Backfaces not culled on HD family GPU machines

[idata]

Backward facing polygons are being selected/picked in an OpenGL program when the program is run on machines with Intel HD family GPUs.

Picking works as expected on other types of GPU.

glCullFace is enabled.

The code uses old OpenGL API and uses the Select buffer technique.

glGetIntegerv (GL_VIEWPORT, @vp);

glSelectBuffer (16*32, @selectBuf);

glMatrixMode(gl_projection);

glpushmatrix;

glRenderMode(GL_SELECT); //select

glloadidentity();

gluPickMatrix( mouse_x,vp[3]-mouse_y, 0.09,0.09, vp);

gluPerspective(45,control.width/control.height,0.1,100);

//---------------

redraw; //calls a compiled display list

//---------------

glMatrixMode(gl_projection);

glpopmatrix;

hits:= glRenderMode(GL_RENDER);

A video of the problem can be seen in this post http://www.tombraiderforums.com/showpost.php?p=7479833&postcount=265 http://www.tombraiderforums.com/showpost.php?p=7479833&postcount=265.

Testing confirms that the backfaces are being counted as a hit on HD GPU only.

Anyone know the reason for this behaviour with Intel HD graphics?

[idata]

After further testing I believe Intel OpenGL driver is broken and incorrectly returns culled faces as a hit in the selection mechanism.

This issue was reported before, /message/92228# 92228 https://communities.intel.com/message/92228# 92228

[Bryce__Intel · Accepted solution]

The issue is resolved in our latest drivers. I'm trying to get confirmation if it was in our latest that was already released to public or if it's in our next driver. Either way, expect the fix in 15.40. We're working on porting the fix back to 15.36 as well.

[Bryce__Intel]

We're tracking this in the below thread.