How to flip faces in blender

Normals¶

The Normal Edit Modifier can be used to edit normals.

The Weighted Normal Modifier can be used to affect normals by various methods, including Face Strength (see below).

You can also copy normals from another mesh using Data Transfer ( operator or modifier ).

Shading¶

Flat¶

As seen in the previous sections, polygons are central to Blender. Most objects are represented by polygons and truly curved objects are often approximated by polygon meshes. When rendering images, you may notice that these polygons appear as a series of small, flat faces. Sometimes this is a desirable effect, but usually we want our objects to look nice and smooth.

Smooth¶

The easiest way is to set an entire object as smooth or faceted by selecting a mesh object, and in Object Mode, select Shade Smooth in the Object menu. This forces the assignment of the “smoothing” attribute to each face in the mesh, including when you add or delete geometry.

Notice that the outline of the object is still strongly faceted. Activating the smoothing features does not actually modify the object’s geometry; it changes the way the shading is calculated across the surfaces (normals will be interpolated), giving the illusion of a smooth surface.

Select the Shade Flat item in the Object menu to revert the shading back (normals will be constant) to that shown in the first image above.

Smoothing Parts of a Mesh¶

Alternatively, you can choose which faces to smooth by entering Edit Mode, then selecting some faces and picking Shade Smooth from the Face Menu.

When the mesh is in Edit Mode, only the selected faces will receive the “smoothing” attribute. You can set faces as flat (removing the “smoothing” attribute) in the same way by selecting edges and picking the Shade Flat from the Face Menu.

The Auto Smooth option is a quick and easy way to combine smooth and faceted faces in the same object.

Face Strength¶

Another way to affect normals is to set a Face Strength on the faces of the model. The Face Strength can be either Weak, Medium, or Strong. The idea is that the Weighted Normal Modifier can be set to pay attention to the Face Strength as follows: when combining the normals that meet at a vertex, only the faces with the strongest Face Strength will contribute to the final value.

For example, if three faces meet at a vertex and have the face weights weak, medium, and strong, then only the normal associated with the strong face will be used to set the final result.

Tools¶

Flip Direction¶

This will reverse the normals direction of all selected faces. Note that this allows you to precisely control the direction (not the orientation, which is always perpendicular to the face) of your normals, as only selected ones are flipped.

Recalculate Normals¶

These tools will recalculate the normals of selected faces so that they point outside (respectively inside) the volume that the face belongs to. The volume does not need to be closed; inside and outside are determined by the angles with adjacent faces. This means that the face of interest must be adjacent to at least one non-coplanar other face. For example, with a Grid primitive, recalculating normals does not have a meaningful result.

Set From Faces¶

Set the custom normals at corners to be the same as the face normal that the corner is part of.

Rotate¶

Point to Target¶

A target is set by the keys:

The tool operation can be modified; if one of the following keys has been previously pressed:

Align A Then all normals will point in the same direction: from the center of selected points to the target. Spherize S Then each normal will be an interpolation between its original value and the direction to the target. Invert I Then the normal directions are reversed from what was specified above. Reset R Will reset the custom normals back to what they were when the operation started.

Merge¶

Merge all of the normals at selected vertices, making one average normal for all of the faces.

Split¶

Split the normals at all selected vertices so that there are separate normals for each face, pointing in the same direction as those faces.

Average¶

Average all of the normals in each fan of faces between sharp edges at a vertex.

Copy Vectors¶

If a single normal is selected, copy it to an internal vector buffer.

Paste Vectors¶

Replace the selected normals with the one in the internal vector buffer.

Smoothen Vectors¶

Adjust the normals to bring them closer to their adjacent vertex normals.

Reset Vectors¶

Put normals back the to default calculation of the normals.

Select by Face Strength¶

Use the submenu to pick one of Weak, Medium, or Strong. Then this tool selects those faces that have the chosen face strength.

Set Face Strength¶

Use the submenu to pick one of Weak, Medium, or Strong. Then this tool changes the Face Strength of currently selected faces to the chosen face strength.

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How to make all faces flip to the right/consistent direction?

What’s happening is that I have tried to flip the normals, inside and out, but there are always faces which have to be flipped!

Normals recalculated

If I flip them again, all faces get flipped and end up horrible and, not working at all. So how can I make all of the faces flip to the right direction?

7 Answers 7

TL;DR: Select all and press Shift N to Recalculate Normals ( Ctrl N in 2.7x and earlier).

I think this is problem you are having: some of the normals are always facing the wrong direction.

If you have the whole mesh selected when you flip normals then you are just toggling between the backwards faces and the correct faces, what faces are backwards. You are flipping the whole mesh, the correct parts will become backwards.

Whilst in Edit Mode, with the whole mesh selected, Recalculate the normals. That should fix the problem.
If recalculating the normals does not fix it, then you will have to go through your mesh and select only the faces that are backwards then flip normals.

You can use «make normals consistent»

To find out which direction ther normals are pointing at you can enable «normal» in the mesh display tab.

I guess you ticked backface culling in the Options Panel N in section Shading.

Check your normals again with the Normals display option ticked.

This image shows a cube with a single face removed, the normals should all point outwards. due to the deleted face all the faces with normals pointing backward are hidden. The faces with normal pointing in to the viewers direction are displayed.

The materials also have a backface culling option (in game mode).

Go to Edit Mode > Face Select then press A Select all > Recalculate Normals Shift + N

While the question is rather old and solved, it’s still an important and underestimated topic leading to other questions coming up, so i would like to add one approach i did not see in the available answers here, for completeness sake.

Normals (or the orientation of the faces) in Blender can be made visible in 2 ways, one way would be with little lines pointing outward from the middle of a face, specifically the face-normals, while it gives us the information we may need, it can be hard to see wrong directed normals on complex geometry and long stretched faces, if you are a bit zoomed out.

Here i would suggest the Face Orientation to help get an easier overview on where there are faces in the wrong direction. Front and back of the face become blue and red respectively to have a strong contrast and allow better visual identification.

While it is easier to spot with the Face Orientation it does not replace the Normals as those i compared were only the Face-Normals. But something that happens often is that we work on geometry and apply subdivision surface modifiers to name one that makes most obvious problems with wrong Normals, just to then have to find out that a face got turned for whatever reason.

So i would like to suggest to switch on Face Orientation at least once before giving up on surface problems, most likely if it turns out to be the Normals, the solution is underestimated easy.

Be it with recalculating Shift + N to let Blender figure out what’s in- and outside, or by selecting the wrong ones manually and flipping them with Alt + N selecting «Flip». One thing to keep in mind though, both functions need you to select the faces you want to affect!

How do I flip normals on this model? [duplicate]

This is probably too many questions at once but my time is short as the semester is coming to an end and I really want to work this issue out before my class time is over. Please humor me.

Yesterday I asked how to move the vertices so that they stitch together and got two answers that worked quite well. At first though selecting the vertices that I needed to move to the origin of the «Y» axis and scaling them to «zero Y» left a split with parallel lines of vertices because I had not set up my mesh exactly correct from the beginning of my modeling effort. When I moved the mesh so that they them moved to that «zero Y» point I found that I could not drag them accurately. I went a little beyond that point each time so I then scaled them again to «zero Y» and things looked better. It would help if I knew a way to accurately move the mesh to that point.

Today I find that I cannot flip the normals so that I can see the material on the mesh. Supposedly, according to the book I am using in class I can find it in the Mesh Tools while in Edit mode. That command may have been there in the release of blender that the text was written to, but it doesn’t appear in my 2.72 Blender.

I tried selecting all the vertices in Edit mode as directed and pressing «Ctrl-N» as directed, but all that did was make the normals appear to face the wrong way on both sides of the Mesh. Can you help with this? Also, Please tell me how to make Blender have only one screen after I have split it into two vertically. It is hard to get the Properties window to show up where I want it to be when I have two windows up.

Face Tools¶

These are tools that manipulate faces.

Fill¶

The Fill option will create triangular faces from any group of selected edges or vertices, as long as they form one or more complete perimeters.

Beauty Arrange the new triangles nicely.

Filled using fill.

Note, unlike creating n-gons, Fill supports holes.

A closed perimeter of edges with holes.

Filled using fill.

Beautify Faces¶

Beautify Faces works only on selected existing faces. It rearrange selected triangles to obtain more “balanced” ones (i.e. less long thin triangles).

Max Angle An angle delimiter option to limit edge rotation to flat surfaces.

Text converted to a mesh.

Result of Beautify Faces.

Grid Fill¶

Grid Fill uses a pair of connected edge loops or a single, closed edge loop to fill in a grid that follows the surrounding geometry.

The best predictable result can be achieved if you select two opposite edge loops with an equal number of vertices. When a single, closed edge loop is selected, the Span/Offset options allows you to adjust the way two opposite edge loops are detected from one closed edge loop.

Span Specifies the number of columns in the grid. Offset Defines the vertex that is considered to be the corner of the grid, by default, it’s the active vertex. The Offset allows you to rotate the grid lines. Simple Blending Use a simple interpolation algorithm to generate grid vertices from boundary loops, which doesn’t attempt to maintain the shape, useful for flat surfaces or times when keeping the shape gives odd results.

Grid Fill result.

Solidify¶

Thickness Amount to offset the newly created surface. Positive values offset the surface inward relative to the normals direction. Negative values offset outward.

Mesh before solidify operation.

Solidify with a positive thickness.

Solidify with a negative thickness.

Intersect¶

Intersect (Knife)В¶

The Intersect tool lets you cut intersections into geometry. It is a bit like Boolean Tool, but, does not calculate interior/exterior. Faces are split along the intersections, leaving new edges selected.

Source Selected/Unselected Operate between the selected and unselected geometry. Self Intersect Operate on the overlapping geometry of the mesh. Separate Mode All Splits the geometry at the new edge. Cut Keep each side of the intersection separate without splitting the faces in half. Merge Merge all the geometry from the intersection. Merge Threshold See Intersect (Boolean).

Intersect (Boolean)В¶

Performs boolean operations with the selection on the unselected geometry. While the Boolean Modifier is useful for non-destructive edits, access to booleans with a tool in Edit Mode can be useful to quickly perform edits.

Boolean Difference, Union, Intersect Swap Changes the order of the operation. Merge Threshold

Tolerance for close faces to be considered touching, It may be useful to increase this when some intersections aren’t detected that should be and when extra geometry is being created because edges aren’t detected as overlapping.

A threshold approaching size of faces may cause very slow calculation, in general keep this value small.

Wireframe¶

Poke Faces¶

Splits each selected faces into a triangle fan, create a new center vertex and create triangles between original face edges and new center vertex. The Offset can be used to make spikes or depressions.

Poke Offset Offset the new center vertex along the face normal. Offset Relative Multiply the Offset by the average length from the center to the face vertices. Poke Center

Computes the center of a face.

Weighted Mean Using the mean average weighted by edge length. Mean Using the mean average. Bounds Uses center of bounding box.

Triangulate Faces¶

Triangles to Quads¶

This tool converts the selected triangles into quads by taking adjacent triangles and removing the shared edge to create a quad, based on a threshold. This tool can be applied on a selection of multiple triangles.

This means you can select the entire mesh and convert triangles that already form square shapes – to be converted into quads, without having to concern yourself with individual faces.

Alternatively you can force this operation selecting a pairs of faces (see hint below for other ways of joining).

To create a quad, this tool needs at least two adjacent triangles. If you have an even number of selected triangles, it is also possible not to obtain only quads. In fact, this tool tries to create most even rectangular quads from the given triangles, which means some triangles could remain.

Before converting tris to quads.

After converting tris to quads.

All the menu entries and hotkeys use the settings defined in the Operator panel:

Max Angle This value, between (0 to 180), controls the threshold for this tool to work on adjacent triangles. With a threshold of 0.0, it will only join adjacent triangles that form a perfect rectangle (i.e. right-angled triangles sharing their hypotenuses). Larger values are required for triangles with a shared edge that is small, relative to the size of the other edges of the triangles. Compare UVs When enabled, it will prevent union of triangles that are not also adjacent in the active UV map. Compare Vertex Color When enabled, it will prevent union of triangles that have no matching vertex color. Compare Sharp When enabled, it will prevent union of triangles that share an edge marked as sharp. Compare Materials When enabled, it will prevent union of triangles that do not have the same material assigned.

Weld Edges into Faces¶

A tool to split selected faces by loose wire edges. This can be used in a similar way to the Knife tool, but the edges are manually setup first.

Rotate Edges¶

This tool functions the same edge rotation in edge mode. It works on the shared edge between two faces and rotates that edge if the edge was selected.

Two adjacent faces selected.

Selected edge rotated.

See Rotate Edge for more information.

Rotate & Reverse¶

Normals¶

See Editing Normals for more information.

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Symmetry

Всплывающее меню Симметрии

Tiling X,Y,Z— Использование этой опции позволяет вам плавно накладывать мазки вдоль заданных осей. Это позволяет создавать повторяющиеся узоры.

Options

Всплывающее меню Options в режиме Sculpting

Display:

Gravity:

Маски

— при нажатии на треугольник внизу справа появится дополнительные кисти.

Изменение прозрачности Масок в Overlays.

Кисть маска имеет такой же функционал, как и большинство кистей.

Brush Settings (Настройка Кисти):

— включить силу нажатия (для планшета).

— Использовать общий радиус для всех кистей, вместо отдельных радиусов на каждую кисть.

Advanced (Продвинутые настройки):

Auto-Masking (Автомаскирование):

Маскирование с учетом Топологии

Маскирование с учетом Face Sets.

Использование Mesh Boundary

Использование Face Sets Boundary

Маскирование с Включенным Front Face Only

Маскирование с Выключенном Front Face Only

Меню Mask

Помимо вышеперечисленных возможностей в меню Mask есть дополнительные.

Expand Mask By Topology (оригинал)

Expand Mask By Curvature (оригинал)

Использование Extract Mask

Использование Mask Slice

Использование Mask Slice and Fill Holes

Использование Mask Slice to New Object

Использование Dirty Mask.

Face Sets.

Пример использования Face Sets (оригинал)

Рисование Face Sets

Face Sets поддерживает сглаживание. Сглаживание происходит с сажатым Shift.

Сглаживание Face Sets

Что бы рисовать одним цветом зажмите Ctrl и начинайте рисовать в нужной цветовой области.

Рисование определенным Face Sets

Скрытие выбранного Face Sets

С включенным Автомаскированием по Face Sets в настройках кисти можно рисовать только на выбранной области.

Рисование с учетом Face Sets

Face Sets Boundary

Face Sets + Face Sets Boundary

Меню Face Sets

Маскирование Объектов.

Пример использования Fade Inactive Geometry