Spherical Normal maps

Normal maps are different between flat faces, Spherical prim faces and Sculpted Prims. Spherical prim faces require a rotation by 90° that can be tricky for some textures, like normal maps for spherical globes:

Planar sculpt maps work just fine on all PRIM_SCULPT_TYPE_SPHERE sculpted prims, but they do not work on prim spheres

3e9211d6-c42d-a9ff-95b9-5c1ab349ed38 will NOT work on prim spheres because they have their poles on the left and right side of an unrotated texture. But rotating a normal map changes the normal map, rotating a normal map by 180° inverts it.

Using .werkkzeug3 [1] to make maps for spherical prims from a height map needs the following command chain:

(double right klick in the lower window to add a function, they are chained from top to bottom loke these functions:)

• Import: (a .png height map image that has the north pole facing up and that has high parts white and low parts black)
• Rotate: With "angle" set to -0.250, rotating 90° to the right!
• Normal: 3d (flat will be red, hills are green on the lower side)
• HSCB: With 0.600 as "hue" parameter, making "flat" BLUE.
• Rotate: With "angle" set to 0.250, rotating 90° to the left.

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A PRIM_TYPE_SPHERE normal map for a sphere prim must be rotated by 90°:

but green must still be on the upper side of a hill like here: ab6adc27-e101-9d3a-1097-088104c1f607

Using .werkkzeug3 to make these normal maps for spherical prims needs the following command chain:

• Import: (a .png height map image that has the north pole facing up and that has high parts white and low parts black)
• Normal: 3d (flat will be red, hills are green on the lower side)
• Rotate: With "angle" set to 0.250, rotating 90° to the left.
• HSCB: With 0.600 as "hue" parameter, making "flat" blue.

This Purple-rotated normal map works on sculpt spheres and prim spheres, but not on flat prim faces:

1e266b9c-f842-865f-9eb2-39b43e30cb75 if good if you like spheres.

• Import: (a .png height map image that has the north pole facing up and that has high parts white and low parts black)
• Color: "Mode" set to "invert" (inverting the height map to make high places black and low places white)
• Rotate: With "angle" set to 0.250, rotating 90° to the left.
• Normal: 3d (flat will be red, hills are green on the lower side)
• HSCB: With 0.800 as "hue" parameter, making "flat" PURPLE. (0.8 is correct here, it is purple after all)

The normal map must be rotated by 270 in second life.