The thing that you want to look at it is: "How do your grades and SAT scores compare with the other students in your high school who apply to UCSB?" You will be compared to the other kids in your school. So, you if you have a 3.5, but if the average GPA of students who apply from your school is 4.0, then you may have a problem. On the other hand, if you have a 3.5 GPA and the average GPA of kids applying from your HS is 3.4, then that places you in a better position.
My son was admitted from the waitlist with an SAT score of 1950, ACT of 29, 8 AP classes and a GPA of 3.9 and lots of ECs. 135 kids applied from his HS (35 were accepted) and the average accepted GPA was 4.1. When he got to orientation, he found that kids from other schools had a GPA of 3.5 and had taken only 1 AP class.
Your GPA will be calculated for admission from the A-G classes that you took in your Sophmore and Junior years. They will take your weighted GPA from these 2 years in those classes.
One boy from my son's class had a 4.3, tons of APs and an ACT of 32 as well as perfect scores on the SAT2 in Chemistry, Physics and Calculus among others. He was in the top 5% of the class of 450. This is a high performing school, so when he applied to MIT, Dartmouth, Carnegie-Melon, etc. he was competing with 5 other students who were just like him and those schools only took ONE student from the school. He did not get into any of his first choice schools. He ended up at Berkeley, but it was his back-up school.
You can also plug your stats in on the college board website for UCSB and you can see where you fall on the spectrum. Try to get your test scores up as the UCs place alot of weight on GPA and test scores. Good Luck
Also....write a killer essay.