "release_confirm" (common for gizmos), the new feature cannot be enabled.
- During the transformation, when enabling the feature, if the snap option is turned off in the scene, the snap will be forced on throughout the rest of the transformation (unless interactive mode is canceled).
- During a transformation, if no snap target is set for an element in the scene (Vertex, Grid...), the snap targets to geometry Vertex, Edge, Face, Center of Edge and Perpendicular of Edge will be set automatically.
- Snap cannot be turned off during the snap source editing.
- Constraint or similar modification features will not be available during the snap source editing.
- Text input will not be available during the snap source editing.
- When adding multiple snap points (A) the new prone snap source point will be indicated with an "X" drawing.
{F11817267}
Maniphest Tasks: T66484
Differential Revision: https://developer.blender.org/D9415
Move most of the gizmo snap and placement code to `view_cursor_snap.c`.
Simplify and extend the snap API.
Differential Revision: https://developer.blender.org/D12868
Regression introduced in {rBb0d9e6797fb8}.
Previously the Graphics Editor had a conflict with two different snap
types. Auto-Snap and Snap with Ctrl.
It is now clearer which snap should prevail.
Implements T89789, T89792, custom grid (described as dynamic grid in
T78389) and UV grid snapping (T78391)
Replaces the default UV editor grid with 2 new types of grid :
* Custom grid: Allows the user to create an NxN grid, where the value
of N is specified by the user.
* Subdividing grid: Subdivides the UV editor grid when the user
zooms in the viewport and vice versa when zooming out.
UV snapping improvements :
* Increment snapping: Increment values for snapping are calculated based
on which grid type is being used in the UV editor
(subdividing or custom). In general the increment value is equal to
the distance between 2 visible grid lines.
* Absolute grid snap: New toggle added to increment snapping option in
the UV editor, allows UV grid snapping during translation.
Reviewed By: campbellbarton
Ref D12684
Address initial feedback:
- Use checkboxes instead of radio buttons
- Hide snapping distance control from UI
- Tweak snapping line color - use selected strip color, 50% transparency. Similar to other editors
- Draw 2px thick line, since strip outline is also 2px thick
Reviewed By: HooglyBoogly
Differential Revision: https://developer.blender.org/D11759
Change snapping behavior to snap strip edges when they are close to snap point.
Default behavior is, that each transformed strip is snapped to any other strip.
Implement snapping controls in sequencer tool settings. These controls include:
- Snapping on/off
- Ability to snap to playhead and strip hold offset points
- Filter snap points by excluding sound or muted strips
- Control snapping distance
Snapping controls are placed in timeline header similar to 3D viewport
Reviewed By: mano-wii
Differential Revision: https://developer.blender.org/D11646
Use const arguments to simplify further optimizations.
Transforming elements shouldn't need to change their containers
data-structures.
ElementResize for grease pencil stroke thickness was
modifying TransInfo.num & TransInfo.values_final.
Now copies are operated on to preserve const correctness although
it's worth investigating if this can be avoided altogether.
The code takes many turns to get a suitable "target" for the snap to grid.
Perhaps there were other reasons awaited for `transformCenter_from_type`
and `TransCenterData center_cache[5]`.
But since nothing is defined, it is better to simplify the code.
No user functional changes
Individual projection is a different branch of snap and always projects
the transformed elements on the surface of objects.
Perhaps this option should be limited to the Move mode due to similarity.
But in order not to change the current behavior too much, this commit only
disables this option in modes not affected by snap.
The incremental snap was always operating in the local space, which in most
cases is the VIEW type orientation.
Use only local space when the operation is affected by constraint.
Differential Revision: https://developer.blender.org/D10052
Now we have a better distinction of what is snap to grid and what is
snap to increments.
The code also allows the implementation of mixed snap for these modes.
