Final Texture Color for normal vector = (0.4, 0.65, 1).

Let’s look at an example with a negative value: To convert our Tangent Normal Vector into a range that a texture can hold, we take the X and Y components and multiply them by 0.5, then add 0.5. Instead of performing a Remap() function, where we might pass in the negative to positive normal vector and get it remapped into a positive range, the math we use is a lot simpler than a Remap() function, since that uses a divide. Since our textures that store the tangent space normal vectors can only store positive values, but we want to also store negative values too, we need a way of remapping a negative to positive range into the positive range. We don’t just want the normal to deviate in this single quadrant though, we want a full range of coordinates around the normal. Which means, without performing any type of conversion, the minimum vector we could store would be (0,0,1) and the maximum would be (1,1,1) (ignoring the Z component in this example), which would look like it can only deviate a max of one quadrant area from the surface normal.

Our Tangent Space normal maps can only store positive values, whether it be from the range 0 - 1 or 0 – 255 (we will stick with the 0-1 range). You may have seen the coordinate (0,0,1) used as a default tangent space normal, and the Z component being 1 makes it align with the normal exactly. The normal of the vertex is colored purple, whilst the tangent space aligned axis has the Z component aligned with the normal. The X and Y component are also referred to as the Tangent and BiNormal (sometimes also called BiTangent). The X and Y components can be thought of as describing how much the surface normal deviates from its original direction.

We can think of tangent space as a relative axis conforming to the normal of a surface, where the Z component matches the surface normal’s direction. Tangent Space is another one of these spaces.

You’ve probably heard of spaces before with names like WorldSpace, ObjectSpace, ViewSpace, ScreenSpace, ClipSpace, etc. Or, in the case of setting the normal map texture to be imported as such, the Sample Texture 2D performs this function itself:īut why is it needed? Let’s start by looking at the space in these normal maps are made for, Tangent Space. Or in shadergraph, if you are using a normal texture without setting the texture import type as normal, you may have come across this node: When writing shaders, you’ve probably come across the function in shader code ‘UnpackNormal’, which can be seen in use here:įloat3 normal = UnpackNormal (tex2D(_Bump, _IN.uv_BumpMap))

Unpack unity3d