Modifying Vectors with Paint Blending Modes

Seven unique paint blending modes allow you to specify how the vectors are baked onto a model. These paint blending modes are not for exclusive use with the Vector Paint tool, but can also be used with the basic Paint tool. These modes are available in the paint blending mode dropdown menu in both the Paint and Vector Paint toolbars and the other paint tools, such as CloneStamp and Paint Through.

The Paint Flow Vectors and Paint Normal Vectors modes are an alpha blend between the vectors. The Nudge Flow Vectors and Nudge Normal Vectors modes add the vectors together to get the blend result. The paint flow and paint normal modes convert the painted vectors into the texture’s tangent space before creating the associated blend. This conversion takes into account the orientation of the texture on the model’s surface.

Note: Due to the fact that surface orientation plays such an important role, vectors baked down on a model may not be exactly the same as vectors painted. For example, a paint stroke from left to right on a model with a very high curvature may produce quite large changes in color when baked.

However, the Scale Vectors mode works differently to the above four modes. This mode uses the intensity of the color to control the length of the vector, and works best when painting in gray scale, with black representing short vectors, white representing long vectors, and gray being between the two. Paint Scale Vectors with the basic Paint tool.

The flow and normal vector modes refer to how the vectors are allowed to act in xyz space. Flow modes keep the vectors flat against the surface of the model. Normal modes allow the vectors to protrude outwards from the model in tangent z space. The type of vectors you want to paint may influence which paint blending modes you use. For example, flow modes are most often going to be used for flow maps, while you may prefer using normal modes for creating normal maps.

The Add Normal Maps and Mix Normal Maps modes blend two RGB-encoded vector layers with either the Add or Mix inputs and the Over input. Before the operation is performed the raw values are converted from the 0.0 to +1.0 colorspace-encoded range to the -1.0 to +1.0 vector range. The values are then added and normalized before converting back to the 0.0 to +1.0 colorspace-encoded range.

For more information on how to use these paint blending modes, see Paint Blending Modes in the section on Controlling the Way Mari Applies Paint to Your Model.

To adjust the paint blending mode, follow these steps:

With unbaked paint on your model, select one of the following modes from the Painting Mode dropdown menu:

• Paint Flow Vectors,

• Paint Normal Vectors,

• Nudge Flow Vectors,

• Nudge Normal Vectors,

• Scale Vectors,

• Add Normal Maps,

• Mix Normal Maps, and

• Mix Reoriented Normal Maps.

Selecting a paint blending mode can be done in either the Paint or Vector Paint toolbars, as the dropdown menu is in both. Alternatively, select them from the Painting Mode dropdown in the Painting palette.

Note: As with other paint blending modes, the vector modes apply to paint that has not been baked down yet.

To use a layered workflow, where you paint multiple layers of vectors and blend them together, the normal painting steps do not produce the results you might have expected, due to Mari's layers using premultiplied alpha. To blend a vector layer with the vector layer beneath it in the layer stack:

Create a new layer.

Fill it with a neutral vector color, thus making the layer opaque. A neutral vector color for normals is 0.5, 0.5, 1.0, and for flow it is 0.5, 0.5, 0.5, as described in more detail in Painting Vectors.

Paint on the new layer.

To blend with the layer below, add a layer mask and paint into it in order to show or hide the layer below.

Select a blend mode.

A layer's alpha values are no longer affected by premultiplied alpha and the vector blending results for your layers should now be correct.