This is an old revision of the document!
The Edit Surface Properties tool gives you control over the surfaces of Bezier patches and brush faces. You can use it to apply and change materials and modify their scale, shift and rotation on the surface. Sophisticated controls are available to determine these and other attributes of a surface.
The Edit Surface Properties tool can be activated by clicking on the related icon in the Tools toolbar or by pressing the SHIFT+A
shortcut key.
A normal click with the left mouse button on a surface (Bezier patch or brush face) in the 3D view accomplishes two tasks:
As usual, you can hold the CTRL
key to select more than one surface at a time.
Please note that CTRL
-clicked surfaces are selected, but not picked.
That is, only the first selected surface (left mouse button click without CTRL
) implies the pick operation.
In fact, selection and picking are actions that are independent of each other:
CTRL
key while clicking toggles the selection, but doesn't pick.ALT
key during the mouse click, which activates the eyedropper mode. The properties of such clicked surfaces will appear in the dialog, but their selection status won't change.
Finally, you can also hold the SHIFT
key during a left mouse button click.
The SHIFT
key does not add anything special when the click is on a Bezier patch,
but for brush faces, it causes all faces of the affected brush to become selected.
(If CTRL
is not held at the same time, the clicked brush face will also be picked for updating the dialog values.)
You can combine the SHIFT
with the CTRL
key in order to toggle the selection
status of all faces of the brush.
Brushes that were selected when the Edit Surfaces Tool was activated are automatically changed into face selections.
You can hide the reddish overlay of selected surfaces by checking the Hide Selection Overlay checkbox in the Tool Mode section of the dialog. This improves the visual perceptibility of the surfaces in some cases, which in turn can be helpful when using this tool.
Once you have selected one or more desired surfaces, you can modify their orientation and material attributes.
This is easily achieved by the appropriate controls of the related dialog. While pressing one of the small +
or -
buttons and choosing another material takes immediate effect, entering a new numerical value into the Scale, Shift or Rotation fields by hand requires an additional press on the RETURN
key to become effective.
If you have multiple surfaces selected at the same time, the new value of the changed attribute is applied to all of them, while all other attributes are left alone. This allows you for example to replace the material or to set a common scale on a number of surfaces all at the same time, while the individual shift, rotation and other surface aspects are left alone.
The orientation and material attributes in the dialog can also be applied to surfaces by right-clicking on them. The right-clicked surface needs not be selected for this to work, and all attributes (orientation and material) are applied at the same time. This feature makes the application of the attributes in the dialog to a number of surfaces quick and convenient.
With right-click application, the way in which the attributes are applied to the surfaces can be modified at the Right MB mode choice in the Tool Mode section of the dialog. The following options are available:
ALT
), the material is seamlessly aligned across the common edge. This is a worthwhile feature especially when the two surfaces are not coplanar. (It even works when the clicked surface is not immediately adjacent to the other.)
When SHIFT
is held during a right-click on a brush surface, the application is performed on all surfaces of the brush.
The button to all Sel. is equivalent to (but more convenient than) right-clicking on all currently selected surfaces with the current Right MB mode setting.
The materials of selected brush faces (not Bezier patches) can be automatically aligned at the top, bottom, left or right edge of the face by the related button in the Alignment section of the dialog. The material can also be centered or made fit on the brush face. In all cases, the effect is achieved by auto-adjusting the Shift and/or Scale attributes of the selected brush faces appropriately.
( The above applies to brush faces only. )
( Re-pick the first selected surface in order to update the dialog attributes! )
The Treat multiple as one checkbox determines whether multiple selected surfaces are treated, with regards to their spatial extends, as multiple individuals or as a single merged one when one of the Alignment buttons is pressed.
Note that for Bezier patches, the Fit button works a little differently than for brush faces: Although in both cases the material will be made “fit” on the underlying surface, Bezier patches are from then on in a different texture-coordinate generation mode than brush faces. This is because for brush faces, you could have achieved the same effect by manipulating the Scale and Shift manually until the result is identical. With Bezier patches, which can be curved to any shape (e.g. cylindrical or spherical), this is impossible.
As a result, the Bezier patches whose material is applied with the Fit button (a highly useful button with Bezier patches) puts them into a different texture-coordinate generation mode that is not compatible with that of brush faces: You cannot pick such Bezier patch surfaces and apply them directly to brush faces (but still to other Bezier patches), and – more importantly – the Scale attribute now indicates the number of repetitions of the material on the surface, rather than the number of texels per world unit as usual. The background of the Orientation attribute fields is colored in order to indicate that a Bezier patch surface has been picked that is in this special texture-coordinate generation mode.
You can “revert” the behaviour of such a Bezier patches surface by picking the surface attributes of a brush face and right-click applying them to the Bezier patch in Apply Projective mouse-button mode.
The wrt. World axes checkbox indicates whether the texture plane of the surface happens to be parallel to one of the three major planes through the world axes.
The wrt. Face plane checkbox indicates whether the texture plane of the surface is parallel to the spatial plane of the surface. This is never true for Bezier patches (they in general have no inherent spatial plane), and normally always true for brush faces; however you can use the Apply Projective right-click apply mode in order to force any texture plane onto any surface.
( Update code so that these are indeed indicators only. Move into Orientation section? )
It might happen that picking up surface properties (either by selecting or with the eye dropper tool) doesn't work and the message “Picking orientation values from objects with custom UVs is not possible.” appears on the screen. This means that the material is applied in a custom way and the dialog is not able to read definite orientation values from this surface. It is still possible to select such surfaces and apply new values to them, thus ending their custom state.
Another special case are bezier patches that are newly created or whose material is applied using the FIT button. In both cases the material is not plane projected onto the patch, but applied in a way only suitable for bezier patches. Picking up the properties of such a bezier patch results in blue colored orientation values. This shows that applying these values onto a face might have an unexpected result since these values have another meaning for fit applied bezier patches.
This graphic shows how textures are mapped onto faces. Note that the graphic shows a top down view, so the texture planes y axis is not visible in it.
Textures are mapped on a face by parallel projecting the texture from a texture plane P onto a face. The texture plane from which the texture is projected can be any plane in worlds coordinate system, but is usually chosen to be parallel to the face on which the texture should be projected (see faces of brushes A and D in the graphic).
In the texture plane, a point of origin is needed to determine where the first texture is drawn onto the plane. This point of origin is the normal vector from the plane to the world origin and therefore unique for every plane. Starting from this point the texture is tiled onto the plane whereat the length of the x axis vector is the textures width and the y axis vector (not visible in this graphic) is the textures height. The texture repeats itself along the x and y axis (see red dashes).
The vectors that decide the width and height of the texture can be increased or decreased in size to scale the texture. This is what happens when you increase or decrease the Scale value in the Edit Face Properties dialog (see above). The Shift values in the dialog are added as an offset the point of origin of the texture plane to shift the texture in x or y direction. The Rotation value is used to rotate the point of origin and in this way rotate the texture.
How a texture is projected onto a face depends on the position of the face in relation to the texture plane. In this example the face of brush A lies exactly in the dimensions of the x axis vector and therefore the texture fits exactly on the faces width. The face of brush D however lies outside the regular tiling of the texture plane and therefore the texture is mapped shifted onto the face starting at the first half of the textures x coordinates.
As said above the texture plane can be any plane in the worlds coordinate system. This results in texture planes that are not parallel to the face the texture is projected on. In this case the texture is projected in the same way as before, but the result is a contorted texture on the face due to the fact that a smaller texture area is mapped onto a bigger face area (see brushes B and C in graphic).
In the Edit Face Properties dialog the wrt. World axes and wrt. Face plane show if the texture plane of this face is parallel to the world axes or to the face plane. It is also possible to set these values and therefore explicitly set the texture plane to world axes or face plane.