<p>V-sync means that the GPU won't switch buffer until the current frame is done showing. </p>

<p>When you tell to swap the buffer with V-Sync enabled the actual swap doesn't happen until V-Blank, a small window between frames where nothing is being sent to the screen.</p>

<p>The reason I think you cannot see the update tear is that it moves across the screen during the update. While a non v-sync tear stays in the same place on the screen for 16 milliseconds.</p>

CC BY-SA 3.0
2016-04-06T09:00:12.287Z
Yes, I heard triple buffer technology. That's cool. Thanks.
Hao Zhang
CC BY-SA 3.0
2016-04-05T09:18:37.017Z
2016-04-05T09:18:37.017Z
ratchet freak
<p>1) Update the front buffer will cause screen tearing, every one knows it.</p>

<p>2) But V-Sync, I think it still get the same issue. Why I get this idea? </p>

<p>2.1) When GPU flips to the back buffer, current screen displays the old image which was in previous front buffer.</p>

<p>2.2) Now GPU sends image from "current front buffer" (previous back buffer) to monitor. This will last 16.7ms (60Hz). During this period, Human eyes will see half "current front buffer" and half "previous front buffer". Is it right?</p>

<p>2.3) If it is right, it would be same as non-V-sync.</p>

<p>3) But, in fact, when I switch "V-sync" on, I can't see screen tearing. Why?</p>

<p>Thanks a lot for the answers.</p>

<rendering><gpu>
Can V-Sync avoid tearing? I think it can't. Am I wrong?
Hao Zhang
# Can V-Sync avoid tearing? I think it can't. Am I wrong?

(Asked by: username_0 on 2016-04-05)

1) Update the front buffer will cause screen tearing, every one knows it.

2) But V-Sync, I think it still get the same issue. Why I get this idea?

2.1) When GPU flips to the back buffer, current screen displays the old image which was in previous front buffer.

2.2) Now GPU sends image from "current front buffer" (previous back buffer) to monitor. This will last 16.7ms (60Hz). During this period, Human eyes will see half "current front buffer" and half "previous front buffer". Is it right?

2.3) If it is right, it would be same as non-V-sync.

3) But, in fact, when I switch "V-sync" on, I can't see screen tearing. Why?

Thanks a lot for the answers.

**Tags:** rendering, gpu


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## 1 answers

### Answer by username_1 on 2016-04-05. Score: 3 | Accepted answer

V-sync means that the GPU won't switch buffer until the current frame is done showing.

When you tell to swap the buffer with V-Sync enabled the actual swap doesn't happen until V-Blank, a small window between frames where nothing is being sent to the screen.

The reason I think you cannot see the update tear is that it moves across the screen during the update. While a non v-sync tear stays in the same place on the screen for 16 milliseconds.

> **Comments:**
> **username_0**: Yes, I heard triple buffer technology. That's cool. Thanks.  

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