ShengrenNiu

Results 2 issues of ShengrenNiu

It seems that pytorch3D only support the rasterized renderer. Will it support the ray-tracing method in the future version?

enhancement

`c_loss = tf.reduce_mean(fake_logit - true_logit)` maybe wrong. It should be `c_loss = tf.reduce_mean(fake_logit) - tf.reduce_mean(true_logit)`