This page provides information on the V-Ray UV projection node.
Overview
The V-Ray UV projection VOP allows you to use projection mapping for textures in a V-Ray shading network.
Advanced support for deforming and/or animated geometry is provided through the "rest" and "rnml" input sockets, expecting a V-Ray User Color VOP that samples pre-configured rest attributes on the rendered geometry.
Parameters
Type – Specifies the type of projection mapping to use from the following:
Disabled – No UV coordinates for projection are generated. The expected result is for pixel color at the (0, 0) coordinates of the input texture to be sampled and applied uniformly across the entire shaded surface.
Planar – The input texture is projected from an imaginary planar surface, facing towards the negative Z axis.
Spherical – The input texture is projected from an imaginary spherical surface. Additional control over the projection is provided through the U Angle and V Angle parameters.
Cylindrical – The input texture is projected from an imaginary cylindrical surface. Additional control over the projection is provided through the U Angle parameter.
Ball – The input texture is wrapped around the surface similar to the Spherical type – the benefit of this mapping type is that the texture is projected such that only a single pinch-point is present at the negative Z axis where the UVs converge, in contrast to the two pinch-points resulting from a typical Spherical UV projection.
Cubic – The input texture is projected inwards towards the surface, from all six sides of an imaginary box.
Tri-Planar – The equivalent of three Planar projections, one for each axis. The benefit of this mapping type compared to the Cubic projection is that it produces uniformly-sized UV scaling, whereas the Cubic type produces distortions for very tall/slim/narrow objects (unless manually resolved by scaling the Cubic projection using a V-Ray Transform Matrix VOP).
Perspective – The input texture is projected towards the surface from the camera provided under the Projection Camera parameter.
To control the orientation of the projections, use a V-Ray Transform Matrix VOP plugged into the "uvw_transform" input socket.
Projection Camera – Specifies the 'vanilla' Houdini /obj camera to use for the Perspective projection.
Projection Camera (LOP) – Specifies the Solaris /stage camera to use for the Perspective projection.
Texture Fit – Provides control over the texture scaling for the Perspective projection type.
None – The image is kept uniformly scaled, and one of its axes is resized proportionally to the camera settings aspect ratio (based on the Fit Fill settings) to fit it inside the camera view.
Match Camera Film Gate – The image is squeezed to fit into the camera view.
Match Camera Resolution – The image is scaled to match the camera resolution.
Camera Fill – If the Texture Fit is set to None, allows you to select the axis of the provided image that will be used to fill the camera view.
Fit Fill – The texture is scaled uniformly to fill the camera view.
Horizontal – The X axis is used when determining how to project the texture in the camera space.
Vertical – The Y axis is used when determining how to project the texture in the camera space.
U/V Angle – Only used for the Spherical and Cylindrical projection mapping types. Provides control over the number of texture repetitions.
Film Gate W/H – When Fit Type is set to Match Camera Film Gate, these parameters specify the Width and Height of that Film Gate.
Hide Backface – When using the Perspective projection type, disables projection over back-facing polygons (i.e. faces whose normals point away from the camera).
Hide Occluded – When using the Perspective projection type, disables projection over occluded geometry.
Object Space – When enabled, the projection is applied in the object space of the currently shaded geometry. This means that object-level transformations applied over the node will affect the scale and/or orientation of the projection.
Use Reference Points – When enabled, V-Ray will either expect a Reference Mesh attached to the geometry (through the V-Ray Object Properties), or a V-Ray User Color VOP sampling a set of rest position and normal attributes plugged into the respective input sockets of this VOP node. This is intended for deforming, animated geometry – the benefit is that the projection will be locked to the "rest" geometry, even when the surface is animated.