Calculating the transformed normal of a mesh vertex

Troubleshooting General Help
1

Hi there,
I’m currently trying to build my own lighting system (Phong) and have some trouble with the normals I need for the calculation.
I know I can get the world coordinates of each vertex by applying the spatials world transformation to it, but as far as I know I need the inverse transpose matrix for the normals.
So now I’m a bit lost with the transform object I get via getWorldTransform, is it possible to get the transformed normal with this one or is my idea of doing it already wrong?
Thanks in advance for any help!

2

You could try:
http://hub.jmonkeyengine.org/javadoc/com/jme3/shader/UniformBinding.html#WorldMatrixInverseTranspose

Edit: and make sure to multiply only for rotation… so leave the 4th component of the vector 0.0 instead of 1.0.

Is there a reason you are writing your own lighting instead of just dismantling the existing phong lighting shader?

3

Hey, thanks for your answer, so I guess I need to take a look at the shader tutorial before trying this…
I have to do this for university, so just dismantling the existing one won’t count. :wink:

4
@irreparabel said: Hey, thanks for your answer, so I guess I need to take a look at the shader tutorial before trying this... I have to do this for university, so just dismantling the existing one won't count. ;)

Well, you should at least look at it so you how values are configured, I guess. Or maybe the shader tutorial covers the global bindings already.

Edit: note: JME’s lighting shader does lighting in view space… if you were also doing lighting in view space then you could also use the pre-existing NormalMatrix.