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What is tangent space normal map?
Tangent space. Normal vectors in a normal map are expressed in tangent space where normals always point roughly in the positive z direction. Tangent space is a space that’s local to the surface of a triangle: the normals are relative to the local reference frame of the individual triangles.
What is the tangent line of a vector?
Consider a fixed point X and a moving point P on a curve. As point P moves toward X, the vector from X to P approaches the tangent vector at X. The line that contains the tangent vector is the tangent line.
How to transform tangent space to object space?
To transform from tangent-space to object-space you need three things: Those three things together form the tangent-space -> object-space change of basis matrix (usually referred to as TBN because the vectors are called Tangent, Bitangent and Normal).
Is there such a thing as a normal space?
There are “normal spaces” in mathematics, but that is quite unrelated and there is no standard coordinate space referred to as “normal space.” My question is how to convert tangent to world. Your polygon’s world-space normal is inadequate to solve this problem (in fact, you need a per-vertex normal).
How are vectors transformed into tangent space in OpenGL?
Traditionally it is used to transform vectors into tangent-space, but you want to transform them out. The inverse of a rotation matrix is the same as its transpose, so all you really have to do is put those 3 vectors across your rows instead of columns 1.
Do you need normals to skip over object space?
However, you do not want object-space normals in this question, so you need to multiply that matrix by your model matrix so that it skips over object-space and goes straight to world-space. Likewise, if your normal vector is already in world-space you need to transform it back to object-space.