Houdini 20.5 Nodes VOP nodes

UV Planar Project VOP node

Computes UV co-ordinates projected along a single axis, derived from the position of an object, and generates a mask relative to the projection axis.

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Since 15.5

Overview

This node generates UV coordinates for a given point, based on projecting planar coordinates onto the geometry along a given axis.

For “hero” models, you will often put careful texture UVs on the geometry as attributes. However, it can be useful to generate quick UVs “on the fly” in the shader when precise texturing is not necessary. For example, you might generate UVs in a shader to wrap a rocky texture around a bunch of rocks in the scene.

Mask

This node also generates a mask value for the given point. This floating point value measures how perpendicular the surface was to the projection axis at the given point. This lets you only display a texture on the points facing toward the projection direction. Use the Axis Mask as the Bias input on a Color Mix VOP to blend between projected textures.

Negative axis

This node has separate UV and mask outputs for points that are “projected onto” (that face the projection axis), and points “facing away” on the opposite side of the model (based on the surface normal).

You can combine the positive and negative axis masks using a Maximum VOP if you want the projected texture to be the same in both directions.

Tips

  • If textures projected from the positive and negative directions clash at meeting points, you can use the Scale and Rotate controls to try to match them up.

  • The UV Triplanar Project VOP packages up three of these planar projections and blending nodes to do 3D planar projection mapping.

Parameters

UV Offset

Shifts the UVs generated by this VOP in the U or V direction. This can be useful when the VOP is used alongside other projections to help disguise texture repetition.

Axis

The axis to project the UV’s along.

Mask Sharpness

The mask value falls off linearly as the surface tails away from the axis of projection. Mask Sharpness allows you to control how soft or sharp the falloff is at the edge of the mask.

Positive axis

Scale

Scales the generated UVs. Higher values give more tiling in the projected texture.

Angle

Rotates the generated UVs. This can be useful for aligning textures to those projected from the negative axis.

Separate Axis Controls

Turn this on to get separate Scale and Angle controls for the negative axis.

Negative Axis

Scale

Scales the generated UVs facing away from the projection. Higher values result in more tiling in the projected texture.

Angle

Rotates the generated UVs facing away from the projection. This can be useful for aligning textures projected from the positive axis.

Outputs

Positive Axis UV (pos_uv)

The UV coordinates for the current point.

Negative Axis UV (neg_uv)

The UV coordinates projected from the opposite direction of the Axis. This is useful when the UV coordinates for the negative axis have been projected using separate Scale and Angle values from the positive axis coordinates.

Positive Axis Mask (pos_mask)

The mask value for the current point.

Negative Axis Mask (neg_mask)

The mask value for the projection from the opposite direction of the Axis.

See also

VOP nodes