Normal matrix

[Shot]

Is there a way to send a normal matrix (transpose of inverse of model view matrix) to shader for every object in a scene?

[EgonOlsen]

You don't have to. I think the source of the shaders in the HelloShader example show what to do instead.

[Shot]

Yep, I saw it, but imho it's not correct because after this operation normal may not be prependicular to its' surface. See this explanation: http://www.lighthouse3d.com/tutorials/glsl-tutorial/the-normal-matrix/

[Thomas.]

Calculation normals from modelViewMatrix is faster and for orthogonal transformations it is fine (transpose and invert is about O(300))

[Shot]

I see, but what about non-orthogonal transformations? Is it a proper way of thinking: orthogonal camera == orthogonal transformations and perspective camera == non-orthogonal transformations?

[Thomas.]

No, non orthogonal transformation is for example scale in x axis