How do I align the UVW_Modifier's Gizmo to a selected face?

new.gif MAXScript Frequently Asked Questions


The following code implements the "Normal Align" feature of the UVW_Map modifier. The "Normal Align" button is not directly accessible to MAXScript. This function can be used as a replacement, and might help you understand the usefulness of the Vector Cross Product.


fn alignUVGizmo theObj theFace =


-- First get the face normal vector.

-- It is shown in BLUE on the image

faceNormal = in coordsys theObj (getFaceNormal theObj theFace)


-- This is the desired up vector in world space

-- It is shown in YELLOW on the image

worldUpVector = [0,0,1]



-- Now get the cross-product of the face normal and the up vector.

-- This will give you a vector that is perpendicular to the plane defined

-- by the normal and the up vector. Normalize it to get a normal vector

-- pointing to the right.

-- It is shown in RED on the image

rightVector = normalize (cross worldUpVector faceNormal)


-- Now using the face normal and the new vector,

-- get a vector that is perpendicular to the plane defined by the two.

-- This is the "local up vector", the vector that is the projection of

-- the world up vector on the face you selected. This one is perpendicular

-- to both the face normal and the right vector, and you have 3 normals now

-- that define the X, Y and Z of your new orthogonal coordinate system

-- for the UVW gizmo!

-- Note that this new vector can be seen as the SHADOW of the World Up vector

-- on the face of the object in the above image.

-- It is now displayed in green in the image below:

upVector = normalize ( cross rightVector faceNormal )


-- Using the 3 vectors, define a matrix3 value which represents the

-- coordinate system of the gizmo. The face normal is the Z axis,

-- the right vector is the X axis, and the local up vector is the Y axis:

theMatrix = matrix3 rightVector upVector faceNormal [0,0,0]


theMap = Uvwmap()

modPanel.addModToSelection theMap ui:on

theMap.gizmo.transform = theMatrix



See also

Point3 Values - Vector Cross Product


Frequently Asked Questions