Ensure the normals, texcoords, and tangent values for soy.bodies.Slider are correct and fix them where they are not.
Tangents previously pointed "up" (Y axis), where normals stick "out" (Z axis). With the new bumpmapping code, tangents must point "right" (X axis) and rotated 90 degrees from the normal.
Since our classes were written by different developers at different times, and bumpmapping is one of the least tested features, different classes are in different states - some texcoord/tangent data may be missing entirely while some may be already perfectly correct and need to just be checked over.
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When you've done, commit your work and post the resulting changeset url to this task.