Materials with transparency not properly rendered in viewport in Material Render mode (cycles) #45789

New Issue

Dolphin Dream · 2015-08-13T17:48:19+02:00

Dolphin Dream commented

2015-08-13 17:48:19 +02:00

System Information
OS: Ubuntu 14.04 (64 bit)
RAM : 7.8 GiB
CPU: Intel® Core™ i5-2400 CPU @ 3.10GHz × 4
GFX: GeForce GT 520/PCIe/SSE2

Blender Version
2.75 (hash: 65c3207)

Short description of error
Using cycles engine.. materials with transparency are not properly rendered in viewport in Material Render mode. The objects having these transparent materials render correctly in Rendered mode.

Exact steps for others to reproduce the error
See the attached blend file and screenshots. Basically create a background object (sphere).. create a quad and place it in front of the background object. Add a material to the quad with a combination of emission and transparency shader modulated by some image (a black and white masking image). Enable Rendered mode in the viewport (this works fine, showing transparency) .. then enable the Material render mode (this does not render the transparent parts properly.. the transparent parts are opaque).

A solution I found for this (though this is a HACK in my opinion) is to switch to Game Engine, change the Alpha Blend mode from opaque to Alpha Blend, then switch back to Cycle engine. After this both the Material and the Rendered preview modes show the transparent parts properly in the viewport. I would think that the preview rendering should work as expected in the Material render mode without jumping through hoops.. or at least give the option to change the alpha blend modes directly in the UI available under cycles engine. In general having settings "hidden" under other engine modes (e.g. game engine) that affect the way things render under cycles engine is weird.. bad.. unacceptable.. (add your own adjective here) :)

The 3 screenshots show the viewport preview in Rendered mode.. in Material mode (before game engine/alpha blend switch) .. and in Material mode (after game engine/alpha blend switch).
materialRenderViewportBug.blend

**System Information** OS: Ubuntu 14.04 (64 bit) RAM : 7.8 GiB CPU: Intel® Core™ i5-2400 CPU @ 3.10GHz × 4 GFX: GeForce GT 520/PCIe/SSE2 **Blender Version** 2.75 (hash: 65c3207) **Short description of error** Using cycles engine.. materials with transparency are not properly rendered in viewport in Material Render mode. The objects having these transparent materials render correctly in Rendered mode. **Exact steps for others to reproduce the error** See the attached blend file and screenshots. Basically create a background object (sphere).. create a quad and place it in front of the background object. Add a material to the quad with a combination of emission and transparency shader modulated by some image (a black and white masking image). Enable Rendered mode in the viewport (this works fine, showing transparency) .. then enable the Material render mode (this does not render the transparent parts properly.. the transparent parts are opaque). A solution I found for this (though this is a HACK in my opinion) is to switch to Game Engine, change the Alpha Blend mode from opaque to Alpha Blend, then switch back to Cycle engine. After this both the Material and the Rendered preview modes show the transparent parts properly in the viewport. I would think that the preview rendering should work as expected in the Material render mode without jumping through hoops.. or at least give the option to change the alpha blend modes directly in the UI available under cycles engine. In general having settings "hidden" under other engine modes (e.g. game engine) that affect the way things render under cycles engine is weird.. bad.. unacceptable.. (add your own adjective here) :) The 3 screenshots show the viewport preview in Rendered mode.. in Material mode (before game engine/alpha blend switch) .. and in Material mode (after game engine/alpha blend switch). [materialRenderViewportBug.blend](https://archive.blender.org/developer/F223974/materialRenderViewportBug.blend) ![Screenshot from 2015-08-13 11:18:00.png](https://archive.blender.org/developer/F223977/Screenshot_from_2015-08-13_11_18_00.png) ![Screenshot from 2015-08-13 11:18:16.png](https://archive.blender.org/developer/F223976/Screenshot_from_2015-08-13_11_18_16.png) ![Screenshot from 2015-08-13 11:18:34.png](https://archive.blender.org/developer/F223975/Screenshot_from_2015-08-13_11_18_34.png)

Dolphin Dream commented

2015-08-13 17:48:19 +02:00

Changed status to: 'Open'