Windwalkr: Created page with "Tangent Space is a specialized coordinate system used in fragment shading which can be considered as having the following properties: * Z points away from the surface (along..."

2017-10-19T00:24:19Z

Created page with "Tangent Space is a specialized coordinate system used in fragment shading which can be considered as having the following properties: * Z points away from the surface (along..."

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Tangent Space is a specialized coordinate system used in fragment shading which can be considered as having the following properties:

* Z points away from the surface (along the [[surface normal]]).
* X points approximately along the texture mapping "S" axis. (Approximate since the fragment normal is frequently not at 90° to the "S" axis.)
* Y points approximately along the texture mapping "T" axis. (Approximate since texture maps are frequently applied in a distorted fashion; ie. with the texture S and T axes not at 90° to each other.)

The Z axis is known as the "normal". The X axis is known as the "tangent". The Y axis is known as the "bitangent". It should be observed that Tangent Space is derived per-fragment, and varies across a rendered [[polygon]] based on the interpolation of the surface normal.

[[Normal map]]s are encoded in tangent space. To convert a single vector read from a normal space into model space, it is multiplied through the 'tangent basis matrix' (a matrix which encodes the tangent space axes). Tangent Space also affects other techniques such as [[Parallax mapping]].

More technical details on tangent space and the related math can be found online- this is not a Trainz-specific subject matter.

Tangent space - Revision history

Windwalkr: Created page with "Tangent Space is a specialized coordinate system used in fragment shading which can be considered as having the following properties: * Z points away from the surface (along..."