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By Design

Votes

0

Found in

2017.4.0f1

2017.4.29f1

2018.3.0a1

2018.4.0f1

2019.1.0a1

2019.2.0a1

2019.3.0a1

Issue ID

1160487

Regression

No

Two Cameras with identical Viewport Rects create Six Draw Calls instead of Two

Camera

-

To reproduce:

1. Download attached “case_675421-ViewportIssueExample.zip" project and open in Unity
2. Open "TestScene" scene
3. Enter to Play mode
4. Open Frame Debugger window and press Enable

Expected Result: There are only two Draw Calls, a "Clear" due to the Clear flag in BackgroundCamera, and a "TransparentGeometry" for the Particle System (rendered by ParticleCamera)
Actual Result: There are 6 Draw Calls

Notes:
- This issue appears on Standalone, iOS and Android platforms
- This only happens if the two PartialScreenCameras have exactly same Viewport Rects and are rendered in Sequence
- All cameras have MSAA flag enabled (note that MSAA is disabled from Quality Settings) and there is at least one Camera rendering on top of those two Cameras (ParticleCamera in the Test Scene)
- From Unity 2019.2 I get 7 Draw Calls and when I edit one of the PartialScreenCamera's viewport I get 3 Draw Calls
- Workaround: You can switch between 2 and 6 Draw Calls by changing one of the PartialScreenCamera's viewport

Reproduced on Unity 2017.4.0f1, 2017.4.28f1, 2018.3.14f1, 2018.4.2f1, 2019.1.6f1, 2019.2.0b5 and 2019.3.0a5

  1. Resolution Note (2019.3.X):

    by-design in current camera stacking system. If the camera that is doing the rendering has MSAA turned on, then the other cameras will also have MSAA so that's why draw calls increase from 2 to 6.

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