When no texture is loaded the light calculation is wrong

[kimkulling]

Describe the bug When a loaded model does not have any textures the texture calculation gets wrong.

To Reproduce Steps to reproduce the behavior:

1. Load obj box without texures
2. Check render result

Expected behavior Lightning applied

Screenshots

Desktop (please complete the following information):

• OS: All

Additional context N/A

[kimkulling]

Seems that we need to do the calculation of phong in the fragment shader: https://stackoverflow.com/questions/55778950/how-to-combine-texture-and-lighting-in-opengl