textureProjOffset on HD4000

[RAren]

Hello everyone,

i've encountered an odd bug on my Intel HD4000.

Using textureProjOffset in a GLSL shader to sample the shadow texture on different locations leads to some very bad results both in performance AND image quality: rendering drops from 20ms/frame to 50-60 ms/frame and most of the time, shadows are projected just wrong or not projected at all.

I notice that this problem is not present on my other setup with HD4600, nor on my discrete card (nvidia GT750M SLI).

Drivers are updated, reference hardware is a last generation Mac Mini with Windows 7 x64.

[Allan_J_Intel1]

Thanks for joining the community.

At this stage, the support for your product is offered through your computer manufacturer. I recommend checking the link below for troubleshooting assistance on your Apple computer:

http://www.apple.com/support/mac/ http://www.apple.com/support/mac/

Allan.

[ROBERT_U_Intel]

@ hjeldin, What version of Intel HD Graphics driver are you using? Additionally, can you provide the shader sample that exposes the issue?

Robert

[RAren]

Drivers version: 10.18.10.3464

Driver date: 2/27/2014

A really basic shader to test can be found here: http://pastebin.com/ydvhGUiv 1) textureProjOffset used VERT: # version 330 # extension GL_ARB_separate_shade - Pastebin.com

[ROBERT_U_Intel]

@ hjeldin, Could you please verify the issue with the latest driver ?

64-bit: Driver Download http://downloadcenter.intel.com/Detail_Desc.aspx?agr=Y&DwnldID=23714 here

[RAren]

I updated the graphics drivers but the issue is still there.

Any luck in reproducing it?

Thanks

[ROBERT_U_Intel]

@ hjeldin, we are still investigating the issue and should have test results soon, I will report back once I have more information from out OpenGL team.

Robert

[RAren]

Hello,

any update regarding this issue?

Thanks,

Riccardo.

[Allan_J_Intel1]

Sorry for the delayed answer

Engineering would like to know if the texture filters that were used in the application because the artifacts are seen when GL_TEXTURE_MIN_FILTER and GL_TEXTURE_MAG_FILTER is set to GL_LINEAR, but everything works as expected with GL_NEAREST.

They want to be sure that the application uses GL_LINEAR filtering.

Thank you for your patience and understanding.

Allan.

[RAren]

Yes, I use GL_LINEAR as both MAG and MIN filter.

I'll test with GL_NEAREST tomorrow on the device and let you know the results.

In the meantime, thanks and no problem for the delay.

[ROBERT_U_Intel]

@ hjeldin, Did you have a chance to test with GL_Nearest?

Thanks

Robert

[RAren]

sorry for the delay.

Performances did increase, but image quality of the projected shadow in my other setup with NVIDIA GT750M are of course bad(since it's GL_NEAREST). I should fetch multiple samples from fragment neighbourhood and interpolate the resulting value.

Unfortunately it seems that sampler2DShadow still projects wrong on the mac mini.

If it helps i can attach screenshots taken from both my setups

[ROBERT_U_Intel]

@ hjeldin, Please post the screenshots.

Thanks

Robert

[RAren]

Hello Robert_U,

This is the version running on my laptop with NVIDIA GT750M

this one, instead, on the Mac Mini

I also noticed that during the first frame on the integrated card, shadows are somewhat rendered correctly even though they're not in the right position.

Unfortunately i'm not able to grab a screenshot in that exact moment, so (i can't believe i'm actually saying this) i took a photo of it:

Thanks,

Riccardo.

[RAren]

Hello,

I managed to find another pc with an Intel i7-3610 QM (graphics chipset HD 4000) and, while on the Mac Mini the program runs fine without shadows, on this model it crashes.

Shader compilation and program linking doesn't return any error, but as i replace everything written in the shader with a "outColor = vec4(1)" it stops crashing.

Any idea?

Thanks,

Riccardo.