The glass sphere not only has a spherical texture from the environment but also the incoming light and reflecting light.
For example, the backward objects emit light the pass the glass while the front object will be reflected on the sphere, so there is a combination of sources of lights.
A simple texture mapping might be ok for an opaque sphere, but not good enough for a transparent glass ball.
GuardHei
@CeHao1
It is actually possible to fake that light "emission" using only one spherical environment map. You just need to sample the opposite direction to fake the environment light coming from the back.
This is a common trick used in many mobile games, and this way you can fake transparent objects using opaque rendering techniques.
The glass sphere not only has a spherical texture from the environment but also the incoming light and reflecting light.
For example, the backward objects emit light the pass the glass while the front object will be reflected on the sphere, so there is a combination of sources of lights.
A simple texture mapping might be ok for an opaque sphere, but not good enough for a transparent glass ball.
@CeHao1
It is actually possible to fake that light "emission" using only one spherical environment map. You just need to sample the opposite direction to fake the environment light coming from the back.
This is a common trick used in many mobile games, and this way you can fake transparent objects using opaque rendering techniques.