[osg-users] nVidia HW: Lens Matched Shading, Single Pass Stereo - exposed in OpenGL?

[Voerman, L.]

Hi Christian,
I have the Single Pass Stereo working with ARB_viewport_array and and a
shader (attached). The required support for GL_ARB_viewport_array is on the
osg-submissions list. I have not done any work on the culling yet, as the
eyes are sufficiently close together to get a decent impression of
performance. bringing in light render passes would probably require a smart
adaptation of the cull frustum.
The nvidia stereo_view_rendering seems to be to limiting for my purposes,
as I think it requires the display to be aligned with the eyes, and we are
working with head-tracked systems where the user is able to rotate their
head.


Regards, Laurens.

in the vertex shader do:
gl_Position = gl_ModelViewMatrix * gl_Vertex;
instead of
gl_Position   = gl_ModelViewProjectionMatrix * gl_Vertex;

For the rest of the shaders I rely on the osg shadergenerator with base
shaders from osg-data.

new osg::Shader(osg::Shader::GEOMETRY, "#version 450\n" "#extension
GL_ARB_gpu_shader5 : enable\n" "layout (triangles, invocations = 2) in;"
"layout (triangle_strip, max_vertices = 3) out;" "uniform mat4
transform_block[2];" "in vec4 vbasecolor[];" "in vec2 vtexcoord[];" "out
vec4 basecolor;" "out vec2 texcoord;" "out int gl_Layer;" "void main(void)
{" " for (int i = 0; i < gl_in.length(); i++)" " {" " basecolor =
vec4(1,1,1,1);" " texcoord = vtexcoord[i];" " gl_Position =
transform_block[gl_InvocationID] * gl_in[i].gl_Position;" "
gl_ViewportIndex = gl_InvocationID;" " EmitVertex();" " }" "
EndPrimitive();" "}" );


On Thu, Jun 9, 2016 at 1:24 PM, Sebastian Messerschmidt <
sebastian.messerschmidt at gmx.de> wrote:

>
> Hi Christian
>
>> Hi all,
>>
>> has anybody looked at these new features of nVidia hardware?
>>
>> Lens Matched Shading and Single Pass Stereo are using new hardware and
>> driver features that allow the GPU to perform single pass transform+shading
>> of up to 16 independent view matrices.
>>
> Isn't the change-set of single pass stereo (
> https://www.opengl.org/registry/specs/NV/stereo_view_rendering.txt)
> shader only?
> So basically we need the NV_viewport_array2 support on the osg-side to
> implement it.
> Btw.: How is the relationship between viewports and bound FBOs for
> instance? Suppose I need to render to different MRTs for each viewport? Can
> anyone point to a good example here?
>
>
>> This could accelerate OSG's stereo rendering, provided that the features
>> are exposed thorugh documented OpenGL extensions.
>>
>> Also rendering of cubemaps for reflections and shadows could be greatly
>> accelerated (six views in one pass).
>>
> That would require some deeper changes in the culling/camera-setup I
> suppose, as multiple frusta have to be taken into account per
> draw-invocation.
>
>>
>> Christian
>>
> Cheers
> Sebstian
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