Live previews on every shader node

Hover probe Strip icon, or hold D over any preview

Shows the exact value under the cursor, with a dot on the sampled point. With the icon on it reads live while you hover; D works on any preview while the key is held, and a click copies the value. Vectors are shown as a pair, for example (0.31; -0.10). On the sphere and the mesh the value comes from the surface point under the cursor.

Out-of-range ShiftS

Paints red where the value goes above 1 and blue where it drops below 0. The quickest check for masks, roughness, height and displacement data that should stay inside 0–1.

Min / Max ShiftM · panel button

Prints the lowest and highest value under the thumbnail. When a UV channel is isolated the labels say what they measure, for example max U.

Histogram

A strip under the preview showing how the values are distributed, with min, max, mean and the share of clipped pixels. A mask that never reaches 1.0 is obvious in a second.

Heatmap

Replaces grey with a false-colour ramp from the minimum to the maximum and adds a legend. Small differences that are invisible in grey become clear bands.

Contour

Turn it on, then click the thumbnail: the value under the cursor becomes the threshold and its contour line is drawn across the preview. Hold and move to scrub the threshold live. Handy for placing a Color Ramp stop or checking where a mask cuts.

Split vector ShiftV

Shows one channel of a vector or colour output as its own preview. The icon cycles X → Y → Z → off; with split on, AltShift double-click on the right or left half of the thumbnail steps to the next or previous channel. The value tools then read that one channel.

Scalar mode Side panel › Inspect Values

How a vector becomes one number for Out-of-range, Heatmap, Contour, Histogram and Min/Max: Luma (brightness), Vector Length (magnitude, useful for displacement and normal vectors) or Normal Changes (how far it differs from the original direction). It appears when one of those tools is on and split is off.

Coordinate Checker

Feeds the node's output into a grid texture instead of showing it as colour. Stretching, seams, rotation and mirrored islands become visible.

Color Grid (on by default) uses Blender's lettered colour tiles, so a rotated or mirrored patch is obvious. Switch it off for plain squares and set how many fit across 0–1 with Squares.

If the node reads the camera direction (Camera Data, Fresnel, Layer Weight, or Geometry › Incoming), the panel warns that the grid moves when you orbit. That movement is real, not a bug.

UV Space

Flattens the evaluated mesh into its UV layout and draws the live shader across it. The 0–1 square is always framed, and islands that leave it stay visible. Switching UV Space off returns to the object you were on before.

The flattened copy has different positions and normals, so nodes that read Geometry, Object Info, Tangent, Bump and similar inputs show something else here. The panel lists them when that happens.

Channels: Both · U · V

With the Checker on, the value tools read the coordinate itself. Both gives a vector probe and a two-ramp heatmap (U red, V green). Pick U or V to isolate one channel at full precision; Contour, Histogram and Min/Max come back. The switch only appears once a value tool is on.

Stretch Mesh or UV Space

Is the coordinate spread evenly over the surface? It is measured per unit of real surface, with the tilt of the surface towards the camera corrected, and shown as an overlay with a legend of real multiples. Two measures:

Density: how fast the coordinate changes. Blue where the pattern smears (sparse), red where it crowds, grey at ×1, which is this field's median.

Anisotropy: shape rather than area. Grey where a square stays square, red where it is stretched one way. A grid of coordinate squares is drawn on top so you can see how they smear. A coordinate can pass the density check at ×1.03 and still be made of 30:1 slivers.

The hover probe reads the measure directly, for example density ×2.0 or aniso ×3.4. On the Mesh, Stretch always uses the orthographic camera because perspective would distort the measurement. In UV Space the mesh's own UV distortion is folded in.

Pin a preview

The pin icon anchors a thumbnail to the editor window. It stays on screen and keeps updating while you work at the other end of the tree. Drag it with the move icon, and use the fold icon to shrink its strip to fold, pin and move. Pinned previews and their icons are always drawn on top. Click the pin again to put it back on its node.

Solo Double-click a thumbnail

Enlarges the preview in place and draws it over everything else. Double-click again to restore it.

Fade and outline the active chain Preferences

Select a node and the previews that aren't connected to it fade out, while its chain stays at full strength. A coloured border marks previews inside the chain (green) and outside it (red). Both can be turned off or recoloured, and the fade strength is adjustable.

Arrange nodes Side panel › Tree · right-click menu

Lays the tree out in clean columns and leaves room for every thumbnail, so previews never overlap nodes. Arrange All handles the whole tree, Selected only the selected nodes. The right-click menu offers Arrange Nodes and Arrange Nodes + Reroutes.

With Add Reroutes, links that jump across columns run along a straight horizontal lane, and links leaving the same socket share one reroute. Reroutes you gave a label, and reroutes grouped in a frame of their own, are left alone. After running it, the redo panel (F9) adjusts the horizontal and vertical gaps. Arrange is a normal undo step.

Show, hide, disable

The eye button on a node toggles its own preview. CtrlH toggles the previews of all selected nodes. CtrlE disables every preview and stops rendering altogether; press it again to bring them back. In Preferences, Previews Visible by Default decides whether new nodes start with a thumbnail.