Use the items in this Menu to adjust how your model appears in the Viewport: Flat Shade, Wireframe, etc.,

Whether the 3D Grid or 2D Grid is displayed (along with its increment settings), whether the coordinate axes are displayed, whether Snap is activated for Brushing operations, to toggle between Perspective and Orthographic Views, and to toggle between a full screen interface display or the default display.

GGX, Burley 12 (UE4): GGX compatible with Unreal4, 4A Games pilpeline, Disney, Unity etc.
GGX, Lambert (Marmoset): GGX - compatible with Marmoset. It differs from regular GGX by lack off additional diffuse modulation.
Handpaint: The best for handpainted textures. This is GGX shader with zero specularity at rough plastic.

Greyscale Panorama: Use greyscale panoramas to avoid any color distortion.
Smooth Shade: Smooth shade (hotkey “5”).
Relief Only: Displays relief maps only, in the viewport.
Flat Shade: Displays a flat shaded view, in the viewport.
Gloss/Roughness only: Displays only your those maps, in the viewport.
Specular Color: Displays a Specular Color shaded view, in the viewport.
Metalness: Displays Metalness map only, in the viewport.

Backface Culling:
Linear Texture Filtering: Use linear texture filtering for color texture. Turn it off to get point filtering.
Turn Point filtering off is useful for precise painting and for pixel paint art style if you want to paint very small textures to replicate an art-style of fairly low-poly models with pixelated textures.

Wireframe: Show wireframe of the model.
Correct Alpha Ordering: To view semitransparent models correctly, we need to sort faces from back to front. Generally, it is a fast process, but if you feel that it slows rendering down, you may turn it off. Pay attention, alpha ordering works only for paint objects now.
Seams: Show seams edges over wireframe of the model.
Low-Poly: You can view and edit low-poly model with normal map.

Show 3D Grid: Turn on/off 3D-grid plane in 3D viewport.
Snap to 3D Grid: Snap cursor to the projection of 3D grid on screen. If several grids are visible the most rotated toward screen will be chosen. It is recommended to use it in orthogonal projection. Gizmos and primitives positions and size will be snapped to discrete positions in space.
Grid Placement:
Grid Density:

Axis:
Separate Axis:

Show 2D Grid: Show/Hide 2D Grid. Ctrl+'
Snap to 2D Grid: Snap the cursor to the grid. This is usually used in conjunction with the curve tools (Draw with spline, putting text on curve and putting picture along spline), with Snap to grid on, you can snap the points of the curve to the 2D-grid, then you can draw very exact shapes.
Snap to Low-Poly Vertices: Snap brush to low-poly mesh vertex positions. Sometimes helpful when you are retopologizing, or texturing.

Show Voxels in Paint Room:

Orthographic Projection: Toggle between perspective and orthographic projection
Toggle Full Screen:

Show Displacemenet mesh: Show actual mesh displacement. Vertices of the mesh will be displaced along the normal in correspondence with the displacement map.
Adjust Tesellation: You can improve visual appearance of mesh displacement using additional teeselation of faces. Face represented as a grid NxN over every face. Use this options only if you are sure that your video card can support the additional processing.
Load/Save Voxtree visibility states:

Grids, Workplanes & Axis Handles: This video demonstrates the usage of 3D Grids (including vertical Work Plane), 2D Grid, Axis Handles, setting units of measure, snapping, and storing 2D Grid changes with Camera Shortcuts. Some of the features presented are relatively new, in 3DCoat V4.

Grids, Workplanes & Axis Handles: This video demonstrates the usage of 3D Grids (including vertical Work Plane), 2D Grid, Axis Handles, setting units of measure, snapping, and storing 2D Grid changes with Camera Shortcuts. Some of the features presented are relatively new, in 3DCoat V4.