I am in the shader language with Webgl and GLSL.
I saw a tutorial on a normal matrix and I do not really understand it.
I mean, I think I agree with the calculations such as:
modelViewMatrix = mat4.multiply (camera.view, modelMatrix); inverseModelViewMatrix = mat4.invert (this.modelViewMatrix); normalMatrix = mat3.fromMat4 (inverseModelViewMatrix); normalMatrix = mat3.transpose (this.normalMatrix);
But why do I need it? Where can I find a case where I can see the difference between using it and not using it? Ot when do not I need it?