Same subject, use subjunctive with "si"?

Question

In this example we have the same subject in both clauses, but still use the subjunctive:

Te pondrías muy triste si me vieras sufrir.

Is this because "si" is used? Would it still use the subjunctive if we use "que" in the above sentence?

Thanks.

Accepted Answer

Hola Marcos
With this specific sentence you would need the infinitive, not a que clause, in order to make sense. 
Te pondrías muy triste si me vieras sufrir.
Te pondría muy triste verme sufrir. 
To use "que" it would have to change to:
Te pondría muy triste que yo sufriera. 
But this is to do with the nature of this sentence. For other sentences you can replace si with que, for example:
Me encantaría que vinera Carlos.
Me encantaría si viniera Carlos. 
Saludos
Inma